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Service Manual - Kymco Spare Parts

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1. quo 7 CYLINDER HEAD COVER 7 4 CAMSHAFT CAMSHAFT HOLDER 7 4 VINE RHEA Da 7 9 7 0 7 CYLINDER HEAD VALVES KYMCO Mongoose KXR 90 Mongoose KXR 90 50 7 CYLINDER HEAD VALVES KYMCO Mongoose KXR 90 Mongoose KXR 90 50 SERVICE INFORMATION GENERAL INSTRUCTIONS e The cylinder head can be serviced with the engine installed in the frame e When assembling apply molybdenum disulfide grease or engine oil to the valve guide movable parts valve arm and camshaft sliding surfaces for initial lubrication e The camshaft is lubricated by engine oil through the cylinder head engine oil passages Clean and unclog the oil passages before assembling the cylinder head e After disassembly clean the removed parts and dry them with compressed air before inspection e After removal mark and arrange the removed parts in order When assembling install them in the reverse order of removal SPECIFICATIONS Cylinder head compression pressure 1612kg cm2 Po Cylinder head warpage s west ura Camshaft cam height 280 gt 25 8073 25 65 Valve rocker arm to shaft clearance 0 034 0 09 Valve stem to guide 0 010 0 037 006 J clearance EX 0 025 0 052 Oe E _ Valve spring tee ens 1 38 Valve spring IN 3 47 3 87kg at 26 0mm E 8 29 10 19kg at29 0mm
2. The inside of the flywheel is magnetic Make sure that there is no bolt or nut before installation Woodruff Key 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 Hold the flywheel with the universal holder and tighten the flywheel nut Torque 3 5 4 5kgf m Universal Holder E017 Install the cooling fan Torque 0 6 1 0kgf m Install the fan cover and tighten bolts 14 11 KYMCO 15 IGNITION SYSTEM Mongoose KXR 90 50 IGNITION SYSTEM 15 3 CDLIUNIT INSPECTION 15 5 IGN TION GO 15 7 PULSER 15 8 IGNITION TIMING INSPECTION 15 8 15 0 KYMCO 15 IGNITION SYSTEM Mongoose KXR 90 50 A C Generator Pulser Coil Spark Plug 15 1 KYMCO 15 IGNITION SYSTEM Mongoose KXR 90 50 IGNITION CIRCUIT Mongoose KXR 90 Ignition Switch Kill Switch Safety Ignition Coil Pulser CDI Unit Coil Spark Plug Generator IGNITION CIRCUIT Mongoose KXR 50 Ignition Switch Kill Switch Safety Ignition Coil KC Spark Generator 15 2 KYMCO 15 IGNITION SYSTEM Mongoose KXR 90 50 SERVICE INFORMATION GENERAL INSTRUCTIONS Check the ignition system according to the sequence specified in the Troubleshooting e The ignition system adopts
3. Air cooling 9 84 ond puidinbz eornoopq 3 e gJ d lt lt A 8 oa Frame type KYMCO Mongoose KXR 90 50 Type mm 14 Throttle type PISTON CDI 28 BTDC 4000rpm Non contact point type NGK C7HSA Spark plug gap 0 6 0 7mm attery 12V4AH lutch CVT l0jomque Spark plug Ulo s S uontus Helical gear Automatic centrifugal SIUISUEIT uononpowx 9 255 FR RR tire rolling circumference mm Tire pressure Front kg cm Rear 0 25 35 35 Turning angle Brake system Rear Disk brake type OO Front Rear Swing arm Steel tube frame Swing axle Suspension 1 GENERAL INFORMATION SPECIFICATIONS Mongoose KXR50 Wheel base mm 9 0 Fuel Used Ground clearance mm Starting system Bore x stroke mm 39X41 4 Compression pressure kg cm M Port Imm timing Exhaust opm Imm Close LE cold mm Exhaust Lubrication type Oil pump type Oil filter type KYMCO Mongoose KXR 90 50 Tye B Non contact point type UIe SAS IO aTndre on contact point type NGK BR8HAS Non Spark plug gap 0 6 0 7mm 12V4AH Ulo s S uoniusT puidinbz eornoopq I IEN UOIS STUISUBIT UIe SAS IJeAodU uononpowx FR RR tire rolling circumference mm 1247 1247 Tire pressure
4. HH G G GR GR GR TAIL STOP LIGHT 12V 5 21W OIL INDI m a ee M Sur DC E oe DL ae amu S ien coi mu 7 SPARK PLUG ISS AG vit Ed 9 m 5 z T 9E FRAME 590 10 20 STARTER MOTOR KILL SW STARTER SW EARTH 30W 5W DIMMER SW 5 G ivl EA G ul AUTO 0 E BIS G UNIT COLOR COMB GROUND MARKING ar mow veuon o COMB SW SW UNIT KILL STARTER SW KILL SW SAFETY 1 23 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 WIRING DIAGRAM KXR 50 ON ROAD omn em 10 due a0 1 Hitt pre E um i L 1 1 Eee E E m SI io pui Ph 7 HH 1 24 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 TROUBLESHOOTING ENGINE WILL NOT START OR IS HARD TO START Inspection Adjustment Probable Cause Empty fuel tank logged fuel line between fuel tank and carburetor logged float oil passage logged fuel tank cap breather hole logged fuel filter logged fuel valve passage Check if fuel reaches carburetor by loosening drain screw Fuel reaches Fuel does not carburetor reach carburetor Remove spark plug and install it into spark plug cap to test spark by gt Faulty spark
5. Measure the secondary coil resistances with and without the spark plug cap Resistances Mongoose KXR 90 with plug cap 8 39 20 without plug 3 14KQ 20 C Mongoose KXR 50 with plug cap 8 81K 20 C without plug 3 51 20 Correctly operate the tester following the manufacturer s instructions Note The readings in this table are taken with a YF 3501 Tester 15 7 KYMCO 15 IGNITION SYSTEM Mongoose KXR 90 50 PULSER COIL INSPECTION This test is performed with the stator installed in the engine Disconnect the A C generator connector Measure the pulser coil resistance between the blue yellow and green wire terminals Resistance Mongoose KXR 90 121 10 209 Mongoose KXR 50 80 160 20 C Note The readings in this table are taken with a YF 3501 Tester REMOVAL Refer to chapter 14 for the A C generator removal IGNITION TIMING INSPECTION The CDI unit is not adjustable If the ignition timing is incorrect inspect the CDI unit pulser coil and A C generator and replace any faulty parts Remove the fan cover Warm up the engine and check the ignition F Mark Advance Mark timing with a timing light When the engine is running at the ignition timing is correct if the mark aligns with the index mark within 227 Ignition Timing Mongoose KXR 90 BTDC28 4000rpm Mongoose KXR 50 BT
6. 7 2 7 CYLINDER HEAD VALVES C KYMCO Mongoose KXR 90 Mongoose KXR 90 50 TORQUE VALUES Cylinder head cover bolt 0 8 1 2kgf m Shaft hold nut 1 8 2 2kgf m Apply engine oil to threads Tappet adjusting nut 0 7 1 1kgf m SPECIAL TOOLS Valve spring compressor E040 Tappet adjuster E036 TROUBLESHOOTING The poor cylinder head operation can be diagnosed by a compression test or by tracing engine top end noises Poor performance at idle speed White smoke from exhaust muffler e Compression too low e Worn valve stem or valve guide Damaged valve stem seal Compression too low Incorrect valve clearance adjustment Abnormal noise e Burned or bend valves e ncorrect valve clearance adjustment e ncorrect valve timing e Sticking valve or broken valve spring Broken valve spring Damaged or worn camshaft Poor valve and seat contact e Worn cam chain guide e Leaking cylinder head gasket e Worn camshaft and rocker arm e Warped or cracked cylinder head Poorly installed spark plug Compression too high Excessive carbon build up in combustion chamber 7 3 7 CYLINDER HEAD VALVES C KYMCO Mongoose KXR 90 Mongoose KXR 90 50 CYLINDER HEAD COVER REMOVAL Remove fuel tank Refer to the chapter 5 Disconnect the oil recycle tube at the cylinder head cover Remove the four bolts at the cylinder head cover then remove the cylinder head cover INSTALLATION Install a new cylinder head cove
7. Remove the dust seal of each side Dust Seal Remove the front wheel hub bearings and distance collar Distance Collar Dust Seal Dust Seal Wheel Bearings 12 6 12 FRONT WHEEL FRONT BRAKE FRONT CO KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 ASSEMBLY Apply grease to a new dust seal lip and install the dust seal Pack all bearing cavities with grease Drive in the left bearing Install the distance collar Drive in the right bearing e Do not allow the bearings to tilt while driving them in Outer Driver Driver Handle e Drive in the bearing squarely with the sealed end facing out Oil seal and bearing install E014 INSTALLATION Reverse the FRONT WHEEL REMOVAL procedures Apply the grease onto the bearings and oil seal lips of the wheel hub Install wheel hub side collar washer and tight the nut wheel hub Torque 5 5 6 5kgf m Install cotter pins and nut cover Always use a new cotter pin Do loosen the axle nut after torque tightening If the axle nut groove is not aligned with the cotter pin hole align groove with the hole by tightening up on the axle nut Install the front wheel and tighten the nuts wheel Torque 4 0 5 0kgf m 12 7 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 Brake Cable FRONT BRAKE REMOVAL Remove the wheel hub See page 12 4 Pull brake sho
8. Turning ani Brake system Front Swing axle Rear Swing arm Steel tube frame SUMON uspension KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 SERVICE PRECAUTIONS B Make sure to install new gaskets O rings circlips cotter pins etc when reassembling B When tightening bolts or nuts begin with larger diameter to smaller ones at several times and tighten to the specified torque diagonally Use genuine parts and lubricants B When servicing the motorcycle be sure to use special tools for removal and installation B After disassembly clean removed parts Lubricate sliding surfaces with engine oil before reassembly 1 4 1 GENERAL INFORMATION B Apply or add designated greases and lubricants to the specified lubrication points B After reassembly check all parts for proper tightening and operation B When two persons work together pay attention to the mutual working safety E Disconnect the battery negative terminal before operation B When using a spanner or other tools make sure not to damage the motorcycle surface After operation check all connecting points fasteners and lines for proper connection and installation B When connecting the battery the positive terminal must be connected first After connection apply grease to the battery terminals B Terminal caps shall be installed securely 1 5 KYMCO
9. start e Faulty ignition unit or incorrect ignition timing Faulty change gear control unit Improperly tightened A C generator flywheel KYMCO Mongoose KXR 90 50 No high voltage e Faulty ignition switch e Faulty ignition unit Poorly connected or broken ignition unit ground wire eDead battery or faulty regulator rectifier e Faulty ignition coil connector e Faulty pulser coil 15 4 KYMCO 15 IGNITION SYSTEM Mongoose KXR 90 50 CDI Unit CDI UNIT INSPECTION Remove seat 2 3 Disconnect the CDI coupler and remove the CDI unit Measure the resistance between the terminals using the electric tester e Due to the semiconductor in circuit it is necessary to use a specified tester for accurate testing Use of an improper tester in an improper range may give false readings e Use a YF 3501 Electric Tester e In this table Needle swings then returns indicates that there is a charging current applied to a condenser The needle will then remain at unless the condenser is discharged Mongoose KXR 90 ROAD Unit MQ Black Black Blue creen Probe Yellow Yellow M pe Black Yellow Black Yellow Black Blue Yellow AT 49 53 asss Note The readings in this table are taken with a YF 3501 Tester Blue Yellow Green 15 5 15 IGNITION SYSTEM KXR 90 ON ROAD Unit MO Proben Black Black Blue Giedi Probe Yel
10. Take care not to damage or break the piston rings during removal Clean carbon deposits from the piston ring grooves Inspect the piston wall for wear scratches damage If any defects are found replace the piston with a new one Install the piston rings onto the piston and measure the piston ring to groove clearance Service Limits Top 0 09 replace if over 2nd 0 09mm replace if over Remove the piston rings and insert each piston ring into the cylinder bottom Use the piston head to push each piston ring into the cylinder Measure the piston ring end gap Service Limit Top 0 5mm replace if over 2nd 0 65mm replace if over Oil ring 0 9mm replace if over Measure the piston pin hole Service Limit 13 04mm replace if over 8 6 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 Measure the piston pin O D Service Limit 12 96mm replace if below 255099 Measure the piston Take measurement at 10mm from the bottom and 90 to the piston pin hole Service Limit 46 9mm replace if below Measure the piston to piston pin clearance Service Limit 0 02mm replace if over CYLINDER INSPECTION Inspect the cylinder bore for wear or damage Measure the cylinder I D at three levels of top middle and bottom at 90 to the piston pin in both X and Y directions Cylinder I D Service Limit 47 1mm replace if over Measure the cylinder to piston cle
11. Inspect the return spring for weakness or damage 5 Inspect the kick starter spindle bushings for wear or damage Plastic Bushing Spindle Bushing Friction Spring Inspect the starter driven gear for wear or damage Inspect the friction spring for wear or damage Starter Driven Gear Starter Driven Gear Shaft Forcing Part Inspect the kick starter spindle and starter driven gear forcing parts for wear or damage ASSEMBLY Install the kick starter spindle bushing and return spring onto the left crankcase cover Install the kick starter spindle Apply grease on to the bushing and spindle teeth 9 5 Kick Starter Spindle KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 _ Friction Spring Kick Starter Spindle Cover Install the starter driven gear and friction spring onto the left crankcase cover as the figure shown Install the kick starter spindle cover and tighten three bolts Apply grease on to the driven gear shaft Starter Driven Gear Bolts First install the washer and then install the Circlip circlip Install the kick lever LEFT CRANKCASE COVER INSTALLATION First install the dowel pins Install the gasket Install the left crankcase cover and tighten the eight left crankcase cover bolts diagonally Left Crankcase Cover 9 6 9 DRIVE AND DRIVEN PULLEYS DRIVE PULLEY REMOVAL Remove the left crankcase cover Refer to the LEFT CRANKCASE CO
12. Replace if cracks bends or damage Do not attempt to straighten a bent arm this may dangerously weaken the arm Inspect bushes Replace if wear or damage Bushes INSTALLATION Reverse the REMOVAL procedures Apply the grease onto the bushes Install the front arm onto the frame and tighten the bolts and nut Torque 4 0 5 0kgf m Apply the grease onto the bushes Install the steering knuckle into the front arm and tighten the bolt and nut Torque 4 0 5 0kgf m Install the cotter pin and band ends of cotter pin Always use anew Install the tie rod into the steering knuckle and tighten the nut Torque 2 0 3 0kgf m Install the cotter pin and band ends of cotter pin Always use anew 12 12 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 STEERING SYSTEM HANDLEBAR REMOVAL Remove the following parts Handlebar and Front fender Refer to the FRAME section in the CHAPTER 2 INSPECTION Inspect the handlebar Replace if cracks bends or damage INSTALLATION Install handlebar and handlebar holder then tighten the four bolts Torque 1 8 2 5kgf m e Align the mark on the handlebar with the lower handlebar holder surface e Be sure the upper handlebar holder mark face to front e Fist tighten the bolts on the front side of the handlebar holder and t
13. Check the cylinder head for warpage with a straight edge and feeler gauge Service Limit 0 10mm replace if over Cylinder head Gasket CYLINDER HEAD INSTALLATION Install the cylinder head on the cylinder properly Be careful not to damage the mating surfaces Install a new cylinder head gasket onto the cylinder 8 11 8 CYLINDER PISTON KYMCO Mongoose KXR 90 50 Cylinder Head Bolts Installation Install and tighten the cylinder head bolts diagonally in 2 or 3 times Torque 0 8 1 2kg m Install the spark plug Torque 1 1 1 7kg m Install the engine hood and fan cover Perform the following inspections after installation e Compression test e Abnormal engine noise Cylinder air leaks Spark Plug Cylinder Head Engine Hood b Spark Plug Fan Cover 8 12 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 Cylinder CYLINDER PISTON Mongoose KXR 50 CYLINDER REMOVAL Remove the cylinder head Remove the exhaust muffler See page 2 7 Remove the reed valve See page 5 16 Remove the cylinder Remove the cylinder gasket Do not pry between cylinder and crankcase or strike the fins Piston Piston Pin PISTON REMOVAL Remove the piston pin clip to remove the piston pin and piston Do not damage or scratch the piston Do not apply side force to the connect ing rod when removing the piston pin Place clean shop towels in the cr
14. DRIVE BELT BRAKE SHOES BRAKE PADS BRAKE FLUID 3 12 BRAKE LEVER FREE PLAY 3 13 STEERING SYSTEM INSPECTION 3 14 TOE IN ADJUSTMENT 3 15 WHEELS TIRES 3 16 DRIVE CHAIN SLACK ADJUSTMENT 3 17 CABLE INSPECTION AND LUBRICATION 3 19 FRONT SUSPENSION LUBRICATION 3 19 HEADLIGHT BEAM ADJUSTMENT ON ROAD ONLY 3 20 BRAKE PEDAL ADJUSTMENT 90 ON ROAD ONLY 3 20 BRAKE FULID KXR 90 ON ROAD ONLY 3 21 3 0 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 SERVICE INFORMATION GENERAL N WARNING eBefore running the engine make sure that the working area is well ventilated Never run the engine in a closed area The exhaust contains poisonous carbon monoxide gas which may cause death to people eGasoline is extremely flammable and is explosive under some conditions The working area must be well ventilated and do not smoke or allow flames or sparks near the working area or fuel storage area SPECIFICATIONS Mongoose KXR 90 ENGINE Throttle grip free play 1 4mm Spark plug gap 0 6 0 7mm Spark plug Standard C7HSA Valve clearance IN 0 1m EX 0 1m Idle speed 1700x100rpm Engine o
15. Mongoose KXR 90 50 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 W If the fuse is burned out find the cause repair it Replace it with a new one according to the specified capacity B After operation terminal caps shall be installed securely B When taking out the connector the lock on the connector shall be released before operation E Hold the connector body when X connecting or disconnecting it E Do not pull the connector wire BE N PER E Check if any connector terminal is bending protruding or loose X X KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 The connector shall be inserted completely mEB X W If the double connector has a lock Snapping lock it at the correct position B Check if there is any loose wire B Before connecting a terminal check for damaged terminal cover or loose negative terminal E Check the double connector cover for proper coverage and installation B Insert the terminal completely B Check the terminal cover for proper coverage E Do not make the terminal cover opening face up E Secure wire harnesses to the frame with their respective wire bands at the X X designated locations Tighten the bands so that only the insulated surfaces contact the wire harnesses 1 7 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 sure it is secure X Q QO _ B After clamping che
16. discoloration or grooves If any defects are found replace the rocker arm shaft with a new one then inspect lubrication system Rocker Arm Rocker Arm Shafts Rocker Arm Bore Inspect the rocker arm bore cam lobe contact surface and adjuster surface for wear pitting scratches blue discoloration If any defects are found replace the rocker arm shaft with a new one then inspect lubrication system Contact Surface Adjuster Surface Measure each rocker arm shaft O D Measure the of each valve rocker arm Measure arm to shaft clearance Replace as a set if out of specification Service limits 0 10mm 7 6 7 CYLINDER HEAD VALVES Mongoose KXR 90 Mongoose KXR 90 50 CAMSHAFT HOLDER ASSEMBLY Reverse the CAMSHAFT HOLDER DISASSEMBLY procedures Align the cross cutout on the exhaust valve rocker arm shaft with the bolt of the camshaft holder Camshaft Bearings CAMSHAFT INSPECTION Check each camshaft bearing for play or damage Replace the camshaft assembly with a new one if the bearings are noisy or have excessive play Inspect camshaft lobes for pitting scratches blue discoloration Measure the cam lobe height Service Limits IN 26 33mm replace if below EX 25 65mm replace if below If any defects are found replace the camshaft with a new one then inspect lubrication system 7 7 7 CYLINDER HEAD VALVES KYMCO Mongoose KXR 90 Mongoose K
