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the full service manual - Tulsa Engine Warehouse

1. 16 690 01 Rev KohlerEngines com A Fixed Guard B Air Cleaner Cover C Debris Screen D Blower Housing E Hose Clamp F Fuel Pump G Hose Clip H Fuel Line l Fuel Filter J Oil Filter K Outer Baffle L Electric Starter M Inner Baffle N Ignition Module Intake Manifold P Carburetor Q Gasket R Air Cleaner Base S Paper Element T Rectifier Regulator U Dipstick Tube V Oil Fill Dipstick W Breather Hose X Precleaner Y Retractable Starter 67 Reassembly Install Ignition Modules Install Rectifier Regulator if equipped 1 Rotate flywheel to position magnet away from ignition module bosses 2 CDI modules are installed with spark plug lead wire from module always away from cylinder On cylinder 1 single kill tab should be towards you On cylinder 2 single kill tab should be away from you in MDI modules are installed with flat side out towards you 3 Install each ignition module to crankcase bosses Slide modules up as far away from flywheel as possible and snug screws to hold them in position 4 Rotate flywheel to position magnet directly under 1 ignition module 5 Insert a 0 25 mm 0 009 in flat feeler gauge between magnet and ignition module Loosen screws enough to allow magnet to pull module down against feeler gauge 6 Torque screws to 4 0 6 2 N m 35 55 in Ib Repeat steps 4 through 6 for other ignition module 8 Rotate flywheel back and forth checking for clearance betwee
2. gt 0 A Wire Gauge B Spark Plug C Ground Electrode D Gap NOTE Do not clean spark plug in a machine using abrasive grit Some grit could remain in spark plug and enter engine causing extensive wear and damage Engine misfire or starting problems are often caused by a spark plug that has improper gap or is in poor condition Engine is equipped with following spark plugs Gap 0 76 mm 0 03 in Thread Size 14 mm Reach 19 1 mm 3 4 in Hex Size 15 9 mm 5 8 in Refer to Maintenance for Repairs Service Parts Service Clean out spark plug recess Remove plug and replace 1 Check gap using wire feeler gauge Adjust gap to 0 76 mm 0 03 in 2 Install plug into cylinder head 3 Torque plug to 27 N m 20 ft Ib 16 690 01 Rev Inspect each spark plug as it is removed from cylinder head Deposits on tip are an indication of general condition of piston rings valves and carburetor Normal and fouled plugs are shown in following photos Normal Fa Plug taken from an engine operating under normal conditions will have light tan or gray colored deposits If center electrode is not worn plug can be set to proper gap and reused Worn On a worn plug center electrode will be rounded and gap will be greater than specified gap Replace a worn spark plug immediately Wet Fouled A wet plug is caused by ex
3. LE 6 08 55 8 EL Sai H MD eR ee 72 0 ENGINE 2 83 MOUNTING Lem SURFACE PORT 2 443 2 3798 17 45 14 94 9 42 t ENGINE NG SURFACE Bie MOUTNING oiL Fitter MOLE A OIL FILTER SIDE 6 KohlerEngines com 16 690 01 Rev ENGINE IDENTIFICATION NUMBERS Specifications Kohler engine identification numbers model specification and serial should be referenced for efficient repair ordering correct parts and engine replacement Model 5 i ed etae ZT710 Confidant Engine Numerical Designation Specification ZT710 0001 nite Sate aon ae 4323500328 Year Manufactured Code Factory Code Code Year 43 2013 44 2014 45 2015 GENERAL SPECIFICATIONS ZT710 ZT720 ZT730 ZT740 Bore 83 mm 3 27 in Stroke 67 mm 2 64 in 69 mm 2 72 in Displacement 725 cc 44 cu in 747 cc 46 cu in Oil Capacity refill 1 6 1 8 L 1 9 2 1 qt Maximum Angle of Operation full oil level 25 TORQUE SPECIFICATIONS 5 ZT710 ZT720 ZT730 ZT740 Baffle and Sheet Metal into Aluminum M5 Thread Forming Fasteners 8 5 N m 75 in Ib into new hole 4 0 N m 35 in Ib into used hole M6 Thread Forming Fasteners 10 7 N m 95 Ib into new hole m 65 in Ib into used hole Blower Housing and Sheet Metal M3 HI LO Screw 2 3 20 in l
4. Install Fuel Pump Ab waRNING Explosive Fuel can cause fires and severe burns d L Do not fill fuel tank while engine is hot or running Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupied buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent 70 KohlerEngines com A Outlet Fuel Line B Pulse Hose C Inlet Fuel Line D Fuel Line Clamp E Fuel Filter F Fuel Pump NOTE If a new fuel pump is being installed make sure orientation of new pump is consistent with removed pump Internal damage may occur if installed incorrectly 1 Connect pulse hose to valve cover Valve cover should be situated between 2 formed lips on pulse hose 2 Attach pulse hose to fuel pump and secure with a clamp Mount fuel pump to blower housing with screws Torque screws to 2 8 N m 25 in Ib 3 Connect inlet and outlet fuel lines to pump Route inlet fuel line through fuel line clamp if used as shown Install Muffler 1 Install muffler and attaching hardware to muffler bracket Torque screws to 9 9 N m 88 in Ib 2 Install M8 nuts or 5 16 18 head capscrews based on head design to secure muffler Torque nuts to 24 4 N m 216 in Ib or capscrews to 16 9 N m 150
5. before servicing Accidental Starts can cause severe injury or Disconnect and ground spark plug lead s Before working on engine or equipment disable engine as follows 1 Disconnect spark plug lead s 2 Disconnect negative battery cable from battery External Engine Components A Fixed Guard B Air Cleaner Cover C Debris Screen D Blower Housing E Hose Clamp F Fuel Pump G Hose Clip H Fuel Line Fuel Filter J Oil Filter K Outer Baffle L Electric Starter M Inner Baffle N Ignition Module Intake Manifold P Carburetor Q Gasket R Air Cleaner Base S Paper Element T Rectifier Regulator U Dipstick Tube V Oil Fill Dipstick Breather Hose X Precleaner Y Retractable Starter 48 KohlerEngines com 16 690 01 Rev Clean all parts thoroughly as engine is disassembled Only clean parts can be accurately inspected and gauged for wear or damage There are many commercially available cleaners that will quickly remove grease oil and grime from engine parts When such a cleaner is used follow manufacturer s instructions and safety precautions carefully Make sure all traces of cleaner are removed before engine is reassembled and placed into operation Even small amounts of these cleaners can quickly break down lubricating properties of engine oil Disconnect Spark Plug Leads NOTE Pull on boot only to prevent damage to spark pl
6. 66 KohlerEngines com Valve Cover RTV Sealant A RTV Sealant Valve Cover Torque Sequence NOTE Always use fresh sealant Using outdated sealant can result in leakage Refer to Tools and Aids for information on sealant dispenser NOTE To ensure proper adhesion of sealant to both sealing surfaces perform step 3 immediately 5 minutes maximum after application of RTV RTV silicone sealant is used as a gasket between valve cover and cylinder head Refer to Tools and Aids for a listing of approved sealants 1 Prepare sealing surfaces of cylinder heads and valve covers Flatness of sealing surface must be checked prior to reinstallation See Disassembly 2 Apply a 1 5 mm 1 16 in bead of sealant to valve cover as shown 3 Position covers on cylinder heads If a pulse style fuel pump is used valve cover with pulse fitting hole must be installed on side 2 Install screws in each cover and finger tighten 4 Torque valve cover fasteners to 9 6 N m 85 in Ib using sequence shown 16 690 01 Rev Install Spark Plugs 1 Check gap using wire feeler gauge Adjust gap to 0 76 mm 0 03 in 2 External Engine Components Install plug into cylinder head 3 Torque plug to 27 N m 20 ft Ib Reassembly
7. BATTERY CHARGING SYSTEM NOTE Observe following guidelines to avoid damage to electrical system and components e Make sure battery polarity is correct A negative ground system is used e Disconnect rectifier regulator plug and or wiring harness plug before doing any electric welding on equipment powered by engine Disconnect all other electrical accessories in common ground with engine e Prevent stator AC leads from touching or shorting while engine is running This could damage stator Most engines are equipped with a 12 15 amp regulated charging system Some have a 25 amp regulated charging system 12 15 25 Amp Regulated Charging System Stator Stator is mounted on crankcase behind flywheel Follow procedures in Disassembly and Reassembly if stator replacement is necessary Rectifier Regulator NOTE When installing rectifier regulator take note of terminal positions and install plug correctly NOTE Disconnect all electrical connections attached to rectifier regulator Testing may be performed with rectifier regulator mounted or loose Repeat applicable test procedure 2 or 3 times to determine condition of part Rectifier regulator is mounted on backing shroud assembly To replace it disconnect plug remove mounting screws and ground lead Testing rectifier regulator may be performed as follows using appropriate rectifier regulator tester To test 25 amp rectifier regulators To test 12 15 amp rectifier regulators 1