17. gt 14 8 Remove the eight right crankcase cover bolts and the right crankcase cover Remove the two bolts and oil separator cover Oil Separator Covel Remove the oil pump driven gear nut Oil Pump Prvan Gear Remove the oil pump driven gear and drive chain Drive Chain Nut 4 5 KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 Remove the two oil pump mounting bolts and the oil pump DISASSEMBLY Oil Pump Body Remove the screw and disassemble the oil pump Screws Outer Rotor INSPECTION Measure the pump body to outer rotor clearance Service Limit 0 25mm Oil Pump Body 4 6 KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 Outer Rotor Measure the inner rotor to outer rotor 22 m Service Limit 0 2mm Measure the rotor end to pump body clearance Service Limit 0 12mm Inner Rotor Outer Rotor ASSEMBLY Install the outer rotor inner rotor and pump shaft into the pump body Insert the pump shaft by aligning the flat on the shaft with the flat in the inner rotor Install the dowel pin Install the pump cover by aligning the hole in the cover with the dowel pin Pump Cover 4 7 4 LUBRICATION SYSTEM KYMCO Mongoose KXR 90 50 Tighten the screw to secure the pump cover Make sure that the pump shaft rotates freely without binding INSTALLATION Reverse the PUMP REMOVAL proced
18. 11 3 CRANKCASE CRANKSHAFT Mongoose KXR 90 11 4 CRANKCASE CRANKSHAFT Mongoose KXR 50 11 7 11 0 KYMCO Mongoose KXR 90 50 11 CRANKCASE CRANKSHAFT Mongoose KXR 90 11 1 KYMCO 11 CRANKSCASE CRANKSHAFT Mongoose KXR 90 50 Mongoose KXR 50 11 2 11 CRANKCASE CRANKSHAFT SERVICE INFORMATION GENERAL INSTRUCTIONS KYMCO Mongoose KXR 90 50 e This section covers crankcase separation to service the crankshaft The engine must be removed for this operation e The following parts must be removed before separating the crankcase Cylinder head Chapter 7 Mongoose K XR 90 Cylinder piston Chapter 8 Drive and driven pulleys Chapter 9 A C generator c Chapter 14 Starter clutch Chapter 16 Oil pump gt Chapter 4 SPECIFICATIONS Mongoose KXR 90 item Standard mm Service Limit mm Connecting rod big end radial clearance 0 0 008 Connecting rod small end free play 0 05 0 4 Crankshaft Run out SPECIFICATIONS Mongoose KXR 50 mam oo tm Standard mm Service Limit mm Connecting rod big end radial clearance o oa Connecting rod big end side clearance Crankshaft Run out A B a 774 0 1 0 15 TORQUE VALUES Crankcase bolt 0 8 1 2kgf m Cam chain tensioner slipper bolt 0 8 1 2kgf m Mongoose KXR 90 SPECIAL TOOLS Mongoose KXR 50 Crankcase puller Universal beari
19. 4 5kgf m 9 8 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 Universal Holder Clutch Outer CLUTCH DRIVEN PULLEY XM REMOVAL Remove the left crankcase cover Refer to the LEFT CRANKCASE COVER REMOVAL section in the chapter 9 Remove the drive pulley Refer to the DRIVE PULLEY REMOVAL section in the chapter 9 Hold the clutch outer with the universal holder then remove the clutch outer nut and Nut clutch outer Universal Holder E017 Remove the clutch driven pulley and drive belt Drive Belt Clutch Driven Pulley DRIVE BELT INSPECTION Check the drive belt for cracks separation or abnormal or excessive wear Measure the drive belt width Service Limit Mongoose KXR 90 16 5mm Mongoose KXR 50 17 5mm Use specified genuine parts for replacement CLUTCH OUTER INSPECTION Inspect the clutch outer for wear or damage Measure the clutch outer Service Limit Mongoose KXR 90 112 5mm Mongoose KXR 50 107 5mm 9 9 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 CLUTCH DRIVEN PULLEY DISASSEMBLY Lock Nut Wrench 39mm Hold the clutch driven pulley assembly with the clutch spring compressor Be sure to use a clutch spring compressor to avoid spring damage Clutch Spring Compressor E034 Clutch Spring Compressor Set the clutch spring compressor in a vise and remove the clutch drive plate nut Loosen the clutch spring compres
20. At change 0 11 liter At disassembly 0 12 liter TORQUE VALUES Transmission case cover bolt 2 4 3 0kgf m TROUBLESHOOTING Engine starts but ATV won t move e Damaged transmission e Seized or burnt transmission Oil leaks e Oil too rich e Worn or damaged oil seal 10 2 10 FINAL REDUCTION KYMCO TRANSMISSION SYSTEM Mongoose KXR 90 50 Bolts TRANSMISSION CASE COVER REMOVAL Remove the drive sprocket 26 2 Remove the left crankcase cover 9 2 Remove the clutch driven pulley 29 10 Drain the transmission gear oil into a clean container Remove the transmission case cover attaching bolts Remove the transmission case cover Remove the gasket and dowel pins Transmission Case Cover Bearings Inspect the bearings for allow play in the transmission case cover or the bearings turn roughly If any defects are found replace the bearing with a new one Inspect the final shaft bearing oil seal for wear or damage Do not remove the transmission case cover except for necessary part A replacement When replacing the drive Transmission Cover Oil Seal shaft also replace the bearing and oil seal Final Gear Countershaft Remove the final gear and countershaft Inspect the bearings for allow play in the transmission case cover or the bearing turns roughly If any defects are found replace the bearing with a new one 10 3 10 FINAL REDUCTION KYMCO TRANSMISSION SYSTEM
21. COVER WW 1 6 REMOVAL procedures Handlebar Cover Seat Lock Lever SEAT REMOVAL To remove the seat pull upward the seat lock lever and pull up the seat at the rear To install the seat align the tabs on the seat with the grommets on the frame and press the seat down until it locks Make sure that the seat is securely fitted Seat HANDLEBAR REMOVAL Remove handlebar cover See page 2 3 Remove the rear brake master cylinder attaching bolts disk brake Disconnect the rear brake cable drum brake Disconnect the handlebar switch coupler and lead under front fender Y Handlebar Switch Coupler Lead 2 3 KYMCO 2 FRAME COVERS EXHAUST MUFFLER Mongoose KXR 90 50 Disconnect the front brake cables Disconnect the remote stop switch and front brake stop switch leads Remove the two screws and speed limiter cover Disconnect the throttle cable Remove the two bolts and handlebar cover holder Remove the four bolts and upper handlebar holders Remove the handlebar INSTALLATION Reverse the HANDLEBAR REMOVAL procedures See page 12 13 Refer to the BRAKE LEVER FREE PLAY section in the chapter 3 to adjust brake lever free play Front Brake Cables e S Front Brake Stop Switch Leads Remote Engine Stop Switch Leads Throttle Cable 2 4 KYMCO 2 FRAME COVERS EXHAUST MUFFLER Mongoose KXR 90 50 FRONT
22. KXR 50 4 11 OIL FILTER CLEANING Mongoose KXR 50 4 12 4 0 KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 LUBRICATION SYSTEM Mongoose KXR 90 Rocker Arm Shaft Crankshaft Oil Filter Screen Oil Pump KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 LUBRICATION SYSTEM Mongoose KXR 50 4 2 KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 SERVICE INFORMATION Mongoose KXR 90 GENERAL INSTRUCTIONS The maintenance of lubrication system can be performed with the engine installed in the frame e Use care when removing and installing the oil pump not to allow dust and foreign matters to enter the engine and oil line Do not attempt to disassemble the oil pump The oil pump must be replaced as a set when it reaches its service limit e After the oil pump is installed check each part for oil leaks SPECIFICATIONS Item Standard mm Service Limit mm Oil pump Outer rotor to pump body clearance 0 15 0 20 Rotor end to pump body clearance 0 04 0 09 TROUBLESHOOTING Oil level too low Poor lubrication pressure e Natural oil consumption e Oil level too low Oil leaks Clogged oil filter or oil passages Worn or poorly installed piston rings e Not use the specified oil e Worn valve guide or seal 4 3 KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 SERVICE INFORMATION Mongoose KXR 50 GENER
23. KXR 90 50 REAR WHEEL HUB REMOVAL Remove rear wheel nuts See page 13 4 Remove the wheel hub nut cover and cotter pin Loosen nut attaching the wheel hub Nut Cover Cotter Pin Remove rear wheel See page 13 4 Remove wheel hub nut washer and wheel hub Elevate the wheels by placing suitable stand under the rear of frame Support the machine securely so there is no danger of it falling over Wheel Hub Splines INSPECTION Replace it if the wheel hub is cracks or damage Replace it if splines of the wheel hub is wear or damage INSTALLATION Apply grease onto the splines of the wheel hub Install wheel hub washer and wheel hub nut Torque 6 0 8 0kgf m Install the cotter pin and band ends of cotter pin Do not loosen the axle nut after torque tightening If the axle nut groove is not aligned with the cotter pin hole align groove with the hole by tightening up on the axle nut Always use a new cotter pin 13 5 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 REAR AXLE REMOVAL Remove the rear wheel hub of the both rear wheels See page 13 5 Remove the collars on the rear axle right and left side Collars Relax the drive chain Refer to the DRIVE CHAIN SLACK ADJUSTMENT section in chapter 3 Remove driven sprocket Remove the rear axle from right side Rear Axle Remove the two bolts and c
24. KYMCO 3 IISPECTION ADJUSTMENT Mongoose KXR 90 50 BRAKEN LEVER FREE PLAY DRUM BRAKE The brake lever free play A should be adjusted to 10 20 mm 0 4 0 8 in at the tip of the brake lever FRONT BRAKE FREE PLAY ADJUSTMENT CEFN Loosen the upper lock nut and fully turn in the adjusting bolt mmt 5g Loosen the lower lock nut Turn the lower adjusting bolt until specified free play is obtained Tighten the lower lock nut Lock Nuts Adjusting Bolts While applying the front brake turn out the upper adjusting bolt until the upper and lower cable lengths A are equal The cable joint will become vertical Tighten the upper lock nut REAR BRAKE FREE PLAY ADJUSTMENT Turn the adjusting nut on the brake hub in direction A to decrease play and in direction B to increase play KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 Make sure the cut out on the adjusting nut Is seated on the brake arm pin after making final free play adjustment Arm Pin Adjusting Nut STEERING SYSTEM INSPECTION Place the machine on a level place Check the steering column bushings and bearings Move the handlebar up and down and or back and forth Replace the steering column bushings and or bearings if excessive play Check the tie rod ends Turn the handlebar to the left and or right until it stops completely then slightly move the handlebar from left to right Replace the t
25. L TURNR PILOT 3 120128 se TURNLPILOT 12 12W o FR POSITION B 12V 3W 5 ord k TT TI ERR Tec 5 HEAD LIGHT 12V 35W 35W R Fs s pCre R Y v LGseGRO L G B LCD METER DES 9 S S 5 LGSBGRO L Y Weg M gt 4 STARTER HORN SW WINKER SW Du MOTOR HORN STARTER SW DIMMER SW 12V 10W ENGINE STOP SW STOR SW RH FR WINKER DIMMER SW HORN SW START SW WINKER SW ENGINE STOP SW COMB sw Hoea ee ool is E Fee ES EE MM 12V BATTERY PULSER SW UNIT KILL SAFETY WINKER RELAY 1 28 294 A Y BY E AUTO CDI BIS UNIT BLACK IGN COIL SPARK PLUG BROWN GREEN GR GRAY ORANGE SB SKY BLUE z xzx i oomvw BLUE LG LIGHT GREEN WHITE P PINK YELLOW SB Kk RH RR WINKER 12V 10W o KF 1489 5 TAIL STOP LIGHT 12V 5718W G G RR WINKER 12V 10W WHELL RPM SENSOR 1 22 KYMCO Mongoose KXR 90 50 WIRING DIAGRAM Mongoose KXR 50 OFF ROAD 1 GENERAL INFORMATION FR RR STOPSW STOPSW 12V 4AH BATTERY OIL LEVEL B R 1 G RYWG B Ll FUSE 7A HH
26. allow any foreign matters entering the brake reservoir when filling the brake reservoir with brake fluid Brake fluid will damage painted coated surfaces and plastic parts When working with brake fluid use shop towels to cover and protect painted rubber and plastic parts Wipe off any splash of brake fluid with a clean towel Do not wipe the motorcycle with a towel contaminated by brake fluid e Make sure to use recommended brake fluid Use of other unspecified brake fluids may cause brake failure Inspect the brake operation before riding SPECIFICATIONS Standard mm x 1m run out Rear wheel TORQUE VALUES Rear wheel nut 4 0 5 0kgf m Rear shock absorber upper mount bolt 3 5 4 5kgf m Rear shock absorber lower mount bolt 3 5 4 5kgf m Rear swing arm axle 6 0 8 0kgf m Rear wheel hub nut 6 0 8 0kgf m Brake arm bolt 1 8 2 5kgf m Caliper holder bolt 2 9 3 5kgf m Brake fluid tube bolt 3 0 4 0kgf m Caliper bleed valve 0 4 0 7kgf m Master cylinder bolt 1 0 1 4kgf m 13 2 13 REAR WHEEL SWING ARM HYDRAULIC BRAKE TROUBLESHOOTING Rear wheel wobbling e Bent rim e Faulty tire e Axle not tightened properly Soft rear shock absorber e Weak shock absorber spring e Faulty damper Loose brake lever Disk Brake e Air in hydraulic brake system e Brake fluid level too low e Hydraulic brake system leakage Hard braking Disk Brake e Seized hydraulic brake system e Seized piston Brake noise Disk Brake
27. e Contaminated brake pad surface Excessive brake disk run out Incorrectly installed caliper Brake disk or wheel not aligned Poor brake performance Disk Brake e Air in brake system Deteriorated brake fluid Contaminated brake pads and brake disk Worn brake pads e Worn brake master cylinder piston oil seal e Clogged brake fluid line Deformed brake disk Unevenly worn brake caliper 13 3 KYMCO Mongoose KXR 90 50 Poor brake performance Drum Brake e Brake not adjusted properly Worn brake linings e Worn brake shoes at cam contacting area e Worn brake cam e Worn brake drum Tight brake lever Disk Brake eSeized piston eClogged hydraulic brake system eSmooth or worn brake pad Poor brake performance Disk Brake Contaminated brake pad surface 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 REAR WHEEL REAR WHEEL REMOVAL Place the machine on a level place Remove four nuts attaching the wheel Elevate the rear wheels by placing a suitable stand under the rear of frame Support the machine securely so there is no danger of it falling over Remove wheel INSPECTION Measure the wheel runout Service Limit Vertical 2 0 mm Lateral 2 0nm Replace wheel if out of specification INSTALLATION Install the rear wheel and tighten the nuts wheel Torque 4 0 5 0kgf m 13 4 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose
28. e Lack of lubrication 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 FRONT WHEEL REMOVAL Place the machine on a level place Remove four nuts attaching the wheel panel and front wheel Elevate the front wheels by placing a suitable stand under the frame Support the machine securely so there is no danger of it falling over Remove the nut cover pr Remove the cotter pin Remove nut attaching the wheel hub and washer Nut Cover Washer Hub Nut Remove the collar and wheel hub Collar Wheel Hub 12 4 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 INSPECTION Measure the wheel run out Replace wheel or check bearing play if out of specification Rim run out limits Vertical 2 0mm Lateral 2 0mm Inspect the front wheel hub Replace it if cracks or damage Inspect the front brake drum Measure the front brake drum I D Service limits 84mm Keep oil or grease off the brake drum Turn the inner race of each bearing with your finger to see if they turn smoothly and quietly Also check if the outer race fits tightly in the hub Replace the bearings if the races do not turn smoothly quietly or if they fit loosely in the hub 12 5 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 FRONT WHEEL HUB DISASSEMBLY Side Collar Remove the side collar
29. end gap piston rng Obi 02507 09 Piston 0 D measuring position 4mm from bottom of skin TROUBLESHOOTING When hard starting or poor performance at low speed occurs check the crankcase breather for white smoke If white smoke is found it means that the piston rings are worn stuck or broken Compression too low or uneven compression Excessive smoke from exhaust muffler e Worn stuck or broken piston rings e Worn or damaged piston rings e Worn or damaged cylinder and piston e Worn or damaged cylinder and piston Compression too high Abnormal noisy piston Excessive carbon build up in combustion e Worn cylinder piston and piston rings chamber or on piston head e Worn piston pin hole and piston pin 8 3 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 SERVICE INFORMATION Mongoose KXR 50 GENERAL INSTRUCTIONS e The cylinder head cylinder and piston can be serviced with the engine installed in the frame Before disassembly clean the engine to prevent dust from entering the engine Remove all gasket material from the mating surfaces Do not use a driver to pry between the cylinder and cylinder head cylinder and crankcase Do not damage the cylinder inside and the piston surface e After disassembly clean the removed parts before inspection When assembling apply the specified engine oil to movable parts SPECIFICATIONS Cylndrheadwapage oo VALUES Cylinder he
30. ignition unit change gear control and the ignition timing cannot be adjusted e the timing is incorrect inspect the ignition unit generator change gear control and replace any faulty parts Inspect the ignition unit with a ignition unit tester Loose connector and poor wire connection are the main causes of faulty ignition system Check each connector before operation Use of spark plug with improper heat range is the main cause of poor engine performance e The inspections in this section are focused on maximum voltage The inspection of ignition coil resistance is also described in this section Inspect the spark plug referring to chapter 3 SPECIFICATIONS Mongoose KXR 90 item park plug Standard type NGK C7HSA Spark plug gap 0 6 0 7mm Primary Ignition coil resistance 20 Secondary Pulser coil resistance 20 C SPECIFICATIONS Mongoose KXR 50 item park plug Standard type BR8HAS Spark plug gap 0 6 0 7mm Primary Ignition coil resistance 20 Secondary Pulser coil resistance 20 C 15 3 15 IGNITION SYSTEM TROUBLESHOOTING High voltage too low e Weak battery or low engine speed Loose ignition system connection e Faulty ignition unit e Faulty ignition coil e Faulty pulser coil Normal high voltage but no spark at plug e Faulty spark plug Electric leakage in ignition secondary circuit e Faulty ignition coil Good spark at plug but engine
31. new one Connect the auto bystarter yellow wire to the battery positive 4 terminal and green black wire to the battery negative terminal and wait 5 minutes Connect a hose to the fuel enriching circuit and blow the hose with mouth If air can be blown into the hose the auto bystarter is faulty and replace it with a new one 5 15 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 Intake Manifold REED VALVE Mongoose KXR 50 REMOVAL Remove the oil pimp control cable plate See page 4 11 Remove carburetor See page 5 11 Remove the three intake manifold bolts and gasket Remove the reed valve and gasket Reed Stopper Reeds Reed Stopper INSPECTION Check the reed valve for damaged or weak reeds Check the reed valve seat for cracks damage or clearance between the seat and reed Replace the valve if necessary Do not disassemble or bend the reed stopper To do so can cause loss of engine power and engine damage If any of the stopper reed or valve seat is faulty replace them as unit Reed Valve Seat INSTALLATION Install the reed valve in the reverse order of removal Install a new gasket with the gasket indentation aligned with the reed valve After installation check for intake air leaks 5 16 KYMCO 6 ENGINE REMOVAL Mongoose KXR 90 50 ENGINE REMOVAL 6 SERVICE INFORMATION 6 1 ENGI
32. oil recycle tube from cylinder head and frame Remove the bolt at the air cleaner left side Loosen the screw at the band and remove bolt at the air cleaner right side then remove air cleaner INSTALLATION Reverse the REMOVAL procedures 5 9 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 Air Inlet Hose AIR CLEANER Mongoose KXR 50 CLEANING Refer to AIR CLEANER section in the chapter 3 REMOVAL Remove front fender See page 2 5 Disconnect the air inlet hose from the frame Remove the bolt at the air cleaner left side Loosen the screw at the band and remove bolt at the air cleaner right side then remove air cleaner INSTALLATION Reverse the REMOVAL procedures 5 10 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 CARBURETOR REMOVAL Remove the fuel tank carburetor cap and air filter Refer to chapter 5 Loosen the drain plug to drain the gasoline from the float chamber Sparks away from work area Drain gasoline into a clean container Fuel Drain Plug Insulator Auto Bystarter Disconnect the fuel tube from carburetor and auto bystarter leads sa Remove the two bolts nuts attaching carburetor then remove carburetor and insulator Bolts Fuel Tube Insulator O ring INSTALLATION Reverse the REMOVAL procedures When installation do not allow foreign particles to enter the car