8. 22 29 in Ib Hook plunger behind upper end of drive lever and install spring into solenoid Insert mounting screws through holes in drive end cap Use these to hold solenoid gasket in position then mount solenoid Torque screws to 4 0 6 0 N m 35 53 in Ib Connect positive 4 brush lead bracket to solenoid and secure with nut Torque nut to 8 11 N m 71 97 in Ib Do not overtighten 16 690 01 Rev KohlerEngines com 41 Starter System Solenoid Tests NOTE DO NOT leave 12 volt test leads connected to solenoid for any time over what is necessary for performing each of individual tests Internal damage to solenoid may occur Disconnect all leads from solenoid including positive brush lead attached to lower stud terminal Remove mounting hardware and separate solenoid from starter for testing To test solenoid pull in coil plunger Actuation 1 Use a 12 volt power supply and 2 test leads 2 Connect 1 lead to flat spade S start terminal on solenoid Momentarily connect other lead to lower large post terminal When connection is made solenoid should energize audible click and plunger retract Repeat test several times Continuity 1 Use an ohmmeter set to audible or Rx2K scale and connect 2 ohmmeter leads to 2 large post terminals 2 Perform solenoid pull in coil plunger actuation test and check for continuity Ohmmeter should indicate continuity Repeat test several times Condition To test sole
9. Carbon Monoxide can cause severe nausea fainting or death Avoid inhaling exhaust fumes A WARNING 5 Rotating Parts can cause severe injury Stay away while engine is in operation Engine exhaust gases contain poisonous carbon monoxide Carbon monoxide is odorless colorless and can cause death if inhaled Keep hands feet hair and clothing away from all moving parts to prevent injury Never operate engine with covers shrouds or guards removed A partial vacuum should be present in crankcase when engine is operating Pressure in crankcase normally caused by a clogged or improperly assembled breather can cause oil to be forced out at oil seals gaskets or other available spots Crankcase vacuum is best measured with either a water manometer or a vacuum gauge Complete instructions are provided in kits To test crankcase vacuum with manometer 1 Insert rubber stopper into oil fill hole Be sure pinch clamp is installed on hose and use tapered adapters to connect hose between stopper and one manometer tube Leave other tube open to atmosphere Check that water level in manometer is at 0 line Make sure pinch clamp is closed 2 Start engine and run no load high speed 3 Open clamp and note water level in tube Level in engine side should be a minimum of 10 2 cm 4 in above level in open side If level in engine side is less than specified low no vacuum or level in en
10. KOHLER Confidant ZT710 ZT740 Service Manual IMPORTANT Read all safety precautions and instructions carefully before operating equipment Refer to operating instruction of eguipment that this engine powers Ensure engine is stopped and level before performing any maintenance or service 2 Safety 3 Maintenance 5 Specifications 13 Tools and Aids 16 Troubleshooting 20 Air Cleaner Intake 21 Fuel System 28 Governor System 29 Lubrication System 31 Electrical System 37 Starter System 45 Emission Compliant Systems 48 Disassembly Inspection and Service 60 Reassembly 16 690 01 Rev Safety SAFETY PRECAUTIONS A WARNING A hazard that could result in death serious injury or substantial property damage A CAUTION A hazard that could result in minor personal injury or property damage NOTE is used to notify people of important installation operation or maintenance information A WARNING Explosive Fuel can cause fires and severe burns LA GA Do not fill fuel tank while engine is hot or running La Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupied buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent WARNING We Accidental Starts can ke cause sev