33. plug connecting it to engine Fouled spark plug ground Faulty ignition unit Spark jumps Weak or no spark Faulty pulser coil Broken or shorted ignition coil Broken or shorted exciter coil Faulty ignition switch Weak or dead battery cylinder compression aulty starter clutch Valve clearance too small Valve stuck open Worn cylinder piston and piston rings Leaking cylinder head gasket Start engine by follow ing normal starting gt Procedure Air leaking through intake pipe Engine does not Engine fires but Leaking intake manifold fire does not start Incorrect ignition timing Incorrectly adjusted air screw Remove spark plug and inspect again Flooded carburetor Dry spark plug Wet spark plug Clogged air cleaner Throttle valve excessively open 1 25 1 GENERAL INFORMATION ENGINE LACKS POWER nspection Adjustment Start engine and Engine speed increases i accelerate lightly for _ observation Engine speed does not increase sufficiently Cary using a timing light Incorrect timing gt Normal Abnormal compression compression Not clogged Clogged inspect Plug not fouled Plug fouled or discolored discolored Remove oil dipstick and check oil level and conditio emove cylinder head oi pipe bolt and inspect Correct and not Incorrect or contaminated contamina
34. the crankcase to keep the piston pin clip from falling into the crankcase CYLINDER INSTALLATION Install the dowel pins and a new cylinder gasket on the crankcase Coat the cylinder bore piston and piston rings with clean engine oil Carefully lower the cylinder over the piston by compressing the piston rings Apply proper clean engine oil around cylinder wall e Be careful not to damage or break the piston rings e Stagger the ring end gaps at 120 to the piston pin 8 9 Mark 8 CYLINDER PISTON KYMCO Mongoose KXR 90 50 CYLINDER HEAD Mongoose KXR 50 REMOVAL Remove the spark plug cap Remove the exhaust muffler c 2 7 Remove the three bolts attaching the fan cover to remove the fan cover Remove the bolt attaching the engine hood to remove the engine hood The installation sequence is the reverse of removal Remove the spark plug Remove the cylinder head bolts and the cylinder head Loosen the bolts diagonally in 2 or 3 times Remove the cylinder head gasket Spark Plug Cap Fan Cover Engine Hood Cylinder Head Cylinder head Bolts ch aa wr KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 Combustion Chamber COMBUSTION CHAMBER DECABONIZING Remove the carbon deposits from the combustion chamber Avoid damaging the combustion cham ber wall and cylinder mating surface Mating Surface CYLINDER HEAD INSPECTION
35. the crankshaft bearings and check for excessive play Measure the crankshaft bearing play Service Limit Axial 0 20mm replace if over Radial 0 05mm replace if over Radial 11 5 KYMCO 11 CRANKSCASE CRANKSHAFT Mongoose KXR 90 50 CRANKCASE BALANCER INSTALLATION Install the cam chain into the left crankcase Install the dowel pins and a new gasket onto the left crankcase Place the right crankcase over the crankshaft and onto the left crankcase Install the crankshaft into the left crankcase When installing the crankshaft be careful not to damage the oil seal Install the right crankcase Tighten the crankcase attaching bolt Torque 0 8 1 2kgf m 11 6 KYMCO 11 CRANKCASE CRANKSHAFT Mongoose KXR 90 50 CRANKCASE CRANKSHAFT Mongoose KXR 50 REMOVAL Remove the crankcase attaching bolts Attach the crankcase puller on the right crankcase and remove the right crankcase from the left crankcase Crankcase puller E026 CRANKSHAFT REMOVAL Attach the crankcase puller on the left crankcase and remove the crankshaft from the left crankcase When removing the crankshaft do it slowly and gently Crankcase puller E026 When separating the crankcase the oil seals must be removed Replace the oil seals with new ones 11 7 KYMCO 11 CRANKSCASE CRANKSHAFT Mongoose KXR 90 50 Remove the remaining bearing on the crankshaft side using the universal bearing puller U
36. the left side of the machine INSTALLATION Reverse the REMOVAL procedures TORQUE VALUES Front engine bracket bolt 4 0 5 0kgf m Rear engine bracket bolt 2 0 2 4kgf m 6 3 KYMCO 0 ENGINE REMOVAL Mongoose KXR 90 50 Generator Starter Motor Couplers Bolts ENGINE REMOVAL Mongoose KXR 50 Remove frame covers and exhaust pipe Refer to chapter 2 Remove oil tank Refer to chapter 4 Remove air cleaner and carburetor Refer to chapter 5 Drain transmission oil Refer to chapter 3 Disconnect the A C generator and starter motor couplers Spark Plug Cap Drive Sprocket Remove the spark plug cap Remove the two bolts on the drive sprocket Remove the drive sprocket and washer Bolt and Nut Bolt and Nut Remove the front two mounting bolts and 1 two nuts at the engine right left side Remove the four bolts and then remove the left and right engine brackets at the engine right left side Remove the rear two mounting bolts and two nuts 6 4 KYMCO 6 ENGINE REMOVAL INSTALLATION Mongoose KXR 90 50 Remove the engine assembly to the left side of the machine INSTALLATION Reverse the REMOVAL procedures TORQUE VALUES Front engine bracket bolt 4 0 5 0kgf m Rear engine bracket bolt 2 0 2 4kgf m 6 5 7 CYLINDER HEAD VALVES KYMCO Mongoose KXR 90 Mongoose KXR 90 50 CYLINDER HEAD VALVES Mongoose KXR 90 SERVICE INFORMATION
37. the machine on a level place Place a container under the engine Remove the oil filler bolt and drain plug to drain the oil Reinstall the drain plug and tighten to specification Torque 1 0 2 0kgf m Fill the engine with oil and install the oil filler bolt Torque 1 0 2 0kgf m Oil Capacity At disassembly 0 12L At change 0 111 sure no foreign material enters the crankcase Start the engine and warm up for a few minutes While warming up check for oil leakage If oil leakage is found stop the engine immediately and check for the cause 3 11 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 DRIVE BELT Drive Belt Remove the left crankcase cover Inspect the drive belt for cracks scaling chipping or excessive wear Measure the V belt width Service limit Mongoose KXR 90 16 5mm Mongoose KXR 50 16 5mm Replace the drive belt if out of specification BRAK SHOES The checking of brake shoes wear will A disassemble the brake If the lining i A Ay thickness below to the wear limit A 2 0mm 0 08in to replace the shoes as a set BRAKE PADS A wear indicator is provided on each brake The indicators allows checking of brake pads wear Check the position of the indicator If the indicator reaches the wear limit line to replace the pads Inspection Window BRAKE FLUID Check if the fluid level is below the lower level mark through the inspection window 3 12
38. turn signal case tab REAR TURN SIGNAL LIGHT ON ROAD ONLY Remove the screw and remove the turn signal light lens Pull the bulb socket outside from the signal light case and remove bulb Install the bulb aligning the bulb socket groove with the bulb tab Install the bulb in the reverse order of removal 17 3 Bulb Socket KYMCO 17 BULBS REMOVAL INSTRUMENT HORN Mongoose KXR 90 50 INSTRUMENT ON ROAD REMOVAL Remove the handlebar cover See page 2 3 Disconnect the meter connectors Remove the two screws and then remove the instrument Installation is in the reverse order of removal K Ao Ca Connectors Instrument HORN ON ROAD Horn Connectors REMOVAL Disconnect the horn wire connectors Remove the bolt and remove horn Installation is in the reverse order of removal 17 4
39. 2Q 30 7 50 Mongoose KXR 50 510 20 30W5 90 Fan Cover A C GENERATOR REMOVAL Remove the four bolts attaching the cooling fan cover Remove the fan cover 14 8 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 Cooling Fan Remove the cooling fan by removing the four cooling fan attaching bolts Hold the flywheel with an universal holder Remove the flywheel nut Universal Holder E017 Remove the A C generator flywheel using the flywheel puller Flywheel Puller E001 Remove the pulser coil bolts Remove the A C generator wire rubber sleeve and pulser coil from the right crankcase Remove the two bolts and A C generator stator 14 9 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 A C GNERATOR INSTALLATION Flywheel 3 5 4 5kgf m Cooling Fan Woodruff Key A C Generator Wire Rubber Stator Sleeve Reverse the A C GENERATOR REMOVE procedures Install the A C generator stator and pulser coil onto the right crankcase Install the A C generator wire rubber sleeve Tighten the stator and pulser coil bolts Torques Pulser Coil 0 45 0 6kgf m Stator 0 8 1 2kgf m Connect the A C generator wire connector Clean the taper hole in the flywheel off any burrs and dirt Install the woodruff key in the crankshaft keyway Install the flywheel onto the crankshaft with the flywheel hole aligned with the crankshaft woodruff key
40. AL INSTRUCTIONS Use care when removing and installing the oil pump not to allow dust and dirt to enter the engine and oil line e Do not attempt to disassemble the oil pump Bleed air from the oil pump if there is air between the oil pump and oil line e If the oil is disconnected refill the oil line with motor oil before connecting it SPECIFICATIONS e Recommended Motor Oil SAE20W20 2 stroke Motor Oil e Oil Capacity 1 0 liter Light comes on 0 25 TROUBLESHOOTING Excessive white smoke or carbon deposits on spark plug Oil pump not properly synchronized excessive oil Poor quality oil Engine overheating Oil pump not properly adjusted insufficient oiling Poor quality oil Seized piston e No oil in tank or clogged oil line Oil pump not properly adjusted insufficient oiling e Air in oil line e Faulty oil pump Oil not flowing out of tank to engine e Clogged oil tank cap breather hole Clogged oil filter 4 4 KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 ENGINE OIL OIL FILTER Mongoose KXR 90 OIL LEVEL AND OIL CHANGE Refer to the ENGINE OIL section in the chapter 3 to check the oil level and replacement and oil filter cleaning OIL PUMP Right Crankcase Cover REMOVAL Place a container under the engine Remove the drain plug to drain the oil 3 9 Remove the A C generator flywheel gt 14 8 Remove the A C generator stator and pulsar coil
41. DC15 1700rpm 15 8 KYMCO 16 STARTING SYSTEM Mongoose KXR 90 50 STARTING SYSTEM SERVICE INFORMA diese 16 2 STARTER MOTOR 16 3 STARTER HEDA Y 16 6 STARTER CLUTCH Mongoose KXR 90 16 7 STARTER PINION Mongoose KXR 50 16 9 16 0 KYMCO 16 STARTING SYSTEM Mongoose KXR 90 50 Ei EX EE 7 T KAS 92 Starter Motor STARTING CIRCUIT Starter Relay G Y Ignition Switch Fuse A Stoplight Battery 2 S s Stop Switches 16 1 KYMCO 16 STARTING SYSTEM Mongoose KXR 90 50 SERVICE INFORMATION GENERAL INSTRUCTIONS e The removal of starter motor can be accomplished with the engine installed TROUBLESHOOTING Starter motor won t turn Lack of power e Fuse burned out e Weak battery e Weak battery e Loose wire or connection e Faulty ignition switch e Foreign matter stuck in starter motor e Faulty starter clutch or gear e Faulty front or rear stop switch e Faulty starter relay Starter motor rotates but engine does e Poorly connected broken or shorted wire not start e Faulty starter motor e Faulty starter clutch e Faulty change gear control unit e Starter motor rotates reversely e Weak battery 16 2 KYMCO 16
42. FENDER REMOVAL Remove the seat See page 2 3 Remove the handlebar See page 2 3 Remove the six screws and nuts attaching the front fender and right left foot boards Screws Screws Remove the four screws and two nuts attaching the front fender and rear fender at the right left side Remove the two bolts attaching front fender at the right left side Remover the fuel filler cap Atfter remove Sure to tighten fuel filler Remove the front fender and disconnect the ignition switch coupler During removal do not pull joint claws forcedly to avoid damage 2 5 KYMCO 2 FRAME COVERS EXHAUST MUFFLER Mongoose KXR 90 50 INSTALLATION Reverse the FENDER REMOVAL procedures After remove be sure to tighten the fuel filler cap REAR FENDER REMOVAL Starter Relay Ignition Unit Remove the front fender See page 2 5 Remove the battery See page 14 4 Remove the starter relay and CDI unit Remove the ten screws attaching the rear fender and foot boards at the right left side Screws Remove the two screws attaching the rear fender at the rear Remove the three bolts attaching the rear fender at the center and then remove the rear fender 2 6 KYMCO 2 FRAME COVERS EXHAUST MUFFLER Mongoose KXR 90 50 Bolts FOOT BOARD REMOVAL Remove front fender See page 2 5 Remover rear fender See page 2 6 Remove the four bolts attaching th
43. IAL TOOLS Mongoose KXR 50 Remarks Ret Page Flywheel puller Oil seal and bearing install Universal holder Clutch spring compressor Bearing puller Crankshaft install Crankshaft amp crankcase install Crankcase puller Crankshaft Bearing puller Float level gauge 1 14 1 GENERAL INFORMATION LUBRICATION POINTS ENGINE KYMCO Mongoose KXR 90 50 Valve guide valve stem movable part eGenuine KYMCO Engine Oil SAE15W 40 Cam lobes eAPI SG Engine Oil Valve rocker arm friction surface Cam chain Cylinder lock bolt and nut Piston surroundings and piston ring grooves Piston pin surroundings Cylinder inside wall Connecting rod piston pin hole Connecting rod big end Crankshaft right side oil seal Crankshaft one way clutch movable part Oil pump drive chain Balance gear A C generator Starter one way clutch Bearing movable part O ring face Oil seal lip Transmission gear and movable parts Gear oil SAE90 1 15 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 FRAME The following is the lubrication points for the frame Use general purpose grease for parts not listed Apply clean engine oil or grease to cables and movable parts not specified This will avoid abnormal noise and rise the durability of the ATV E Throttle Cable Steering knuckle Front Swing Bush Front Swing Arm Steering Column Lower 1 16 KYMCO 1 GENERAL INFORMATION Mongoo
44. ISTON Mongoose KXR 90 50 PISTON RING INSPECTION Measure each piston ring end gap Service Limits Top Second 0 40mm replace if over Set each piston ring squarely into the cylinder using the piston and measure the end gap CONNECTING SMALL END INSPECTION Install the piston pin and bearing in the connecting rod small end and check for excessive play Measure the connecting road small end I D Service Limit 17 03mm replace if over PISTON CYLINDER INSTALLATION Piston First install the expander in the second ring groove Then install the top and second rings in their respective ring grooves Top Ring 1st Ring The piston rings should be pressed into the grooves with even force After installation check and make sure that each ring is flush with the piston at several Second Ring points around the ring A ring that will not compress means that the ring groove has carbon deposits in it and should be cleaned 8 16 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 Cylinder Gasket Mark Install a new cylinder gasket on the mating om d A surface between the cylinder and crankcase Position the piston mark on the intake valve side Make sure that the ring end gaps are aligned with the piston ring pins in the ring grooves Lubricate the cylinder inside and piston rings with engine oil and install the piston into the cylinder while compre
45. Mongoose KXR 90 50 Primary Drive Axle PRIMARY DRIVE AXLE REMOVAL Remove the clutch friven pulley Refer to chapter 9 Remove the primary drive axle Inspect the final gear teeth Blue discoloration pitting wear Replace Inspect the countershaft gear teeth Blue discoloration pitting wear Replace 10 4 10 FINAL REDUCTION KYMCO TRANSMISSION SYSTEM Mongoose KXR 90 50 Primary Drive Axle INSTALLATION Reverse the TRANSMISSION REVOVAL section procedures Install the primary drive axle into the left crankcase Install the final gear and final shaft into left Final Shaft crankcase Install the countershaft and washer into the left crankcase Install the resin washer onto countershaft Install the dowel pins and a new gasket onto the right crankcase Install the transmission case cover and tighten transmission case bolt Torque 2 4 3 0kgf m Dowel Pins 10 5 10 FINAL REDUCTION KYMCO TRANSMISSION SYSTEM Mongoose KXR 90 50 Fill the engine with oil and install the oil filler bolt Refer to the TRANSMISSION OIL REPLACEMENT section in the chapter 3 Specified Gear Oil KYMCO SIGMA GEAR OIL 90s Oil Capacity At disassembly 0 12 liter At change 0 1 1liter 10 6 KYMCO 11 CRANKSCASE CRANKSHAFT Mongoose KXR 90 50 CRANKCASE CRANKSHAFT SERVICE INFORMATION
46. ND OIL FILTER CLEANING A Place the machine on a level place B Warm up the engine for several minutes and stop it C Place a container under the engine D Remove the oil filler cap and oil filter cap to drain the oil Be sure no foreign material enters the crankcase When removing the drain plug the compression spring oil strainer and O ring will fall out Take care not to lose these parts Compression Spring O ring E Clean the oil strainer with solvent F Inspect the O ring and replace if damaged G Reinstall the O ring oil strainer compression spring and drain plug Tighten the drain plug to specification Torque 1 0 2 0kgf m Before reinstalling the drain plug be sure Oil Filter to install the O ring compression spring and oil strainer Oil Capacity At disassembly 0 8L At change 0 7L 3 10 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 Oil Filter Bolt Measurement Hole TRANSMISSION OIL TRANSMISSION OIL MEASUREMENT Place the machine on a level place Remove the oil filler bolt and check the oil level It should be up to the brim of the hole If the level 1s low add oil to raise it to the proper level Reinstall the oil filler bolt and tighten to specification Torque 1 0 2 0kgf m Drain Plug TRANSMISSION OIL REPLACEMENT Place
47. NE REMOVAL Mongoose KXR 90 6 2 ENGINE REMOVAL Mongoose KXR 50 6 4 KYMCO 6 ENGINE REMOVAL INSTALLATION Mongoose KXR 90 50 SERVICE INFORMATION GENERAL INSTRUCTIONS A floor jack or other adjustable support is required to support and maneuver the engine Be careful not to damage the machine body cables and wires during engine removal Use shop towels to protect the machine body during engine removal e Parts requiring engine removal for servicing Crankcase Crankshaft 6 1 KYMCO 0 ENGINE REMOVAL Mongoose KXR 90 50 Bolts ENGINE REMOVAL Mongoose KXR 90 Drain engine oil and transmission oil Refer to chapter 3 Remove frame covers and exhaust pipe Refer chapter 2 Remove air cleaner and carburetor Refer to chapter 5 Remove the two bolts on the drive sprocket Remove the drive sprocket and washer Remove the spark plug cap Disconnect the A C generator and starter motor couplers Bolt Nut Bolt and Nut Remove the front two mounting bolts and two nuts at the engine right left side Remove the four bolts and then remove the left and right engine brackets at the engine right left side Remove the rear two mounting bolts and two nuts Disconnect the inlet hose from the frame Bolts and Nuts KYMCO 6 ENGINE REMOVAL INSTALLATION Mongoose KXR 90 50 Remove the engine assembly to
48. NSPECTION DRONE OR ss 14 E A N 14 0 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 Regulator Rectifier A C Generator CHARGING CIRCUIT 10181594 Generator orAS JSTpeeH 14 1 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 SERVICE INFORMATIONN GENERAL INSTRUCTIONS The battery electrolyte sulfuric acid is poisonous and may seriously damage the skin and eyes Avoid contact with skin eyes or clothing In case of contact flush with water and get prompt medical attention e The battery be charged and discharged repeatedly If a discharged battery is not used for a long time its service life will be shortened Generally the capacity of a battery will decrease after it is used for 2 3 years A capacity decreased battery will resume its voltage after it is recharged but its voltage decreases suddenly and then increases when a load is added e When a battery is overcharged some symptoms can be found If there is a short circuit inside the battery no voltage is produced on the battery terminals If the rectifier won t operate the voltage will become too high and shorten the battery service life e f a battery is not used for a long time it will discharge by itself and
49. PREFACE This Service Manual describes the technical features and servicing procedures for the KYMCO Mongoose KXR 90 50 Section 1 contains the precautions for all operations stated in this manual Read them carefully before starting any operation Section 2 is the removal installation procedures for the frame covers which subject to higher removal installation frequency during maintenance and servicing operations Section 3 describes the inspection adjustment procedures safety rules and service information for each part starting from periodic maintenance Sections 4 through 17 give instructions for disassembly assembly and inspection of engine chassis frame and electrical equipment Most sections start with an assembly or system illustration and troubleshooting for the section The subsequent pages give detailed procedures for the section The information and contents included in this manual may be different from the motorcycle in case specifications are changed KWANG YANG MOTOR CO LTD OVERSEAS SALES DEPARTMENT OVERSEAS SERVICE SECTION ANIONA Q T gt INSINdInOS TABLE OF CONTENTS GENERAL INFORMATION FRAME COVERS EXHAUST MUFFLER INSPECTION ADJUSTMENT LUBRICATION SYSTEM FUEL SYSTEM ENGINE REMOVAL CYLINDER HEAD V ALVES CYLINDER PISTON DRIVE AND DRIVEN PULLEYS FINAL REDUCTION TRANSMISSION KYMCO 1 GENERAL INFORMATION Mongoose K
50. STARTING SYSTEM Mongoose KXR 90 50 Starter Motor i STARTER MOTOR REMOVAL Before removing the starter motor turn the ignition switch OFF and remove the battery ground Then turn on the ignition switch and push the starter button to see if the starter motor operates properly Disconnect the starter motor cable Remove two mounting bolts at the starter motor attaching left crankcase then remove Front Cover the starter motor Mongoose KXR 90 s starter motor is located on the engine Mongoose KXR 50 s starter motor is located under the engine DISASSEMBLY Remove the two starter motor case screws front cover motor case and other parts Motor Case Case Screws Commutator INSPECTION Inspect the removed parts for wear damage or discoloration and replace if necessary Clean the commutator if there is metal powder between the segments Check for continuity between pairs of the commutator segments and there should be continuity Also make a continuity check between individual commutator segments and the armature shaft There should be no continuity 16 3 KYMCO 16 STARTING SYSTEM Mongoose KXR 90 50 STARTER MOTOR CASE CONTINUITY CHECK Check to confirm that there is no continuity between the starter motor wire terminal and the motor front cover Also check for the continuity between the wire terminal and each brush Replace if necessary Wire Terminal Measur
51. STEM Mongoose KXR 90 50 OIL TANK Mongoose KXR 50 OIL TANK REMOVAL Remove the oil level switch connector Remove the two bolts attaching the oil tank Oil Level Switch Connector Oil Inlet Tube Disconnect the oil inlet tube Drain the oil inside the oil tank into a clean container Remove the oil tank The installation sequence is the reverse of removal e Connect the oil tube properly Bleed air from the oil pump after installation See page 4 9 e The oil tube clip at the oil tank side must be locked from inside of the oil tube joint 4 10 KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 Oil Inlet Tube OIL PUMP Mongoose KXR 50 REMOVAL Do not allow foreign matters to enter the crankcase Before removing the oil pump clean the oil pump and crankcase surfaces Disconnect the oil outlet tube from the oil pump Disconnect the oil pump control cable from the pump body Disconnect the oil inlet tube Before disconnecting the oil line clip the oil line to avoid oil flowing out and then plug the oil line after it is disconnected Remove the oil pump control cable plate bolts Remove the oil pump from the crankcase Oil Pump Control Cable Plate OIL PUMP INSPECTION O ring Remove the oil pump and inspect the following items e Weakened O ring Damage to crankcase mating surface e Damage to pump body e Control lever operation e Oil leaks throug
52. SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 REAR WHEEL SWING ARM HYDRAULIC BRAKE SERVICE INFORMATION 13 2 REAR WHEEL 13 4 REAR SWING 13 10 HYDRAULIC BRAKE 13 15 BRAKE PAD DISK 13 16 BRAKE MASTER CYLINDER 13 17 BRAKE CALIPER 13 20 DRUM BRAKE 13 22 13 0 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 13 1 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 SERVICE INFORMATION GENERAL INSTRUCTIONS During servicing keep oil or grease off the brake drum and brake linings During servicing keep oil or grease off the brake disk and brake pads Drain the brake fluid from the hydraulic brake system before disassembly Contaminated brake disk or brake pads reduce stopping power Clean the contaminated brake disk with high performance brake degreaser and replace the brake pads e Do not use brake fluid for cleaning Bleed air from the brake system if the brake system is removed or the brake is soft Do not
53. VER REMOVAL section in the chapter 9 Hold the drive pulley using a universal holder and remove the drive face nut and washer Remove the drive pulley Universal Holder E017 Remove the movable drive face assembly and drive pulley collar DISASSEMBLY Remove the ramp plate Remove the six weight rollers 9 7 Starting Ratchet D Drive Pulley Nut KYMCO Mongoose KXR 90 50 Roller KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 INSPECTION Check each weight roller for wear or damage Measure each weight roller O D Service Limit 15 4mm replace if below Measure the movable drive face bushing Service Limit Mongoose KXR 90 24 06mm over Mongoose KXR 50 20 06mm over ASSEMBLY Install the weight rollers into the movable drive face Install the ramp plate Check the drive pulley collar for wear or damage Measure the O D of the drive pulley collar sliding surface Service Limit Mongoose KXR 90 23 94mm below Mongoose KXR 50 19 98mm below INSTALLATION Install the drive pulley face assembly and collar Install the drive pulley starting ratchet and nut When installing the drive pulley face compress it to let the drive belt move downward to the lowest position so that the drive pulley can be tightened Do not get oil or grease on the drive belt or pulley faces Torque Mongoose KXR 90 5 5 6 5kgf m Mongoose KXR 50 3 5
54. XR 90 50 GENERAL INFORMATION SERIAL NUMBER oo Led SPECIFICATIONS 1 2 SERVICE PRECAUTIONS st 1 4 TORQUE VALUES scie 1 12 SPECIAL TOOLS aiia 1 14 LUBRICATION POINTS 1 15 CABLE amp HARNESS ROUTING 1 18 WIRING DIAGRAM 1 21 PROUBLESHIOO TIN 1 25 1 0 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 SERIAL NUMBER LPS Location of Engine Serial Number Location of Engine Serial Number 1 1 1 GENERAL INFORMATION SPECIFICATIONS Mongoose KXR 90 Overall length mm 1430 910 Wheel base mm Engine type Fuel Used 92 nonleaded gasoline 18 7 8 18 9 8 104 Breaking distance m ANSI 20 6 below Starting system Motor amp Kick starter Gasoline 4 stroke Single cylinder Semi sphere O H C chain drive 47 51 8 Compression ratio 10 0 1 Compression pressure 16 0 kg cm 6 3 6500 0 7 5500 1mm 26 timing Exhaust 44 Imm 17 Valve 1 cold Idle speed rpm 0 1 0 1 1700rpm Forced pressure amp Wet sump nner outer rotor type Full flow filtration 0 8 liter Lubrication type Oil pump type Oil filter type Oil capacity Tp eT M PNE E 0 7 liter capacity Cooling Type UI9 SAS
55. XR 90 50 INSTALLATION Reverse CAMSHAFT REMOVAL procedures Note the following points 1 Turn the flywheel so that the mark on the flywheel aligns with the index mark on the crankcase Keep the round hole on the camshaft gear facing up and align the punch marks on the camshaft gear with the cylinder head surface Position the intake and exhaust cam lobes down and install the camshaft onto the cylinder head Refer to the VALVE CLEARANCE section in the chapter 3 Install the camshaft dowel pins and holder e Apply engine oil to the threads of the cylinder head nuts e Diagonally tighten the cylinder head nuts in 2 3 times e Position the camshaft holder mark on the exhaust valve side Torque Cam shaft hold nut 1 8 2 2kgf m Apply engine oil to threads 2 Turn the cam chain tensioner screw counter clockwise to release it Apply engine oil to a new O ring and install it Tighten the cam chain tensioner cap bolt to install O ring into groove properly 3 Adjust the valve clearance Refer to the VALVE CLEARANCE section in the chapter 3 7 8 7 CYLINDER HEAD VALVES Mongoose KXR 90 Mongoose KXR 90 50 CYLINDER HEAD REMOVE Remove the camshaft Refer to the camshaft remove section in the chapter 7 Remove the carburetor Refer to the CARBURETOR REMOVE section in the chapter 5 Remove the exha
56. ad bolt 0 8 1 2kg m Spark plug 1 1 1 7kg m TROUBLESHOOTING Compression too low hard starting or poor performance at low speed Abnormal noisy piston e Leaking cylinder head gasket e Worn cylinder and piston e Loose spark plug e Worn piston pin or piston pin hole e Worn stuck or broken piston and piston rings e Worn connecting rod small end bearing e Worn or damaged cylinder and piston Compression too high overheating or knocking Abnormal noisy piston rings e Excessive carbon build up in cylinder head e Worn stuck or broken piston rings or on piston head e Worn or damaged cylinder 8 4 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 CYLINDER PISTON Mongoose KXR 90 REMOVAL Remove the cylinder head Refer to the chapter 7 Remove the two dowel pins and cylinder head gasket Remove cam chain guide and then remove cylinder Fin Cam Chain Guide Dowel Pins Remove the cylinder gasket and dowel pins Clean any gasket material from the cylinder surface Be careful not to drop foreign matters into the crankcase Gasket Remove the piston pin clip Place clean Shop towel in crankcase to keep the piston pin clip from falling into the crankcase Press the piston pin out of the piston and remove the piston Piston Pin 8 5 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 INSPECTION Inspect the piston piston pin and piston rings Remove the piston rings
57. aliper and then remove brake disk Brake Disk Caliper 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 Remove the four bolts and rear axle hub INSPECTION Replace it if the rear axle is scratched excessively or damage Replace if splines and threads of the rear axle is wear or damage Measure the rear axle run out Service limit less than 1 5mm Replace if it is out of specification Do not attempt to straighten a bent axle Replace it if the driven sprocket is cracks or damage Replace it if splines of the driven sprocket is wear or damage Splines 13 7 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 Brake Drum Cover Inspect the driven sprocket Replace sprocket if more than 1 4 teeth wear or bent teeth Replace it if the brake disk is cracks or damage Replace it if splines of the brake disk is wear or damage Splines Inspect rear axle hub Oil Seal Replace it if bearing allow play in the axle hub or the bearing turns roughly Replace it if oil seal is wear or damage Replace it if rear axle hub is cracks bend or damage Bearing and oil seal replacement steps Clean the outside of the rear axle Remove the oil seal by a flat head screw driver a Oil Seal Place a wood block against the outer Bearings pea edge to protect this edge Remove the bearing by a general bearing puller Insta
58. and thoroughly lubricate it with SAE 30 50 motor oil Do not use any other lubricants on the drive chain They may contain solvents that could damage the O rings 3 18 KYMCO 3 IISPECTION ADJUSTMENT Mongoose KXR 90 50 CABLE INSPECTION AND LUBRICATION Damaged cable sheath may cause corrosion and interfere with the cable movement An unsafe condition may result so replace such cable as soon as possible Inspect the cable sheath Replace if damage Check the cable operation Lubricate or replace if unsmooth operation Hold cable end high apply several drops of lubricant to cable LEVER LUBRICATION Lubricate the pivoting parts of each lever SUSPENSION LUBRICATION Inject grease into the nipples using a grease gun until slight over flow is observed from the thrust covers Wipe off the excess grease Rear Swing Arm Nipple Front Swing Arm Nipple 3 19 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 HEADLIGHT BEAM SCIO ADJUSTMENT ON ROAD ONLY Vertical adjustment Turn the ignition switch ON and start the engine Turn on the headlight switch Adjust the headlight aim by turning the headlight aim adjusting screw BRAKE PEDAL ADJUSTMENT KXR 90 ON ROAD ONLY The brake pedal free play should be adjusted to 5 10 mm 0 2 0 4 in at the brake pedal pivot If the free play is incorrect adjust as follows Adjust Keep front brake lever free play
59. ank case to keep the piston pin clip from falling into the crankcase Piston Pin Clip Spread each piston ring and remove by lifting it up at a point just opposite the gap Remove the expander 8 13 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 CYLINDER PISTON INSPECTION Check the cylinder and piston for wear or damage Clean carbon deposits from the exhaust port area Be careful not to damage the cylinder inside wall Measure the cylinder bore at three levels of A B and C in both X and Y directions Avoid the port area Take the maximum figure measured to determine the cylinder bore Service Limit 39 05mm replace if over Inspect the top of the cylinder for warpage Service Limit 0 10mm replace if over 8 14 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 A Mark The cylinder has an A mark or no mark on it When replacing the cylinder with a new one use a cylinder having the same mark as the old one Measure the piston O D at a point 3mm from the bottom of the piston skirt Service Limit 38 90mm replace if below Measure the piston to cylinder clearance Service Limit 0 10mm replace if over Measure the piston pin hole I D Service Limit 12 03mm replace if over Measure the piston pin O D Service Limit 11 98mm replace if below Measure the piston to piston pin clearance Service Limit 0 03mm replace if over 8 15 KYMCO 8 CYLINDER P
60. arance Service Limit 0 1mm repair or replace if over The true roundness is the difference between the values measured in X and Y directions The cylindricity difference between the values measured at the three levels is subject to the maximum value calculated Service Limits True Roundness 0 05mm repair or replace if over Cylindricity 0 05mm repair or replace if over 8 7 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 PISTON RING INSTALLATION Install the piston rings onto the piston Apply engine oil to each piston ring e Be careful not to damage or break the piston and piston rings e All rings should be installed with the markings facing up e After installing the rings they should rotate freely without sticking Second Side Rail Oil Ring Side Rail Measure the connecting rod small end I D Service Limit 13 06mm replace if over Measure the connecting rod to piston pin clearance Service Limit 0 06mm replace if over Inspect the exhaust side and intake side chain guides Wear Damage Replace Exhaust Side Guide 8 8 8 CYLINDER PISTON KYMCO Mongoose KXR 90 50 PISTON INSTALLATION Remove any gasket material from the crankcase surface Be careful not to drop foreign matters into the crankcase Install the piston piston pin and a new piston pin clip e Position the piston IN mark on the intake valve side e Place a clean shop towel in
61. aring and install snap ring Apply grease to a new dust seal lip and install the dust seal e Do not allow the bearings to tilt while driving them in e Drive in the bearing squarely with the sealed end facing out Oil seal and bearing install E014 Apply the grease onto the bearings and oil seal lips of the frame Install steering column and collar then tighten the nut Torque 6 0 8 0kgf m Install cotter pins and band ends of cotter Always use anew 12 15 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 Apply the grease onto the rubber collar and then install the rubber collar Install the steering bracket and tighten the two bolts Torque 1 8 2 5kgf m Install the tie rods and tighten the nuts Torque 2 0 3 0kgf m Install the cotter pin and band ends of cotter pin Always use a new cotter pin Apply the grease onto the end of the throttle cable and end of the brake cable 12 16 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 TIE ROD REMOVAL Remove the cotter pin and nut at the steering knuckle Remove the cotter pin and nut at the steering column Remove the tie road INSPECTION Inspect the tie rod Replace if bend or damage Check the te rod end movement Replace it if the tie rod end exists free play or turns roughly Check the tapered su
62. at 10 20 mm 0 4 0 8 in 2 Loosen the locknuts R L front lower brake cables 3 Turn the adjusting bolts until the front lower brake cables is tensed 4 Apply the front brake lever and check front brake cam lever to make sure that the brake does not drag after adjusting R L Front Lower Cable Cable Joint Case Cover Cable Joint 5 While remove the cable joint case cover and applying the brake pedal make sure the left and right front lower cable lengths A and B are equal The cable joint will become vertical 6 Tighten the locknuts R L front lower brake cables KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 Brake Pedal Cable gt 7 Loosen the locknut Brake pedal cable 8 Turn the adjusting bolt until the specified free play is obtained 9 Tighten the locknut Brake pedal cable BRAKE FLUID KXR 90 ON ROAD ONLY Check if the fluid level is below the lower level mark through the inspection window Upper level mark UPPER Lower level mark 3 21 KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 LUBRICATION SYSTEM SERVICE INFORMATION Mongoose KXR 90 4 3 SERVICE INFORMATION Mongoose KXR 50 4 4 ENGINE OIL OIL FILTER Mongoose KXR 90 4 5 OIL PUMP BLEEDING Mongoose KXR 50 4 9 OIL TANK Mongoose KXR 50 4 10 OIL PUMP Mongoose
63. attaching the tie rod and steering knuckle Remove nut cover at the front arm Remove the cotter pin and nut attaching the front arm and steering knuckle Remove steering knuckle Steering Knuckle Nut Cotter pin INSPECTION Inspect the shock absorber rod Replace the shock absorber assembly if bends or damage Inspect the shock absorber Replace the shock absorber assembly if oil leaks Inspect the spring of the shock absorber by move the spring up and down Replace the shock absorber assembly if fatigue Inspect the steering knuckle Replace if cracks pitting or damage 12 10 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 Check the front arm brackets of the frame If bent cracked or damaged repair or replace the frame Check the tightening torque of the front arms securing nuts Torque 4 0 5 0kgf m Check the dust seal If wear or damage replace the dust seal Dust Seal Check the front arm side play by moving it from side to side If side play noticeable replace the bushings Check the front arm vertical movement by moving it up and down If vertical movement is tight binding or rough then replace the bushings Remove the two bolts and nut attaching the front arm Remove the front arm Front Arm 12 11 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 Bushes Inspect the front arm