11. KohlerEngines com 65 Reassembly Adjust Valve Clearance Install Valve Covers Adjusters Retaining Push Rods A Adjuster B Rocker Arm 1 Rotate crankshaft to establish TDC on compression stroke for cylinder 1 Check for a Compression will be felt through spark plug hole b Keyway of crankshaft will be aligned with cylinder 1 c No rocker arm push rod movement if crankshaft is rotated slightly back and forth If they are moving rotate crankshaft 1 full revolution 2 Insert a 0 127 mm 0 005 in feeler gauge between end of 1 valve and rocker arm Turn adjuster until a slight drag is felt Hold in this position and tighten setscrew securely Torque setscrew to 7 9 N m 70 in Ib After tightening recheck adjustment Proper valve clearance is 0 101 0 152 mm 0 004 0 006 in 3 Repeat procedure for other valve on side 1 4 Viewed from PTO end rotate crankshaft 270 3 4 turn counterclockwise and align crankshaft keyway with cylinder 2 which now puts cylinder at TDC on compression stroke 5 Repeat steps 3 4 for setting valve clearance on side 2 6 Rotate crankshaft to check for free operation of valve train Check for clearance between valve spring coils at full lift or bending of push rod s can occur Minimum allowable clearance is 0 25 mm 0 010 in Check Assembly Rotate crankshaft a minimum of 2 revolutions to check longblock assembly and overall proper operation
12. Ch Do not fill fuel tank while engine is hot or running Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupied buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent NOTE E15 E20 and E85 are NOT approved and should NOT be used effects of old stale or contaminated fuel are not warrantable Fuel must meet these requirements e Clean fresh unleaded gasoline e Octane rating of 87 R M 2 or higher e Research Octane Number RON 90 octane minimum e Gasoline up to 10 ethyl alcohol 90 unleaded is acceptable e Methyl Tertiary Butyl Ether MTBE and unleaded gasoline blend max 1596 MTBE by volume are approved e Do not add oil to gasoline e Do not overfill fuel tank e Do not use gasoline older than 30 days KohlerEngines com STORAGE If engine will be out of service for 2 months or more follow procedure below 1 Add Kohler PRO Series fuel treatment or equivalent to fuel tank Run engine 2 3 minutes to get stabilized fuel into fuel system failures due to untreated fuel are not warrantable 2 Change oil while engine is still warm from operation Remove spark plug s and pour about 1 oz of engine oil into cylinder s Replace spark plug s and crank engine slowly to distribute oil 3
13. Clean surfaces with isopropyl alcohol acetone lacquer thinner or electrical contact cleaner Connecting Rods Piston Breather Components Install Breather Filter and Outer Cover Fastener Torque Sequence and Sealant A Piston Ring Set B Piston Pin Retainer C Piston D Piston Pin Connecting Rod E Connecting Rod End Cap Breather G Breather Filter H Cover l Oil Seal Breather Hose Install Flywheel End Oil Seal 1 Make sure seal bore of crankcase is clean and free of any nicks or burrs 2 Apply a light coat of engine oil to outside diameter of oil seal 3 Install oil seal into crankcase using a seal driver Make sure oil seal is installed straight and true in bore and tool bottoms against crankcase 60 1 amp 5 O 3O JO O4 20 0 A Sealant Bead NOTE Always use fresh sealant Using outdated sealant can result in leakage Refer to Tools and Aids for a listing of approved sealants NOTE To ensure proper adhesion of sealant to both sealing surfaces perform step 4 immediately 5 minutes maximum after application of RTV NOTE RTV sealant should be allowed to cure a 1 2 KohlerEngines com minimum of 1 hour before engine is started Install breather filter between 2 ribs inside breather chamber Make sure sealing surfaces are clean and free of nicks or damage Apply a 1 5