64. be installed properly 16 5 KYMCO 16 STARTING SYSTEM Mongoose KXR 90 50 STARTER RELAY Starter Relay INSPECTION Remove the seat Refer to the chapter 2 Turn the ignition switch ON and the starter relay is normal if you hear a click when the starter button is depressed If there is no click sound Inspect the starter relay voltage e Inspect the starter relay ground circuit Check for continuity between the starter relay yellow red and green red wire terminals STARTER RELAY VOLTAGE Starter Relay Mongoose KXR 90 INSPECTION Connect a 12V battery across the starter relay yellow red and green red wire terminals Connect an electric tester between the starter relay large terminals and check for continuity between the two terminals The relay is normal if there is continuity Replace the starter relay with a new one if there is no continuity Starter Relay Mongoose KXR 50 16 6 16 STARTING SYSTEM STARTER PINION Mongoose KXR 90 REMOVAL Remove the left crankcase cover and drive pulley face Refer to chapter 9 Remove the starter one way clutch drive nut Special Lock nut socket wrench E015 Remove starter one way clutch drive Special Start clutch puller E006 Remove the reduction gear case Remove the reduction gear INSTALLATION Install each washer to the top and bottom of the reduction gear Apply grease to the reduction gear shaft forci
65. buretor Check the carburetor insulator and O rings for wear or damage When installation be Sure insulator Insulator face intake manifold 5 11 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 Auto Bystarte DISASSEMBLY Remove auto bystarter cap Remove the two screws and then remove auto bystarter and plate Auto Bystarter Cap Screws Screws Remove the three float chamber screws and remove the float chamber Float Chamber Pull out the float pin then remove float and Bloat Nave float valve Float Pin Remove the main jet needle jet holder and OS needle jet Remove the slow jet Remove the air screw and throttle stop Screw Main Jet Needle Jet Throttle Stop Screw Holder Needle Jet 5 12 5 FUEL SYSTEM KYMCO Mongoose KXR 90 50 CAUTIONS Be careful not to damage the jets and jet holder when removing them e Before removal turn the throttle stop screw and air screw in and count the number of turns until they seat lightly and then make a note of this Do not force the screw against its seat to avoid seat damage e Be sure to install the O ring in the reverse order of removal ASSEMBLY Reverse the DISASSEMBLY procedures When installing the air screw return it to the original position as noted during removal Refer to the CARBURETOR IDLE SPEED section in chapters to perform the idle speed adjust
66. ck each wire to make Do not squeeze wires against the weld or its clamp Q X B After clamping check each harness to make sure that it is not interfering with any moving or sliding parts B When fixing the wire harnesses do not make it contact the parts which will o Contact generate high heat Bi Route wire harnesses to avoid sharp edges or corners Avoid the projected ends of bolts and screws B Route wire harnesses passing through the side of bolts and screws Avoid the projected ends of bolts and screws KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 Route harnesses so they are neither pulled tight nor have excessive slack E Protect wires and harnesses with electrical tape or tube if they contact a sharp edge or corner SN B When rubber protecting cover is used to X protect the wire harnesses it shall be installed securely Bi Do not break the sheath of wire E If a wire or harness is with a broken sheath repair by wrapping it with protective tape or replace it B When installing other parts do not press or squeeze the wires 1 9 1 GENERAL INFORMATION B After routing check that the wire harnesses are not twisted or kinked B Wire harnesses routed along with handlebar should not be pulled tight have excessive slack or interfere with adjacent or surrounding parts in all steering positions B When a testing device is us
67. crack bend or damage 1 Inspect the thrust cover chain guide collar f and bush Replace them if wear or damage 3 Thrust Covers Bushes Thrust Covers Inspect the drive chain stiffness Clean and lubricate or replace it if stiff CLEAN Place it in kerosene and brush off as much dirt as possible Then remove the chain from the kerosene and dry the chain 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 This machine has a drive chain with small rubber O rings between the chain plates Steam cleaning high pressure washes and certain solvent can damage these O rings Use only kerosene to clean the drive chain INSTALLATION Reverse the REMOVAL procedure Apply grease onto the collar bush pivot shaft and thrust cover Install the swing arm and tightening the nut Torque 6 0 8 0kgf m Install the shock absorber and tightening the bolts Torque 3 5 4 5kgf m 13 14 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 HYDRAULIC BRAKE BRAKE FLUID CHANGE Place the machine on a level place and set the handlebar upright Remove the two screws attaching the brake fluid reservoir cap Use Shop towels to cover plastic parts and coated surfaces to avoid damage caused by splash of brake fluid Connect a transparent hose to the brake caliper bleed valve and then loosen the bleed valve nut Use a syringe to draw the bra
68. d replace with a new one Install the bulb aligning the bulb socket groove with the bulb tab and set the lock clip Install the rubber boot Install the front fender in the reverse order of removal TAIL BRAKE LIGHT Remove the two screws and then remove lens Remove the bulb by turning it counterclockwise and replace the bulb with a new one Installation is in the reverse order of removal 17 1 1 KYMCO 7 BULBS REMOVAL INSTRUMENT HORN Mongoose KXR 90 50 INDICATOR LIGHTS Remove the handlebar cover see page 2 3 and raise it Remove the bulb sockets by pulling them out Pull the bulb out of the socket and replace it with a new one Installation is in the reverse order of removal POSITION LIGHT ON ROAD ONLY Pull the bulb socket out of the position light case Pull the bulb out of the socket and replace it with a new one Installation is in the reverse order of removal FRONT TURN SIGNAL LIGHT ON ROAD ONLY Remove the turn signal light lens by a flat screwdriver Pull the bulb socket out from the signal light case and remove bulb Install the bulb aligning the bulb socket groove with the bulb tab Bulb Socket 22 Bulb 1 KYMCO 7 BULBS REMOVAL INSTRUMENT HORN Moneoose KXR 90 50 Install the bulb socket aligning the bulb socket groove with the turn signal case tab Install the turn signal lens aligning the turn signal lens groove with the
69. dually increase the engine speed to measure the limit voltage and current Limit Voltage Current 13 5 15 5 0 5 5000 If the limit voltage is not within the specified range check the regulator rectifier 14 6 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 REGULATOR RECTIFIER MAIN HARNESS CIRCUIT Regulator Rectifier INSPECTION Remove the front covers 42 2 Remove the regulator rectifier 4P coupler and check for continuity between the wire harness terminals according to the following Item Wire Color Between battery red Battery has and engine ground voltage Between ground green and engine ground Continuity exists Between lighting wire yellow and engine ground Remove the A C generator resistor coupler and auto stator has bystarter coupler and resistance turn the lighting switch OFF for inspection Between charging coil generator white and engine stator has ground resistance REGULATOR RECTIFIER INSPECTION White Red If the main harness terminals are normal check the regulator rectifier coupler for loose connection and measure the resistances between the regulator rectifier terminals Do not touch the tester probes with your finger because human body has resistance Use the following specified testers for accurate testing Use of an improper Green Yellow tester in an improper range may gi
70. e right left foot board FRONT CARRIER REMOVAL Remove the four bolts attaching front carrier at the right left side EXHAUST MUFFLER REMOVAL Remove the two nuts attaching the exhaust pipe and cylinder head Remove the three bolts attaching the exhaust muffler then remove the exhaust muffler 2 7 KYMCO 2 FRAME COVERS EXHAUST MUFFLER Mongoose KXR 90 50 Inspect the gasket If the exhaust gas leaks the gasket should be replaced Install by reversing the removal sequence Torque Exhaust muffler lock bolt 3 2 3 8kgf m Exhaust muffler lock nut 1 8 2 2kgf m sure to install a new exhaust gasket Gasket TAILLIGHT BULB REMOVAL Remove the two screws and taillight lens Turn bulb and remove it 2 8 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 SERVICE INFORMATION 3 1 MAINTENANCE SCHEDULE 3 3 FUEL LINE THROTTLE OPERATION 3 4 AIR CLEANER 3 5 SPARK PLUG CYLINDER COMPRESSION 3 7 VALVE CLEARANCE Mongoose K XR 90 3 8 CARBURETOR IDLE SPEED 3 8 ENGINE OIL Mongoose KXR 90 3 9 TRANSMISSION OIL 3 11
71. e bore areas Inner Needle Bearing Pack all bearing cavities with proper grease Specified grease Heat resistance 2309 Press a new needle bearing into the driven face Oil Seal And Bearing Install E014 Outer Bearing Snap Ring 9 12 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 CLUTCH DISASSEMBLY Remove the circlips to disassemble the clutch i Keep grease off the clutch linings Clutch Lining CLUTCH DRIVEN PULLEY ASSEMBLY 9 13 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 Install the damper rubbers on the drive plate pins Install the clutch weights shoes and clutch springs Set the circlips in the groove Clean the driven pulley faces and remove any grease from them Install the oil seal onto the moveable driven face Apply grease onto the Oil seal and install them onto the moveable driven face Install the movable driven face onto the driven face Apply grease to the guide rollers and guide roller pins and then install them into the holes of the driven face Install the seal collar Remove any excessive grease sure to clean the driven face off grease Set the driven pulley assembly collar OFF Driven Pulley Spring N ROAD driven face spring and clutch assembly onto the clutch spring compressor Align the flat surface of the driven face with the flat on the clutch drive plate Compress the clutch spring compres
72. e front wheel Jack the machine front wheel off the ground and be careful to prevent the machine from falling down During servicing keep oil or grease off the brake drum and brake linings e Inspect the brake system before riding SPECIFICATIONS Front wheel rim run out oo cu p 90 Axial Front brake drum 85 85 5 8 85 4 2 0 VALUES Steering stem nut 6 0 8 0kgf m Swing arm nut 4 0 5 0kgf m Front wheel nut 4 0 5 0kgf m Front wheel hub nut 5 5 6 5kgf m Front shock absorber upper mount bolt 3 5 4 5kgf m Front shock absorber lower mount bolt 3 5 4 5kgf m 12 2 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM SPECIAL TOOLS Oil seal and bearing install E014 TROUBLESHOOTING Hard steering heavy eInsufficient tire pressure Steers to one side or does not track straight e Uneven front shock absorbers e Bent front arm Bent steering knuckle Poor brake performance Incorrectly adjusted brake e Worn brake linings e Contaminated brake lining surface e Worn brake shoes at cam contacting area e Worn brake drum e Poorly connected brake arm 12 3 Mongoose KXR 90 50 Front wheel wobbling e Bent rim e Excessive wheel bearing play e Bent spoke plate e Faulty tire Improperly tightened axle nut Soft front shock absorber e Weak shock springs Insufficient damper oil Front shock absorber noise e Slider bending e Loose arm fasteners
73. e harness Poorly connected coupler Check CDI unit with a CDI unit tester Check ignition coil with CDI unit tester Abnormal Faulty ignition coil 1 30 KYMCO 2 FRAME COVERS EXHAUST MUFFLER Mongoose KXR 90 50 SERVICE INFORMATIONS deret ceu 9 5 PRANE COVERS er 3 EXHAUST MUFFLER REMOVAL 2 TAIDDIGHT BUDB dence eL 2 8 2 0 KYMCO 2 FRAME COVERS EXHAUST MUFFLER Mongoose KXR 90 50 2 1 KYMCO 2 FRAME COVERS EXHAUST MUFFLER Mongoose KXR 90 50 SERVICE INFORMATION GENERAL INSTRUCTIONS e When removing frame covers use special care not to pull them by force because the cover joint claws may be damaged Make sure to route cables and harnesses according to the Cable amp Harness Routing TORQUE VALUES Exhaust muffler lock bolt 3 2 3 8kgf m Exhaust muffler lock nut 1 8 2 2kgf m TROUBLESHOOTING Noisy exhaust muffler e Damaged exhaust muffler e Exhaust muffler joint air leaks Lack of power e Caved exhaust muffler e Exhaust muffler air leaks Clogged exhaust muffler 2 2 KYMCO 2 FRAME COVERS EXHAUST MUFFLER Mongoose KXR 90 50 FRAME COVERS HANDLEBAR COVER REMOVAL Remove the two screws attaching the handlebar cover Disconnect the oil level indicator leads Mongoose KXR 50 Remove the handlebar cover INSTALLATION Reverse the HANDLEBAR
74. e plate out from steering knuckle Disconnect the front brake cable from brake cam lever and remove the brake shoe plate Brake Shoe Plate Brake Cam Lever INSPECTION A Measure the front brake lining thickness Service limit 2 0mm replace it below DISASSEMBLY Remove return ring Remove the brake shoes ASSEMBLY Reverse the DISASSEMBLY procedures Keep oil or grease off the brake linings Brake Shoes 12 8 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 Install the brake shoe plate Make sure that the boss on the knuckle correctly engages with the locating slot on the brake shoe plate Install front wheel See page 12 7 Adjust the front brake cable free play Refer to the BRAKE LEVER FREE Boss Locating Slot PLAY section in the CHAPTER 3 Brake cable free play 10 20mm 12 9 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 FRONT SUSPENSION Upper Bolt Shock Absorber REMOVAL Elevate the front wheels by placing a suitable stand under the frame Support the machine securely so there is no danger of it falling over Remove the front wheel wheel hub brake shoe plate Refer to chapter 12 Remove the upper and lower bolt then Lower Bolt remove the shock absorber Nut Cover Cotter pin Nut Tie rod Remove the cotter pin and nut
75. e the length of the brushes Service Limit 8 5mm replace if below Check for continuity between the brushes If there is continuity replace with new ones Bearing Check if the needle bearing in the front cover turns freely and has no excessive play Replace if necessary Check the dust seal for wear or damage Dust Seal 16 4 KYMCO 16 STARTING SYSTEM Mongoose KXR 90 50 Front Cover Commutator ASSEMBLY Apply grease to the dust seal in the front cover Install the brushes onto the brush holders Apply a thin coat of grease to the two ends of the armature shaft Insert the commutator into the front cover Be careful not to damage brush and armature shaft mating surfaces e When installing the commutator the armature shaft should not damage the dust seal lip O ring Install a new O ring to the front cover Install the starter motor case aligning the tab on the motor case with the groove on the front cover Tighten the starter motor case screws When assembling the front cover and motor case slightly press down the armature shaft to assemble them Motor Case STARTER MOTOR INSTALLATION Connect the starter motor cable connector Check the O ring for wear or damage and replace it if necessary Apply grease to the O ring and install the starter motor Tighten the two mounting bolts Torque 0 8 1 2kgf m The starter motor cable connector must
76. e with groove in the caliper and tighten the fluid tube bolt Torque 3 0 4 0kg m Add the recommended brake fluid into the brake reservoir and bleed air from the brake system Refer to 13 15 Install the brake caliper onto rear axle hub and tighten the bolts Torque 2 9 3 5kg m DRUM BRAKE Brake Drum REMOVAL Remove wheel hub and axle hub See page 13 5 Remove brake drum Remove brake shoes 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 INSPECTION Inspect the inner surface of the brake drum is scratches polish brake drum lightly and evenly with emery cloth Measure the inside diameter of the brake drum Service limit 131mm Replace it if it is out of specification Measure the front brake lining thickness A A Service limit 2 0mm replace it if below A 4 INSTALLATION Reverse the procedures 13 23 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 BATTER CHARGING SYSTEM A C GENERATOR SERVICE INFORMATION BATTERY REMOVAL CHARGING SYSTEM REGULATOR RECTIFIER A C GENERATOR CHARGING COIL A C GENERATOR LIGHTING COIL RESISTOR I
77. ed make sure to understand the operating methods thoroughly and operate according to the operating instructions E Be careful not to drop any parts B When rust is found on a terminal remove the rust with sand paper or equivalent before connecting KYMCO Mongoose KXR 90 50 O X the instrument the instrument s RU emove Rusf 1 10 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 B Symbols The following symbols represent the servicing methods and cautions included in this service manual t Apply engine oil to the specified points Use designated engine oil for Engine Oil lubrication Am Apply grease for lubrication Grease Transmission Gear Oil 90 Caution Gear Oil Use special tool Warning 1 11 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 TORQUE VALUES STANDARD TORQUE VALUES iem Torque kgfm ltem Torque kgf m 5mm bolt and nut 4mm screw 6mm bolt and nut 5mm screw Smm bolt and nut gt 6mm screw SH bolt 10mm bolt and nut 6mm flange bolt and nut 12mm bolt and nut 8mm flange bolt and nut 14mm bolt and nut i 10mm flange bolt and nut Torque specifications listed below are for important fasteners ENGINE Mongoose KXR 90 Stud bolt Oil filter screen cap L cover Cam shaft holder Tappet ADJ nut Pivot tensioner bolt Lifter tensioner bolt Lifter tensioner cap Mission case bolt Missio
78. er brake pad ASSEMBLY Assemble the brake pads in the reverse order of removal 1 Make sure the pad spring has fitted Brake Bad Pad Spring 13 16 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 BRAKE DISK Measure the brake disk thickness Service Limit 3 0mm Measure the brake disk run out Service Limit 0 3mm Fluid Tube Bolt BRAKE MASTER CYLINDER REMOVAL Drain the brake fluid from the hydraulic brake system Do not splash brake fluid onto any rubber plastic and coated parts When working with brake fluid use shop towels to cover these parts Remove the two master cylinder holder bolts and remove the master cylinder When removing the brake fluid tube bolt be sure to place towels under the tube and plug the tube end to avoid brake fluid leakage and contamination 13 17 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 DISASSEMBLY Remove the piston rubber cover and snap ring from the brake master cylinder Snap Ring Pliers Master Cylinder from the brake master cylinder Clean the inside of the master cylinder and Remove the washer main piston and spring brake reservoir with brake fluid Spring Main Piston Snap Ring I INSPECTION Check the cylinder inside wall and spring for scratch corrosion or other abnormal condition If any abnormal condition is found replace the inner parts or master cyl
79. es away from the work area e Wipe off any spilled gasoline Remove front fender See page 2 5 Screws Switch the fuel valve OFP Disconnect the fuel outlet tube from fuel valve Remove two screws attaching the fuel valve and holder Fuel Outlet Tube Fuel Valve Remove the two bolts and then remove the Fuel Tank fuel tank _ INSTALLATION Reverse the FUEL TANK REMOVAL procedures FUEL VALVE REMOVAL e Keep sparks and flames away from the work area Drain gasoline into a clean container Remove the screw and then remove control switch Disconnect all fuel tubes and then remove fuel valve Screw Fuel Tubes 5 4 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 DISASSEMBLY Screws Control Shaft Washer Remove the two screws on the retaining ring and then remove retaining ring Remove the washer and control shaft Retaining Ring Rubber Gasket Fuel Valve Body Remove the rubber gasket from the fuel valve body INSPECTION Inspect the fuel valve body for dirt and clog Clean if necessary Replace the rubber gasket with new ones if z s they are damaged or deteriorated Replace the O rings with new ones if they Control Shaft O ring are damaged or deteriorated Tab Tab ASSEMBLY Reverse the DISASSEMBLY procedures Install rubber gasket control shaft washer and retaining ring Aligning the tab on t
80. et Dowel Pins Reverse the CYLINDER HEAD REMOVAL procedures Torque Cylinder head bolt 0 8 1 2kgf m KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 CYLINDER PISTON SERVICE INFORMATION Mongoose KXR 90 8 3 SERVICE INFORMATION Mongoose KXR 50 8 4 CYLINDER PISTON Mongoose KXR 90 8 5 CYLINDER HEAD Mongoose KXR 50 8 10 CYLINDER PISTON Mongoose KXR 50 8 13 8 0 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 Mongoose KXR 90 8 1 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 Mongoose KXR 50 8 2 KYMCO 8 CYLINDER PISTON Mongoose KXR 90 50 SERVICE INFORMATION Mongoose KXR 90 GENERAL INSTRUCTIONS e The cylinder and piston can be serviced with the engine installed in the frame Before disassembly clean the engine to prevent dust from entering the engine Remove all gasket material from the mating surfaces Do not use a driver to pry between the cylinder and cylinder head cylinder and crankcase Do not damage the cylinder inside and the piston surface e After disassembly clean the removed parts before inspection When assembling apply the specified engine oil to movable parts SPECIFICATIONS 1 s cua Cim ee Ring to groove Top 005 005 ow Piston Ring
81. goes to the oil pump Check for oil leaks Filter Screen 4 12 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 FUEL SYSTEM SERVICE INFORMATION 5 2 EL i LI eS Ui 5 4 PUEL VALVE REMOVAL sse eerie eee 5 4 THROTTLE VALVE 5 7 5 9 CARBURETOR 5 11 REED VAVLE Mongoose KXR 50 5 16 5 0 KYMCO Mongoose KXR 90 50 5 FUEL SYSTEM 5 1 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 SERVICE INFORMATION GENERAL INSTRUCTIONS Gasoline is very dangerous When working with gasoline keep sparks and flames away from the working area Gasoline is extremely flammable and is explosive under certain conditions Be sure to work in a well ventilated area Do not bend or twist control cables Damaged control cables will not operate smoothly e When disassembling fuel system parts note the locations of O rings Replace them with new ones during reassembly Before float chamber disassembly loosen the drain screw to drain the residual gasoline into a clean container e After the carburetor is removed plug the intake manifold side with a clean shop towel to prevent foreign matters from entering When cleaning the carburetor air and fuel jets
82. h oil seals e Worn or damaged pump pinion Do not disassemble the oil pump which cannot be used after disassembly 4 11 Gear Control Lever KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 OIL PUMP INSTALLATION e Lubricate the O ring with grease or engine oil before installation e Make sure that the oil pump is inserted into the crankcase e Apply molybdenum disulfide or grease to the pump pinion Install the oil pump into the crankcase Install the oil pump control cable plate Connect the oil inlet line and oil outlet tube properly Connect the oil pump control cable Bleed air from the oil pump See page 4 9 Grease or Engine Oil Connect the oil tube properly Bleed air from the oil pump after installation e The oil tube clip at the oil tank side must be locked from inside of the oil tube joint OIL FILTER CLEANING Mongoose KXR 50 Disconnect the oil tube at the oil pump side and allow oil to drain into a clean container Remove the tube clip at the oil tank side and disconnect the oil tube Remove the oil filter Clean the oil filter screen with compressed air Install the oil filter in the reverse order of removal and fill the oil tank with specified oil up to the proper level Bleed air from the oil pump and oil lines Connect the oil tubes securely e Install the tube clip at the oil tank side and also install the clip to the lower oil tube that
83. he control shaft with the outlet duct in the fuel valve body e Aligning the tab on the retaining ring with the outlet duct in the fuel valve body Outlet Duct Outlet Duct 5 5 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 INSTALLATION Main Fuel Tube Reverse the FUEL VALVE REMOVEAL procedures Connect all fuel tube X Outlet Fuel Tube Reserve Fuel Tube 5 6 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 Carburetor Cap THROTTLE VALVE N DISASSEMBLY Remove the fuel tank Refer to FUEL TANK section in the chapter 5 Remove the carburetor cap Pull out the throttle valve Throttle Cable Compress the spring to disconnect the throttle cable by hand Remove the spring from the throttle valve 5 7 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 Needle Retainer Throttle Valve Pry off the needle retainer and remove the jet needle Check the throttle valve and jet needle for wear or damage ASSEMBLY Reverse the DISASSEMBLY procedures Jet Needle Groove Install the throttle valve into the carburetor body Align the groove in the throttle valve with the throttle stop screw on the carburetor body Throttle Stop Screw 5 8 KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 AIR CLEANER Mongoose KXR 90 CLEANING Refer to AIR CLEANER section in the chapter 3 REMOVAL Remove front fender See page 2 5 Disconnect the
84. hen tighten the bolts on the rear side Refer to the BRAKE FREE PLAY section in the CHAPTER 3 to adjust front brake Brake cable free play 10 20mm 12 13 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM STEERING COLUMN REMOVAL Remove handlebar Refer to FRAME COVER section in chapter 2 Remove the cotter pins and nuts attaching the tie rods then remove tie rods Remove the cotter pin and nut attaching the steering column then remove steering column and collar Remove the two bolts to remove the steering bracket and rubber collar Remove steering column and collar INSPECTION Inspect the steering column Replace it if bends or damage Do not attempt to straighten a bent shaft this may dangerously weaken the shaft Inspect the collar Replace it if wear or damage Inspect the duty seals snap ring and bearing Replace them if wear or damage Mongoose KXR 90 50 Nut Cotter Pin Cotter Pins Nut Steering Bracket Rubber Collar i E 1 Bolts Steering Bracket Steering Column Collar Bearing M 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 Remove the dust seal of each frame side Remove the snap ring Remove the bearing INSTALLATION Apply grease to a new dust seal lip and install the dust seal under frame Pack bearing cavities with grease Drive in the be
85. ie rod ends if tie rod end has any vertical play Raise the front end of the machine so that there is no weight on the front wheels Check ball joints and or wheel bearings Move the wheels lately back and froth Replace the front arms and or wheel bearings if excessive free play 3 14 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 TOE IN ADJUSTMENT A Place the machine on a level place Measure the toe in Adjust if out of specification Toe in measurement steps Mark both front tire tread centers Raise the front end of the machine so that there is no weight on the front tires Fix the handlebar straight ahead Measure the width A between the marks Rotate the front tires 180 degrees until the marks come exactly opposite Measure the width B between the marks Calculate the toe in using the formula given below Toe in B A Toe in 0 15mm If the toe in is incorrect adjust the toe in Adjust the toe in step Mark both tie rods ends This reference point will be needed during adjustment Loosen the lock nuts tie rod end of both tie rods The same number of turns should be given to both tie rods right and left until the specified toe in is obtained so that the lengths of the rods will be kept the same Torque 2 5 3 5kgf m Tie rod End Nuts Tie rod sure that both tie rod are turned the same amount If not the machine will drift tight
86. il capacity At disassembly 0 8 liter At change 0 7 liter Gear oil capacity At disassembly 120cc At change 110cc Cylinder compression 16kg cm2 lt Ignition timing BTDC 28 4000rpm CHASSIS Front brake free play 10 20mm Rear brake free play 10 20mm TIRE PRESSURE a i 2 Rear 0 22kgf cm TIRE SIZE Front 18 7 8 Rear 18 9 8 TORQUE VALUES Front wheel nut 4 0 5 0kgf m Rear wheel nut 4 0 5 0kgf m 3 1 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 SPECIFICATIONS Mongoose KXR 50 ENGINE Throttle grip free play 1 4mm Spark plug gap 0 6 0 7mm Spark plug Standard NGK BR8HAS Idle speed 2000x100rpm Gear oil capacity At disassembly 120cc At change 110cc Cylinder compression 12kg cm2 lt Ignition timing BTDC 15 1700rpm CHASSIS Front brake free play 10 20mm Rear brake free play 10 20mm TIRE PRESSURE ee 0 22 TIRE SIZE Front 16 8 7 Rear 16 8 7 TORQUE VALUES Front wheel nut 4 0 5 0kgf m Rear wheel nut 4 0 5 0kgf m 3 2 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 MAINTENANCE SCHEDULE This chapter includes all information necessary to perform recommended inspections and adjustments These preventive maintenance procedures if followed will ensure more reliable vehicle operation and a longer service life The need for costly overhaul work will be greatly reduced This information applies t
87. inder 13 18 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 ASSEMBLY Before assembly apply brake fluid to all removed parts e During assembly the main piston and spring must be installed as a unit without exchange e When assembling the piston soak the cups in brake fluid for a while e Install the cups with the cup lips facing the correct direction Install the main piston and snap ring Install the rubber cover Install the brake lever Install the brake fluid tube with the bolt and two sealing washers the brake reservoir with recommended brake fluid to the upper level Bleed air from the hydraulic brake system See page 13 15 Place the brake master cylinder on the handlebar and install the master cylinder holder with the UP mark facing up aligning the tab on the holder with the hole in the handlebar First tighten the upper bolt and then tighten the lower bolt Torque 1 0 1 4kg m UP Mark 13 19 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 BRAKE CALIPER DISASSEMBLY Remove the brake caliper brake pads and pad spring See page 13 16 Place a clean container under the brake caliper and disconnect the brake fluid tube from the brake caliper Be careful not to splash brake fluid on any coated surfaces DISASSEMBLY Remove the brake caliper holder from the b
88. ke fluid out through the hose Bleed Valve Brake Reservoir BRAKE FLUID REFILLING Connect a transparent hose and syringe to the brake caliper bleed valve and then loosen the bleed valve nut Fill the brake reservoir with brake fluid and use the syringe to draw brake fluid into it until there is no air bubbles in the hose Then tighten the bleed valve nut Torque 0 4 0 7kg m Bleed Valve When drawing brake fluid with the syringe the brake fluid level should be kept over 1 2 of the brake reservoir height Use only the recommended brake fluid Recommended Brake Fluid DOT 4 13 1 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 BRAKE SYSTEM BLEEDING Connect a transparent hose to the bleed valve and fully apply the brake lever after continuously pull it several times Then loosen the bleed valve nut to bleed air from the brake system Repeat these steps until the brake system is free of air When bleeding air from the brake system the brake fluid level should be kept over 1 2 of the brake reservoir height Brake Lever Bleed Valve BRAKE PAD DISK BRAKE PAD REPLACEMENT Remove the two bolts attaching the brake caliper holder The brake pads be replaced without removing the brake fluid tube Remove the brake caliper Push the brake caliper holder and then remove brake pad 7X9 Brake Bad Remove the oth
89. ll the new bearings and oil seal by reversing the previous steps Distance Collar Do not strike the center race or balls of the bearing Contact should be made only with the outer race 13 8 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 INSTALLATION Reverse the REMOVAL procedures Install the rear axle hub Apply grease onto the oil seal lips bearings and bushes At this time the rear axle hub should not be tightened completely Final tightening is done after the chain slack adiustment Install the rear axle Install brake disk driven sprocket and collars Install wheel hub see page 13 5 and rear wheel see page 13 4 Adjust drive chain slack Refer to the DRIVE CHAIN SLACK ADJUSTMENT section in chapter 3 Approximately 10 20 mm 13 9 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 REAR SWING ARM REMOVAL Place the machine on a level place Elevate the rear wheels by placing a suitable stand under the rear of frame Support the machine securely so there is no danger of it falling over Remove the rear wheels rear hubs rear axle and axle hub Refer to the REAR WHEEL section in chapter 13 Remove the lower bolt attaching the rear shock absorber Lower Bolt When removing the lower bolt hold the swing arm so that it does not drop downwards when the bolt is removed Remove the upper bol
90. low Yellow BeN e Black Yellow Blue Yellow Note The readings in this table are taken with a YF 3501 Tester Mongoose KXR 50 OFF ROAD Unit Rrobe Black Black Black Blue Yellow Red White Yellow Probe k Yellow ii P ET EZES Note The readings in this table taken with a YF 3501 Tester 2 w 5 Black Red Black White Blue Yellow Green KXR 50 ON ROAD Unit Noo Black Black Black Blue Green Yellow Red White Yellow Probe Blue Yellow pe fe fo Note The readings in this table are taken with a YF 3501 Tester ka KYMCO Mongoose KXR 90 50 Black Yellow Black Blue Yellow Green Black White Green Blue Yellow Black Yellow Black Red Black Yellow Black White Blue Yellow Black Red Green 15 6 KYMCO 15 IGNITION SYSTEM Mongoose KXR 90 50 IGNITION COIL REMOVAL Remove the spark plug cap Disconnect the ignition coil wires and remove the ignition coil bolt and ignition coil Coil INSPECTION CONTINUITY TEST The CDI unit is not adjustable If the timing 15 incorrect inspect the CDI unit pulser coil and A C generator and replace any faulty parts Measure the resistance between the ignition coil primary coil terminals Resistance Mongoose KXR 90 2 2 2 60 209 Mongoose KXR 50 3 7 15 20 20
91. lter oil to the 7 element If foam air filter oil 5 not available motor oil may be used The element should be wet but not dripping 5 Reinstall the element to the air filter case 6 Reinstall the element assembly and parts removed for access Apply the engine oil Squeeze out the excess oil CHANGE INTERVAL More frequent replacement is required when riding in unusually dusty or rainy areas 3 6 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 SPARK PLUG Remove the ignition coil cap and spark plug Check the spark plug for wear and fouling deposits Clean any fouling deposits with a spark plug cleaner or a wire brush Specified Spark Plug Mongoose KXR 90 NGK C7HSA Mongoose KXR 50 NGK BR8HAS Measure the spark plug gap Spark Plug Gap 0 6 0 7mm When installing first screw in the spark plug by hand and then tighten it with a spark plug wrench Washer Deformation Cracks Damage CYLINDER COMPRESSION Warm up the engine before compression test Remove the spark plug Insert a compression gauge Open the throttle valve fully and push the starter button to test the compression Compression Mongoose KXR 90 16kg cm Mongoose KXR 50 12kg cm If the compression is low check for the following Leaky valves Valve clearance too small Leaking cylinder head gasket Worn piston rings Worn piston cylinder Compression Gauge If the c
92. ment e After the carburetor is installed be sure to perform the Exhaust Emission 5 13 Spring Washer O ring Air Screw Throttle Stop Screw Spring Main Jet Needle Jet Needle Jet Holder Slow Jet KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 CARBURETOR CLEANING Blow compressed air through all passages of the carburetor body FLOAT FLOAT VALVE INSPECTION Inspect the float valve seat for wear or damage Inspect the float for damage or fuel level inside the float chamber O ring FUEL RESERVOIR O RING CHECK Remove the O ring Inspect the check the O ring for damage Replace with new ones if necessary FLOAT LEVEL INSPECTION Turn the carburetor upside down so that the float will go down to make the float valve contact the float valve seat Then slowly tilt the carburetor and measure the float level with the float level gauge while the float pin just contacts with float valve Float Level 8 0mm KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 AUTO BYSTARTER INSPECTION Measure the resistance between the auto bystarter wire terminals Resistance 50 10 minutes minimum after stopping the engine If the resistance exceeds 50 replace the auto bystarter with a new one After the engine stops for 30 minutes connect a hose to the fuel enriching circuit and blow the hose with mouth If air cannot be blown into the hose clogged the auto bystarter is faulty Replace it with a
93. mes and sparks away from a charging battery A e Turn power ON OFF at the charger not at the battery terminals to prevent sparks near the battery to avoid explosion e Charge the battery according to the Quick charging should only be done in an emergency e Measure the voltage 30 minutes after the battery is charged Charging current Standard 0 4A Quick 4 0 Charging time Standard 5 10 hours Quick 30 minutes After charging Open circuit voltage 12 8V min 14 5 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 CHARGING SYSTEM SHORT CIRCUIT TEST Disconnect the ground wire from the battery and connect an ammeter across the battery negative terminal and the ground wire Turn the ignition switch OFF and check for short circuit Connect the electric tester positive terminal to ground wire and the tester negative terminal to the battery negative terminal If any abnormality is found check the ignition switch and wire harness for short circuit CURRENT TEST This inspection must be performed with an electric tester when the battery is fully charged Warm up the engine for inspection Connect the electric tester across the battery terminals Disconnect the red wire from the fuse terminal and connect an ammeter between the red wire lead and the fuse terminal as shown Attach a tachometer to the engine Start the engine and gra
94. n fill bolt Driver face nut Clutch outer nut Drive plate nut Oneway clutch bolt Oneway clutch nut flywheel nut oo 000 tn O 3 co 5 Apply CN Apply thread lock N Oil pump screw Head CYL stud bolt IN pipe Head CYL stud bolt EX pipe A C G Startor Fan 8 4 2 1 2 1 7 1 1 1 1 28 3 1 1 1 1 1 2 2 3 4 1 12 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 ENGINE Mongoose KXR 50 Cylinder head bolt Clutch drive plate nut Drive face nut Clutch outer nut flywheel nut Mission fill bolt Drive plate nut Spark plug Steering stem nut Front Swing arm nut Front wheel nut Rear wheel nut Front wheel hub nut Rear wheel hub nut Front shock absorber upper mount bolt Front shock absorber lower mount bolt Rear shock absorber upper mount bolt Rear shock absorber lower mount bolt Rear swing arm axle hub bolt Rear axle hub nut Front engine bracket bolt Rear engine bracket bolt Exhaust muffler lock bolt frame Exhaust muffler lock nut engine Rod end nut 5 BO DO A e e e 4 1 13 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 SPECIAL TOOLS Mongoose KXR 90 SSR Clutch spring compressor Bearing puller Valve spring compressor Oil seal amp bearing installer Tappet adjuster Long socket wrench Start clutch puller SPEC
95. ng part Then install in the reverse order of removal STARTER ONE WAY CLUTCH DISASSEMBLY Remove the 32mm lock nut with special tool Take the starter one way clutch drive gear off Lock nut socket wrench E015 16 7 KYMCO Mongoose KXR 90 50 Reduction Gear Case v Starter One way Clutch Drive Nut Reduction Gear Starter Gear Shaft Washers Reduction Gear Case Starter Oneway Clutch Drive Gear 32mm Lock Nut KYMCO 16 STARTING SYSTEM Mongoose KXR 90 50 INSPECTION Inspect the starter one way clutch drive gear teeth for burrs chips roughness wear Inspect the starter one way clutch drive gear contacting surfaces for pitting wear damage Teeth Contacting Surfaces Push the weight roller to arrow direction for unsmooth operation Replace starter clutch assembly gt Starter Oneway Clutch 32mm Lock Nut ASSEMBLY Install the starter one way clutch driver gear in the reverse order of removal Do not reuse the starter clutch bolts that have been removed Torque 5 0 6 0kgf m Starter Clutch Bolts Starter Oneway Clutch Drive Gear Check starter clutch operation Clutch operation checking steps nstall the starter wheel gear to the starter clutch and hold the starter clutch When turning the wheel gear clockwise 1 the starter clutch and the wheel gear sh