14. Connect single lead adapter in between B center 1 Connect tester ground lead with spring clamp to terminal of rectifier regulator being tested and body of rectifier regulator being tested squared single end of tandem adapter lead 2 Connect tester red lead to B terminal of rectifier 2 Connect tester ground lead with spring clamp to regulator and 2 black tester leads to 2 AC terminals body of rectifier regulator 3 Plug tester into proper AC outlet power for tester 3 Connect red lead and 1 black lead to terminals on being used Turn on power switch POWER light open end of tandem adapter lead connections are should be illuminated and 1 of 4 status lights may be not location specific on as well This does not represent condition of part 4 Connect remaining black lead from tester to 1 outer 4 Press TEST button until a click is heard and then AC terminal on rectifier regulator release Momentarily 1 of 4 status lights will 5 Plug tester into proper AC outlet power for tester illuminate indicating condition of part being used Turn on power switch POWER light should be illuminated and 1 of 4 status lights may be on as well This does not represent condition of part 6 Press TEST button until a click is heard and then release Momentarily 1 of 4 lights will illuminate indicating partial condition of part Condition Conclusion 25 amp 12 15 amp OK green light comes on and stays steady Disconnect tester black lead Part is
15. Remove needle clean needle and seat and blow with compressed air Bowl vent or air bleeds plugged Clean vent ports and air bleeds Blow out all passages with compressed air Leaky cracked or damaged float Submerge float to check for leaks Engine runs lean indicated by misfiring loss of speed and power Float level is set too low Adjust float Keihin only Walbro not adjustable governor hunting or excessive throttle opening channels Idle holes plugged dirt in fuel delivery Clean main fuel jet and all passages blow out with compressed air Fuel leaks from carburetor Float level set too high Adjust float Keihin only Walbro not adjustable Dirt under fuel inlet needle Remove needle clean needle and seat and blow with compressed air Bowl vents plugged Blow out with compressed air Carburetor bowl gasket leaks Replace gasket FUEL SYSTEM Fuel Shut off Solenoid Most carburetors are equipped with a fuel shut off solenoid Solenoid is attached to fuel bowl Solenoid has a spring loaded pin that retracts when 12 volts is applied to lead allowing fuel flow to main jet When current is removed pin extends blocking fuel flow Below is a simple test performed with engine off that can determine if solenoid is functioning properly 1 Shut off fuel and remove solenoid from carburetor When solenoid is loosened and removed gas wi
16. lubricant Reinstall or replace drive components assembling them in reverse order they were removed Retaining Ring Installation 1 Position retaining ring in groove in one of inner halves Assemble other half over top and slide on outer collar 2 certain drive components are installed in correct sequence onto armature shaft 3 Slip tool over end of armature shaft so retaining ring inside is resting on end of shaft Hold tool with one hand exerting slight pressure toward starter Tap top of tool with a hammer until you feel retaining ring snap into groove Disassemble and remove tool 4 Squeeze retaining ring with a pliers to compress it into groove 5 Assemble inner halves with larger cavity around spring retainer Slide collar over them and thread center screw in until resistance is felt 6 Hold base of tool with a 1 1 8 wrench and turn center screw clockwise with a 1 2 or 13 mm wrench to draw spring retainer up around retaining ring Stop turning when resistance increases Disassemble and remove tool 7 Reinstall dust cover 16 690 01 Rev Starter Disassembly 1 Remove drive components following instructions for servicing drive 2 Remove thru bolts 3 Remove commutator end cap containing brush holder brushes brush springs and thrust washer cup 4 Remove drive end cap 5 Remove armature from inside starter frame End Cap Brush Replacement Brushes are contained in a p