96. ng puller Crankshaft install tool Crankcase assembly tool Oil seal and bearing install tool TROUBLESHOOTING Abnormal engine noise Excessive crank journal bearing play e Excessive crankpin bearing play Excessive transmission bearing play 11 3 E026 E030 E016 E024 E014 KYMCO 11 CRANKSCASE CRANKSHAFT Mongoose KXR 90 50 CRANKCASE CRANKSHAFT Mongoose KXR 90 REMOVAL Remove the crankcase attaching bolt Separate the left and right crankcase halves e Do not damage the crankcase gasket surface e Never use a driver to pry the crankcase mating surfaces apart Remove the crankshaft from the left Crankshaft crankcase j Remove the cam chain Remove the gasket and dowel pins 22 Chain Clean off all gasket material from the crankcase mating surfaces Avoid damaging the crankcase mating surfaces KYMCO 11 CRANKCASE CRANKSHAFT Mongoose KXR 90 50 CRANKSHAFT INSPECTION Measure the connecting rod small end Service Limit 13 06 mm replace if over Measure the connecting rod small end free play A Out of specification 0 05 0 4 mm Replace the crankshaft Measure the crankshaft run out B Service Limit 0 10mm replace if over Measure the connecting rod big end side clearance C Service Limit 0 05mm replace if over Measure the crank width D Out of specification 45 15 45 2 mm Replace the crankshaft Turn
97. niversal bearing puller E030 Universal Bearing Puller CRANKSHAFT INSPECTION Measure the connecting rod big end side clearance Service Limit 0 6mm replace if over Measure the connecting rod big end radial clearance at two points in the X and Y directions Service Limit 0 04mm replace if over 11 8 KYMCO 11 CRANKCASE CRANKSHAFT Mongoose KXR 90 50 Measure the crankshaft runout Service Limit c n sm 0 100mm 0 150mm replace if over replace if over Check the crankshaft bearings for excessive play The bearings must be replaced if they are noisy or have excessive play CRANKSHAFT INSTALLATION Wash the crankshaft in cleaning solvent and then check for cracks or other faults e After check apply clean engine oil to all moving and sliding parts e Remove all gasket material from the crankcase mating surfaces Dress any roughness or irregularities with an oil stone 11 9 KYMCO 11 CRANKSCASE CRANKSHAFT Mongoose KXR 90 50 Drive a new crankshaft bearing into the right crankcase Oil seal and bearing install E014 Drive a new crankshaft bearing into the left crankcase Oil seal and bearing install E014 Install the crankshaft into the left crankcase Apply KYMCO ULTRA motor oil or molybdenum disulfide to the crank shaft bearings and connecting rod big end Apply grease to the lip of the oil seal and then install it Crankshaft install to
98. ny parts which show signs of deterioration damage or leakage Do not smoke or allow flames or sparks in your working area THROTTLE OPERATION Check the throttle to swing for smooth movement Measure the throttle to swing free play Free Play 1 4mm To adjust throttle free play 1 Slide the rubber sleeves back to expose the throttle cable adjuster 2 Loosen the lock nut then turn the adjuster to obtain the correct free play 1 4 mm or 0 04 0 16 in 3 Tighten the lock nut and reinstall the sleeve OIL PUMP ADJUSTMENT Mongoose KXR 50 Adjust oil pump control cable after the throttle grip free play is adjusted Open the throttle valve fully and check that the index mark on the pump body aligns with the aligning mark on the oil pump control lever Reference tip alignment within 1mm of index mark on open side is acceptable Start and idle the engine then slowly open the throttle to increase engine rpm and check the operation of the oil pump control lever If adjustment is necessary adjust the oil pump control cable by loosening the control cable lock nut and turning the adjusting nut After adjustment tighten the lock nut KYMCO Mongoose KXR 90 50 Fuel Filter Throttle Lever Lock Nut Adjuster Control Lever Aligning Mark Lock Nut Adjusting Nut 3 4 KYMCO 3 IISPECTION ADJUSTMENT Mongoose KXR 90 50 Reference tip alignment within 1mm of index mark
99. o vehicles already in service ad well as new vehicles that are being prepared for sale All service technicians should be familiar with this entire chapter Initial Item Remarks 6 month Valves Check valve clearance Adjust if Mongoose KXR 50 necessary Check condition Clean or replace if necessary Spark plug Air clearance Clean Replace if necessary Check idle speed starter operation Adjust if necessary Check fuel hose for cracks or damage Replace if necessary Replace Warm engine before draining Engine oil filter screen Cl Replace if Mongoose KXR 50 ean Replace if necessary Check oil leakage Replace every 12 months Check operation Adjust if necessary Check operation replace if damage or excessive wear Check balance damage runout Replace if necessary Check bearings assembly for looseness damage Replace if damaged Check operation replace if damage Check toe in adjust if necessary Transmission oil Brake system E Steering system Knuckle shafts Lubricate every 6 months E Check all chassis fittings and Fitting Fasteners fasteners Correct if necessary e In the interest of safety we recommend these items should be serviced only by an authorized KYMCO motorcycle dealer 3 3 3 IISPECTION ADJUSTMENT FUEL LINE Check the fuel tubes and replace a
100. ol E016 KYMCO 11 CRANKCASE CRANKSHAFT Mongoose KXR 90 50 CRANKCASE ASSEMBLY Dowel Pins Install the dowel pins and a new gasket to the crankcase mating surface Assemble the crankcase halves Crankshaft amp crankcase install tool E024 The distance between the right crankcase oil seal and crankcase surface is about 12 5 0 5 mm When installing the oil seal be careful to press it with even force 11 11 KYMCO 11 CRANKSCASE CRANKSHAFT Mongoose KXR 90 50 The distance between the left crankcase oil seal and crankcase surface is about 1 0mm Oil Seal Install and tighten the crankcase attaching bolts After assembly check the crankshaft for smooth operation 11 12 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 FRONT WHEEL FRONT BRAKE FRONT SUSPENSION STEERING SYSTEM SERVICE INFORMATION 1959 12 4 PRONT BRAKE 12 8 FRONT SUSPENSION eee 12 10 RN 12 13 TIE RODS eric oc 12 17 12 0 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 gt Rd o 9 ON 12 1 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 SERVICE INFORMATION GENERAL INSTRUCTIONS Remove the machine frame covers before removing th
101. ompression is high it indicates that carbon deposits have accumulated on the combustion chamber and the piston head 3 7 KYMCO 3 IISPECTION ADJUSTMENT Mongoose KXR 90 50 VALVE CLEARANCE Mongoose KXR 90 JInspect adjust valve while engine is cold below 35 Disconnect the oil recycle tube at the cylinder head cover Remove the four bolts and cylinder head cover Cylinder Head Cover SN Remove the two screws and two bolts then remove the fan cover Turn the cooling fan clockwise so that the mark on the flywheel aligns with the index mark on the crankcase to bring the round hole on the camshaft gear facing up to the top dead center on the compression stroke Bolts Inspect and adjust the valve clearance Valve Clearance IN 0 1mm EX 0 1mm Loosen the lock nut and adjust by turning the adjusting nut Tappet adjuster E012 Check valve 1 again after the lock nut is tightened CARBURETOR IDLE SPEED e The engine must be warm for accurate idle speed inspection and adjustment Round Hole Punch Marks Air Screw Warm up the engine before this operation Start the engine and connect a tachometer Turn the throttle stop screw to obtain the specified idle speed Idle Speed Mongoose KXR 90 1700 100rpm Mongoose KXR 50 2000 100rpm When engine misses Throttle S
102. on open side is acceptable However the aligning mark on the control lever must never be on the closed side of the index mark otherwise engine damage will occur because of insufficient lubrication If the oil pump is not synchronized properly the following will occur Excessive white smoke or hard starting due to pump control lever excessively open e Seized piston due to pump control lever insufficiently open AIR CLEANER AIR CLEANER REPLACEMENT CLEANING To replace the air cleaner Mongoose KXR 90 Remove the seat See page 2 3 2 Remove the five screws and then remove air filter case cover 3 Remove the air filter element and separate it from the box Air Filter Element 3 5 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 Screws To replace the air cleaner Mongoose KXR 50 1 Remove the five screws and air filter case cover Air Filter Case Cover 2 Remove the air filter element and separate it from the box To clean the air filter element 1 Wash the element gently but thoroughly in solvent Use parts cleaning Solvent only use gasoline or low flash point solvents which may lead to a fire or explosion 2 Squeeze the excess solvent out of the filter and let it dry Do not twist or wring out the foam element This could damage the foam material 3 Inspect the element If damaged replace diis it di 4 Apply quality foam air fi
103. or left even though the handlebar is positioned straight which may lead to mishandling and accident e After setting the toe in to specification run the machine slowly for some distance with hands placed lightly on the handlebar and check that the handlebar responds correctly If not turn either the right or left tie rod within the toe in specification Tie rod End Nuts 3 15 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 WHEELS TIRES Check the tires for cuts imbedded nails or other damages Check the tire pressure Tire pressure Should checked when tires are cold TIRE PRESSURE D me 0 22kgf cm Rear 0 22kgf cm TIRE SIZE Mongoose KXR 90 Front 18 7 8 Rear 18 9 8 TIRE SIZE Mongoose KXR 50 Front 16 8 7 Rear 16 8 7 Check the front wheel hub nut for looseness Check the rear wheel hub nut for looseness If the axle nuts are loose tighten them to the specified torque Torque Front 5 5 6 5kgf m Rear 6 0 8 0kgf m WHEEL INSPECTION Inspect the tire surfaces Replace if wear or damage Tire wear limit 3 0mm It is dangerous to ride with a worn out tire When a tire wear is out of specification replace the tire immediately 3 16 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 Inspect the wheel Replace if damage or bends Always balance the wheel when a tire or wheel has been changed or replaced e Never attempt even small
104. ose battery connection e Faulty regulator rectifier e Charging system failure e Faulty A C generator e Faulty regulator rectifier 14 3 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 BATTERY REMOVAL Remove seat See page 2 3 Remove the battery cover by removing the mount bolts Make sure the ignition switch is OFF Remove the battery by removing the bolts Battery Cover Negative Cable Positive Cable First disconnect the battery negative cable and then the positive cable When disconnecting the battery positive cable do not touch the frame with tool otherwise it will cause short circuit and sparks to fire the fuel The installation sequence is the reverse of removal V First connect the positive cable and then negative cable to avoid short circuit BATTERY VOLTAGE OPEN CIRCUIT VOLTAGE INSPECTION Remove the seat See page 2 3 Disconnect the battery cables Measure the voltage between the battery terminals Fully charged 13 1V Undercharged 12 3V max Battery charging inspection must be performed with a voltmeter 14 4 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 CHARGING Connect the charger positive cable to the battery positive 4 terminal Connect the charger negative cable to the battery negative terminal Charging Lam G P V e Keep fla
105. ould be engaged If not the starter clutch is faulty Replace it When turning the wheel gear counterclockwise 2 the wheel gear should turn freely If not the starter clutch is faulty Replace it 2 KYMCO 16 STARTING SYSTEM Mongoose KXR 90 50 Starter Pinion STARTER PINION Mongoose KXR 50 REMOVAL Remove the left crankcase cover Remove the drive pulley Refer to chapter 9 Remove the starter pinion cover Remove the starter pinion 4 Starter Cover Shaft Forcing Parts INSPECTION Inspect the starter pinion seat for wear Inspect the starter pinion for smooth operation Inspect the starter pinion shaft forcing parts for wear and damage INSTALLATION Apply a small amount of grease to the starter pinion teeth Install the starter pinion in the reverse order of removal Starter Pinion 16 9 KYMCO 17 BULBS REMOVAL INSTRUMENT HORN Mongoose KXR 90 50 BULBS REMOVAL INSTRUMENT HORN BULBS REMOVA 2 17 1 INSTRUMENT ON ROAD ONLY 17 4 HORNON ROAD ONL Y t ee 17 4 17 0 KYMCO 17 BULBS REMOVAL INSTRUMENT HORN Monsoose KXR 90 50 Headlight Wire Coupler BULBS REMOVAL HEADLIGHT ON ROAD ONLY Remove the front fender See page 2 5 Disconnect the headlight wire coupler Remove the rubber boot from the bulb socket Relax the lock clip to remove the bulb an
106. r O ring and install the cylinder head cover Install and tighten the cylinder head cover bolts Torque 0 8 1 2kgf m sure to install O ring into groove properly CAMSHAFT CAMSHAFT HOLDER REMOVAL Remove the cylinder head cover Refer to the CYLINDER HEAD COVER REMOVAL Remove the cam chain tensioner cap bolt and the O ring Turn the cam chain tensioner screw clockwise to tighten it Turn the cooling fan clockwise so that the mark on the flywheel aligns with the index mark on the crankcase to bring the round hole on the camshaft gear facing up to the top dead center on the compression stroke AV Round Hole Punch Marks 7 4 7 CYLINDER HEAD VALVES KYMCO Mongoose KXR 90 Mongoose KXR 90 50 Nuts and Washers Remove the four camshaft holder nuts and washers Diagonally loosen the cylinder head nuts in 2 or 3 times Camshaft Holder Remove the camshaft holder and dowel pins Remove the camshaft gear from the cam chain and remove the camshaft Rocker Arms CAMSHAFT HOLDER DISASSEMBLY Take out the valve rocker arm shafts using a 5mm bolt Remove the valve rocker arms and arm shafts Rocker Arm Shafts 7 5 7 CYLINDER HEAD VALVES KYMCO Mongoose KXR 90 Mongoose KXR 90 50 Camshaft Holder Rocker Arm CAMSHAFT HOLDER INSPECTION Inspect the camshaft holder for wear or S damage a 2d Inspect the rocker arm shaft for blue
107. rake caliper Tw P Remove the pistons from the brake caliper Use compressed air to press out the pistons through the brake fluid inlet opening and place a shop towel under the caliper to avoid contamination caused by the removed pistons Brake Caliper Holder Push the piston oil seals inward to remove Piston Oil Seals them Clean each oil seal groove with brake fluid Be careful not to damage the piston surface 13 20 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 INSPECTION Inspect the caliper cylinder wall and piston surface for scratch corrosion or other damages If any abnormal condition is noted replace the caliper ps 7 4 ASSEMBLY Clean all removed parts Apply silicon grease to the pistons and oil seals Lubricate the brake caliper cylinder inside wall with brake fluid Install the oil seals and then install the brake caliper pistons with the grooved side facing out Install the piston with its outer end protruding 3 5mm beyond the brake caliper Wipe off excessive brake fluid with a clean shop towel Apply silicon grease to the brake caliper holder pin and caliper inside Install the brake caliper holder 13 21 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 Tube With Groove Aligning The Fluid INSTALLATION Fm Connect the brake fluid tube to the brake caliper aligning the fluid tub
108. repairs to the wheel e Ride conservatively after installing a tire to allow it to seat itself properly on the rim DRIVE CHAIN SLACK ADJUSTMENT Before checking and or adjusting rotate the rear wheels several revolutions and check slack at several points to find the tightest point Check and or adjust the chain slack with the rear wheels in this tightest position Too little of chain slack will overload the engine and other vital parts keep the slack within the specified limits Place the machine on a level place Wheels should be the ground without the rider on it Check drive chain slack A Adjust if out of specification Drive chain slack Approximately 10 20mm Adjust drive chain slack Elevate the rear wheels by placing a suitable stand under the rear of frame Support the machine securely so there is no daneer of it falline over Loosen the upper and lower axle holding bolts Hub Stopper Nut 3 17 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 Turn the adjusting nut to decrease or increase chain slack Retighten the upper and lower axle holding bolts Torque 6 0 8 0kgf m Adjusting Nut Drive chain cleaning and lubrication The drive chain is equipped with rubber O rings between the chain plates Steam cleaning high pressure washes and certain solvents can damage these O rings Use only kerosene to clean the drive chain Wipe it dry
109. rface of the tie rod end Replace it if pitting wear or damage Lock Nut Indentation Surface Lock Nut Adjust the tie rod length Adjustment steps The following procedures are done on both tie rods right and left Loosen the lock nuts Adjust the tie rod length by tuning both tie rod ends Tie rod length 254 5 255 5mm 12 17 12 FRONT WHEEL FRONT BRAKE FRONT 4O KYMCO SUSPENSION STEERING SYSTEM Mongoose KXR 90 50 Set the rod end steering column side in an angle where the indentation surface of the To Knuckle Arm tie rod is parallel to the rod end shaft and then tighten the lock nut Torque 2 0 3 0kgf m Set the other rod end knuckle arm side in an angle as shown right hand tie rod and left had tie rod and then tighten the lock nut Right Side Rod end tie rod angle A 15 3 Torque 2 0 3 0kgf m To Knuckle Arm After making adjustment on both tie rods be sure to mark them R and L for identification The threads on both rod end must be of the same length Indentation Surface INSTALLATION Install the tie rod and tighten the nuts Torque 2 5 3 5kgf m Be sure that the rod end on the indentation surface side 1s connected to the steering knuckle Install the cotter pins and band ends of cotter pin Always use anew Refer to the TOE IN ADJUSTMENT section in the CHAPTER 3 to adjust toe in 12 18 13 REAR WHEEL
110. rn screw out ixture too lean turn screw in Correctly adjusted Incorrectly adjusted Check carburetor gasket i for air leaks Deteriorated arburetor not securely tightened Damaged insulator rubber Remove spark plug and install it into spark plug to test spark by connecting it to engine ground Faulty or fouled spark plug Faulty CDI unit aulty generator aulty ignition coil Broken or shorted spark plug wire aulty ignition switch Weak or inter mittent spark Good spark 1 27 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 POOR PERFORMANCE AT HIGH SPEED Inspection Adjustment Probable Cause aulty CDI unit aulty pulser coil Check valve clearance Improperly adjusted valve Correctly adjusted Incorrectly adjusted clearance Worn valve seat fuel supply Empty fuel tank logged fuel tube or filter logged Fuel tank cap breather hole Check carburetor jets for clogging i Not clogged Clogged Clean and unclog Check valve timing gt not aligned Check Valve spring tension Weak spring Faulty spring 1 28 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 POOR CHARGING BATTERY OVER DISCHARGING OR OVERCHARGING Undercharging Inspection Adjustment Probable Cause O Start engine and test limit voltage of terminals Normal voltage Voltage does no
111. se KXR 90 50 Rear Swing Arm Axle Rear Axle Hub Driven Sprocket Collar Oil Seal Bearing 1 17 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 CABLE amp HARNESS ROUTING Throttle Cable Rear Brake Cable Fluid Hose Rear Stop Switch Wire Kill Switch Wire Safety Qu e cog _ ey fet eae T i DESSA X oy JLEZ 9 P d SN as Switch Wire Front Brake Cable Rear Stop Switch Wire Front Stop Switch Wire Kill Switch Wire Safety EE Ignition Switch Coupler v 2 HR ME Handlebar Switch Coupler Front Stop Switch Wire IN ON REG REC Wire REG REC Headlight Wire Coupler Em i m FA of 1 8 2 or aN S S Ignition Coil 2 M 1 oN lt 4 Xl y 4 LN SL 775 TE Rear Brake Cable Fluid Hose Front Brake Cable 1 18 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 Oil Level Switch Wire Starter Motor Wire Mongoose KXR 50 Ignition Coil i Ignition Coil Wire SS 8 _ 9 J J Lots AN 7 E A 5 Outlet Tube Mongoose KXR 50 A C G Wire 1 19 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 able Autobystar
112. should be recharged every 3 months A new battery filled with electrolyte will generate voltage within a certain time and it should be recharged when the capacity is insufficient Recharging a new battery will prolong its service life e Inspect the charging system according to the sequence specified in the Troubleshooting Do not disconnect and soon reconnect the power of any electrical equipment because the electronic parts in the regulator rectifier will be damaged Turn off the ignition switch before operation e It is not necessary to check the MF battery electrolyte or fill with distilled water Check the load of the whole charging system Do not quick charge the battery Quick charging should only be done in an emergency Remove the battery from the motorcycle for charging e When replacing the battery do not use a traditional battery e When charging check the voltage with an voltmeter SPECIFICATIONS Voltage Battery 20 14 2 14 BATTERY CHARGING SYSTEM C KYMCO A C GENERATOR Mongoose KXR 90 50 TESTING INSTRUMENTS Electric tester YF 3051 TROUBLESHOOTING No power Intermittent power Dead battery Loose battery cable connection e Disconnected battery cable Loose charging system connection e Fuse burned out Loose connection or short circuit in Faulty ignition switch lighting system Low power Charging system failure e Weak battery Loose broken or shorted wire or connector e Lo
113. sor and install drive Plate nut ut Set the clutch spring compressor in a vise and tighten the drive plate nut to the specified Collar OFF ROAD Clutch torque Torque 5 0 6 0kgf m Be sure to use a clutch spring compressor to avoid spring damage Special Clutch Spring Compressor E027 Lock Nut Wrench 39mm Clutch Spring Compressor 9 14 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 INSTALLATION Install the clutch driven pulley and driven belt onto the drive shaft Keep grease off the drive shaft Install the clutch outer Hold the clutch outer with the universal holder Install and tighten the clutch outer nut Torque 3 5 4 5kg m Special Universal Holder E017 9 15 10 FINAL REDUCTION KYMCO TRANSMISSION SYSTEM Mongoose KXR 90 50 SERVICE INFORMATION 10 2 TRANSMISSION CASE COVER 10 3 10 0 10 FINAL REDUCTION KYMCO TRANSMISSION SYSTEM Mongoose KXR 90 50 10 1 10 FINAL REDUCTION TRANSMISSION SYSTEM SERVICE INFORMATION GENERAL INSTRUCTIONS KYMCO Mongoose KXR 90 50 e The transmission system can be serviced with the engine installed in the frame e When replacing the drive shaft use a special tool to hold the bearing inner race for this operation SPECIFICATIONS Specified Oil GEAR OIL SAE 90 Oil Capacity
114. sor and disassemble the clutch driven pulley assembly Remove the seal collar Seal Collar 4 Dust Movable Driven Pull out the three guide roller pins and guide pus rollers Remove the movable driven face from the driven face Guide Roller Pins 9 10 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 Measure the clutch lining thickness Service Limit Mongoose KXR 90 1 5mm replace if below Mongoose KXR 50 1 0mm replace if below INSPECTION Measure the driven face spring free length Service Limit Mongoose KXR 90 137 5mm below Mongoose KXR 50 92 8mm below Check the driven face for wear or damage Measure the driven face O D Service Limit 33 94mm below 9 11 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 Check the movable driven face for wear or damage Measure the movable driven face I D Service Limit 34 06mm over DRIVEN PULLEY FACE BEARING REPLACEMENT Drive the inner needle bearing out of the driven pulley face Discard removed bearing replace with a new one Remove the snap ring and drive the outer bearing out of the driven face Discard removed bearing replace with a new one Bearing Puller E037 Outer Bearing Apply grease to the outer bearing Drive a new outer bearing into the driven face with the sealed end facing up Seat the snap ring in its groove Apply grease to the driven fac
115. ssing the piston rings Be careful not to damage the piston Install the cylinder head Torque 0 8 1 2kg m The installation sequence is the reverse of removal 8 17 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 DRIVE AND DRIVEN PULLEYS SERVICE INEFEORMATION up lero ee ad to orte 9 2 LEFT CRANKCASE COVER KICK STARTER 9 4 DRIVEPULLEY G 9 7 CLUTCH DRIVEN PULLEY daten Sue 9 9 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 9 1 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 SERVICE INFORMATION GENERAL INSTRUCTIONS e The drive pulley clutch and driven pulley can be serviced with the engine installed in the frame e Avoid getting grease and oil on the drive belt and pulley faces Remove any oil or grease from them to minimize the slipping of drive belt and drive pulley SPECIFICATIONS Mongoose KXR 90 Movable drive face bushing 23 989 24 052 24 06 Drive face collar O D 23 96 23 974 23 94 Drive belt width 16 5 Clutch lining thickness SPECIFICATIONS Mongoose KXR 50 9 2 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 TORQUE VALUES Drive face nut 5 5 6 5kgf m Mongoose KXR 90 3 5 4 5kgf m Mongoose KXR 50 Clutch outer nut 3 5 4 5kgf m Drive plat nut 5 0 6 0kgf m SPECIAL TOOLS Universal holder E017 Cl
116. t Dead battery increase Faulty battery Measure resistance between generator gt coil terminals Faulty generator coil Resistance too high Broken yellow wire wires ito regulator rectifier coupler red wire and R battery wire to engine ground and test voltage Normal voltage Broken red wire Check regulator rectifier i coupler for loose i gt i connection connected coupler generator Overcharging Inspection Adjustment Probable Cause O Connect battery wire to regulator rectifier coupler green wire and battery wire to engine ground and test voltage Battery has no nemin with ignition SWitc Battery has voltage with ignition Broken green wire switch Check regulatorrectifier coupler for loose connection Poorly connected coupler Faulty regulator rectifier 1 29 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 NO SPARK AT SPARK PLUG Inspection Adjustment Probable Cause Spark plug high tension wire gt for looseness Check CDI unit coupler for looseness Measure resistance between terminals of CDI unit coupler Check related parts Faulty ignition switch Weak battery Faulty pulser coil Faulty ignition coil Faulty charging system Broken wir
117. t and then remove the shock absorber INSPECTION Check the tightening torque of the pivot shaft swing arm securing nut Torque 6 0 8 0kgf m 13 10 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 Check the swing arm side play by moving it from side to side If side play noticeable check the inner collar bushing and thrust cover Check the swing arm vertical movement by moving it up and down If vertical movement is tight binding or rough to check the inner collar bushing and thrust cover INSPECTION Inspect the shock absorber rod Replace the shock absorber assembly if bends or damage Inspect the shock absorber Replace the shock absorber assembly if oil leaks Inspect the spring Replace the shock absorber assembly if fatigue Move the spring up and down 13 11 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 Swing Arm REAR SWING ARM REMOVAL Remove the nut and pivot shaft then remove swing arm Remove the three bolts and chain guard DO bain Remove the drive chain Remove thrust covers and collar Thrust Covers 13 12 13 REAR WHEEL SWING ARM KYMCO HYDRAULIC BRAKE Mongoose KXR 90 50 INSPECTION Roll the axle on a flat surface to inspect the pivot shaft Replace it if bends Do not attempt to straighten a bent axle Collar Chain Guide Inspect the swing arm Replace it if
118. t edge and feeler gauge Service Limit 0 05mm repair or replace if over VALVE SPRING INSPECTION Measure the free length of the inner and outer valve springs Service Limit Inner 30 8mm replace if below Outer 33 5mm replace if below KYMCO Mongoose KXR 90 50 XO j m 7 10 7 CYLINDER HEAD VALVES KYMCO Mongoose KXR 90 Mongoose KXR 90 50 Measure compressed force valve spring and installed length Replace if out of specification Service limits IN 3 47 4 27kg at 26 0mm 8 29 10 19kg at 29 0mm Check the intake manifold and O rings for wear or damage O ring 7 11 7 CYLINDER HEAD VALVES C KYMCO Mongoose KXR 90 Mongoose KXR 90 50 ASSEMBLY Install the valve spring seats and oil seal Be sure to install new oil seal Lubricate each valve with engine oil and insert the valves into the valve guides Install the valve springs and retainers Compress the valve springs using the valve spring compressor then install the valve cotters When assembling a valve spring compressor must be used e Install the cotters with the pointed ends facing down from the upper side of the cylinder head Valve Spring Compressor E040 Tap the valve stems gently with a plastic hammer for 2 3 times to firmly seat the cotters T Be careful not to damage the valves INSTALLATION Install the dowel pins and a new cylinder head gask
119. ted Valve train lubricated Valve train not properly lubricated properly gt Engine does not Engine overheats overheats Rapidly accelerate run at high speed Engine does not knock Engine knocks KYMCO Mongoose KXR 90 50 Probable Cause Clogged air cleaner Restricted fuel flow Clogged fuel tank cap breather hole Clogged exhaust muffler arburetor fuel level too low Faulty ignition unit Faulty pulser coil Improper valve clearance adjustment xcessively worn valve seat protruded valve stem Improper valve and seat contact Worn cylinder and piston rings Leaking cylinder head gasket Improper valve timing Clean and unclog ouled spark plug Incorrect heat range plug Oil level too high Oil level too low Oil not changed logged oil line Faulty oil pump Worn cylinder and piston rings Mixture too lean Poor quality fuel Excessive carbon build up in combustion chamber Ignition timing too early Excessive carbon build up in combustion chamber Poor quality fuel lutch slipping Mixture too lean Ignition timing too early 1 26 KYMCO 1 GENERAL INFORMATION Mongoose KXR 90 50 POOR PERFORMANCE ESPECIALLY AT IDLE AND LOW SPEEDS Inspection Adjustment Probable Cause aulty ignition unit Faulty pulser coil Correct timing Incorrect timing Check carburetor air i screw adjustment 1xture too rich tu
120. ter Wire Fuel Tube Resistor Air Inlet Hose Harness Wire Battery Negative x Li x o SLC 9 o f 3f LS A o Eee 9 5 227 P ET v 22224 uev Oil Pump Control Cable Mongoose KXR 50 Battery Positive Ignition Coil Wire Taillight Coupler Rear Brake Cable Fluid Hose 1 20 KYMCO Mongoose KXR 90 50 1 GENERAL INFORMATION WIRING DIAGRAM Mongoose KXR 90 OFF ROAD FR RR STOPSW STOPSW 12V 5AH BATTERY Hi 2 TUBE BLACK vu KILL SWSTARTER SWFRAME 7 52 120 STARTER MOTOR DIMMER SW EARTH 30W 5w COLOR COMB GROUND MARKING BLACK BR BROWN DIMMER SW COMB SW Tigml bef ig koc olo B Y YELLOW O ORANGE lolol oulo Io Eee ll el ww lsslswy Earl SWUNIT KILL SAFETY KILL SW TAIL STOP LIGHT 12V 518W SWUNIT KILL SIG SAFETY IGN COIL SPARK PLUG 1 21 KYMCO Mongoose KXR 90 50 1 GENERAL INFORMATION WIRING DIAGRAM KXR 90 ON ROAD RH FR WINKER FR 12V 10W STOP SW COMB sw START RELAY SB G RM VV YG RAGE 1 MY B lt HIGH BEAM PILOT G 12 12W
121. the O rings and diaphragm must be removed first to avoid damage Then clean with compressed air e When the machine is not used for over one month drain the residual gasoline from the float chamber to avoid erratic idling and clogged slow jet due to deteriorated fuel SPECIFICATIONS ue 3 1 B 5 2 5 FUEL SYSTEM SPECIAL TOOL Float level gauge TROUBLESHOOTING Engine cranks but won t start e No fuel in tank e No fuel to carburetor e Cylinder flooded with fuel e No spark at plug Clogged air cleaner e Intake air leak Improper throttle operation Engine idles roughly stalls or runs poorly e Faulty auto bystarter Ignition malfunction e Faulty carburetor Poor quality fuel e Lean or rich mixture e Incorrect idle speed Misfiring during acceleration e Faulty ignition system e Faulty carburetor Backfiring at deceleration e Float level too low e Incorrectly adjusted carburetor e Faulty exhaust muffler 5 3 KYMCO Mongoose KXR 90 50 Engine lacks power e Clogged air cleaner e Faulty carburetor e Faulty ignition system Lean mixture e Clogged carburetor fuel jets e Float level too low e Intake air leak e Clogged fuel tank cap breather hole e Bent kinked or restricted fuel line Rich mixture e Float level too high e Clogged air jets e Clogged air cleaner KYMCO 5 FUEL SYSTEM Mongoose KXR 90 50 FUEL TANK REMOVAL pensis e Keep sparks and flam
122. top Screw adjust the air screw 3 8 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 ENGINE OIL Mongoose KXR 90 OIL LEVEL Remove the two bolts and right side cover Place the machine on a level place Warm up the engine for several minutes and stop it Remove the dipstick and wipe it off with a clean rag Insert the dipstick in the filler hole without screwing it in ler Cap Run the engine for 2 3 minutes and check the oil level after the engine is stopped for 2 3 minutes Remove the dipstick and inspect the oil level The oil level should be between the maximum and minimum marks If the level is low add oil to raise it to the proper level Minimum Level Mark Dipstick Oil Filler Cap ENGINE OIL REPLACEMENT Place the machine on a level place EE Warm up the engine for several minutes and ale stop it Place a container under the engine Remove right side cover Remove the oil filler cap and drain plug to drain the oil Reinstall the drain plug and tighten the drain plug to specification Torque 2 0 3 0kgf m Fill the engine with oil and install the oil filler cap Warm up the engine for several minutes at idle speed Check for oil leakage while warming up Be sure no foreign material enters the crankcase Oil Capacity At disassembly 0 8L At change 0 7L 3 9 KYMCO 3 INSPECTION ADJUSTMENT Mongoose KXR 90 50 ENGINE OIL REPLACEMENT A
123. ures Make sure that the pump shaft rotates freely without binding Install the oil pump with the arrow on the pump body facing up and fill the oil pump with engine oil before installation Screws KYMCO 4 LUBRICATION SYSTEM Mongoose KXR 90 50 OIL PUMP BLEEDING Mongoose KXR 50 Air in the oil tubes will block oil flow and result in severe engine damage e Bleed air from the oil tubes and oil pump whenever the oil tubes or pump have been removed or there is air in the oil tubes OIL INLET LINE OIL PUMP BLEEDING Fill the oil tank with recommended oil Place a shop towel around the oil pump Disconnect the oil inlet tube from the oil pump and clip it Fill the oil pump with oil by squirting clean oil through the joint About 3cc Fill the oil line with oil and connect it to the oil pump Bleed air from the oil inlet tube first then bleed air from the oil outlet line OIL OUTLET LINE BLEEDING 1 Disconnect the oil outlet tube and bend it into U shape Force air out of the tube by filling it with oil 2 Start the engine and allow it to idle with the oil control lever in the fully open position Visually check the oil flow 3 If there is no oil flowing out within 1 minute bleed air from the oil inlet tube and oil pump Oil Outlet Line e Never run the engine in a closed area Do not increase the engine speed at will 4 9 KYMCO 4 LUBRICATION SY
124. ust muffler Refer to the EXHAUST MUFFLER REMOVE section in the chapter 2 Intake Manifold Remove the two nuts and then remove the carburetor intake manifold Remove the cooling fan cover 5 14 8 Remove the engine cover bolts and screws Separate the engine cover joint claws CYLINDER HEAD DISASSEMBLY Remove the valve spring cotters retainers Valve Cotter Retainer Springs Springs Seat springs spring seats oil seals and valves using a valve spring compressor e sure to compress the valve springs with a valve spring compressor e Mark all disassembled parts to ensure correct reassembly Valve Spring Compressor E040 Spring Compressor OilSeal Valve 7 9 7 CYLINDER HEAD VALVES Mongoose KXR 90 VALVE VALVE GUIDE INSPECTION Inspect each valve for bending burning scratches or abnormal stem wear If any defects are found replace the valve with a new one Check valve movement in the guide Measure each valve stem O D Measure each valve guide I D Subtract each valve stem O D from the corresponding guide I D to obtain the stem to guide clearance Service limits IN 0 06mm replace if over EX 0 08mm replace if over If the stem to guide clearance exceeds the service limits replace the cylinder head as necessary CYLINDER HEAD INPECTION Check the spark plug hole and valve areas for cracks Check the cylinder head for warpage with a straigh
125. utch spring compressor E034 Bearing puller E037 Oil seal and bearing install E014 TROUBLESHOOTING Engine starts but motorcycle won t move Lack of power e Worn drive belt e Worn drive belt e Broken ramp plate e Weak driven face spring e Worn or damaged clutch lining Worn weight roller e Broken driven face spring Fouled drive face Engine stalls or motorcycle creeps e Broken clutch weight spring 9 3 KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 Left Crankcase Cover LEFT CRANKCASE COVER KICK STARTER REMOVAL Remove left foot board See page 2 7 Remove the eight left crankcase cover bolts and left crankcase cover Remove the gasket and dowel pins Use specified genuine parts for replacement KICK STARTER DISASSEMBLY Remove the Kick lever from the kick starter spindle Remove the circlip and washer from the kick starter spindle Washer Kick Starter Spindle Friction Spring Remove three bolts at the kick starter spindle cover then remove kick starter spindle cover Gently turn the kick starter spindle to remove the starter driven gear together with the friction spring Remove the kick starter spindle and return spring from the left crankcase cover Remove the kick starter spindle bushings Kick Starter Spindle KYMCO 9 DRIVE AND DRIVEN PULLEYS Mongoose KXR 90 50 Spindle Return Spring INSPECTION Inspect the kick starter spindle and gear for wear or damage
126. ve false readings Testing instrument YF 3501 e If the dry battery in the tester is weak the readings will be incorrect In this case check the dry battery elow pe p Green Replace the regulator rectifier 1 the readings are not within the specifications in the table 14 7 14 BATTERY CHARGING SYSTEM KYMCO A C GENERATOR Mongoose KXR 90 50 Coil Wire X gt GENERATOR CHARGING COIL The inspection of generator charging coil can be made with the engine installed INSPECTION Disconnect the A C generator 2P connector Measure the resistance between the A C generator white wire and engine ground with an electric tester YF 3501 tester Standard 2 20 20 Replace the A C generator charging coil if the reading is not within the specifications A C GENERATOR LIGHTING COIL The inspection of generator lighting coil can be made with the engine installed INSPECTION Disconnect the A C generator 2P connector Measure the resistance between the A C generator yellow wire and engine ground with an electric tester 3501 tester Standard 3 10 20 Replace the A C generator lighting coil if the reading is not within the specifications RESISTOR INSPECTION Remove the front covers 2 2 Measure the resistance between the resistor lead and engine ground Resistances Mongoose KXR 90 SW1

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