17. oil control ring first and top compression ring last To install new piston rings proceed as follows 1 Oil control ring bottom groove Install expander and then rails Make sure ends of expander are not overlapped 2 Middle compression ring center groove Install center ring using a piston ring expander tool Make sure identification mark is up or colored dye stripe if contained is to left of end gap 3 Top compression ring top groove Install top ring using a piston ring expander tool Make sure identification mark is up or colored dye stripe if contained is left of end gap Remove Crankshaft Carefully pull crankshaft from crankcase Inspection and Service Inspect gear teeth of crankshaft If teeth are badly worn chipped or some are missing replacement of crankshaft will be necessary Inspect crankshaft bearing surfaces for scoring grooving etc Measure running clearance between crankshaft journals and their respective bearing bores Use an inside micrometer or telescoping gauge to measure inside diameter of both bearing bores in vertical and horizontal planes Use an outside micrometer to measure outside diameter of crankshaft main bearing journals Subtract journal diameters from their respective bore diameters to get running clearances Check results against values in Specifications If running clearances are within specification and there is no evidence of scoring grooving etc no further recon
18. 040 7 060 mm 0 2772 0 2780 in 33 37 33 63 mm 1 3138 1 3240 in 29 37 29 63 mm 1 1563 1 1665 in Valve Face Angle 45 45 Valve Margin Min Valve Stem Diameter IIO n mo OU gt 1 5 mm 0 0591 in 6 982 7 000 mm 0 2749 0 2756 in 1 5 mm 0 0591 in 6 970 6 988 mm 0 2744 0 2751 in After cleaning check flatness of cylinder head and corresponding top surface of crankcase using a surface plate or piece of glass and feeler gauge Maximum allowable out of flatness is 0 076 mm 0 003 in Carefully inspect valve mechanism parts Inspect valve springs and related hardware for excessive wear or distortion Check valves and valve seat area or inserts for evidence of deep pitting cracks or distortion 52 Check clearance of valve stems in guides See valve details and specifications Hard starting or loss of power accompanied by high fuel consumption may be symptoms of faulty valves Although these symptoms could also be attributed to worn rings remove and check valves first After removal clean valve heads faces and stems with a power wire brush Then carefully inspect each valve for defects such as warped head excessive corrosion or worn stem end Replace valves found to be in bad condition KohlerEngines com 16 690 01 Rev Disassembly Inspection and Service Valve Guides If a valve guide is worn beyond specifications it will not guide valve in a straight
19. Aluminum Size Grade 2 Grade 5 Grade 8 Tightening Torque N m Ib 20 8 32 2 3 20 2 8 25 2 3 20 10 24 3 6 32 4 5 40 3 6 32 10 32 3 6 32 4 5 40 1 4 20 7 9 70 13 0 115 18 7 165 7 9 70 1 4 28 9 6 85 15 8 140 22 6 200 5 16 18 17 0 150 28 3 250 39 6 350 17 0 150 5 16 24 18 7 165 30 5 270 3 8 16 29 4 260 3 8 24 33 9 300 Tightening Torque N m ft Ib 20 5 16 24 40 7 30 3 8 16 47 5 35 67 8 50 3 8 24 54 2 40 81 4 60 7 16 14 47 5 35 74 6 55 108 5 80 7 16 20 61 0 45 101 7 75 142 5 105 1 2 13 67 8 50 108 5 80 155 9 115 1 2 20 94 9 70 142 4 105 223 7 165 9 16 12 101 7 75 169 5 125 237 3 175 9 16 18 135 6 100 223 7 165 311 9 230 5 8 11 149 5 110 244 1 180 352 6 260 5 8 18 189 8 140 311 9 230 447 5 330 3 4 10 199 3 147 332 2 245 474 6 350 3 4 16 271 2 200 440 7 325 637 3 470 Metric Fastener Torque Recommendations for Standard Applications Property Class Noncritical Site M i Tightening Torque N m in Ib x 10 M4 1 2 11 1 7 15 2 9 26 4 1 36 5 0 44 2 0 18 M5 2 5 22 3 2 28 5 8 51 8 1 72 9 7 86 4 0 35 M6 4 3 38 5 7 50 9 9 88 14 0 124 16 5 146 6 8 60 M8 10 5 93 13 6 120 24 4 216 33 9 300 40 7 360 17 0 150 Tightening Torque N m ft Ib 10 M10 21 7 16 27 1 2
20. Disconnect negative battery cable 4 Store engine in a clean dry place 16 690 01 Rev Specifications Engine Dimensions with Low Profile Air Cleaner Dimensions in millimeters Inch equivalents shown in EVAP CONNECTION POINT 4X 5 16 18 UNC 28 NO STUDS d ee ah ENS lili Wh 1 97 Biz CABLE MOUNTING SURFACE 308 1 OIL FILL amp SEH 12 13 1350 10 54 FUEL LINE 1055 V 41 00 CONNECTION 15 58 0 41 POINT MOUNTING LE TOP VIEW VET m egene 920 e Eau i TEE TARTER i STUD S POL PORT 1 05 ENGINE MOUNTING 283 MOUNTING SURFACE EXHAUST SURFACE p U mem SE A C DN 4432 17 45 379 6 14 94 OP OF AIR CLEANER 7 e mi SP v Ts Di ENGINE MOUNTING MOUNTING SURFACE HOLE A OIL FILTER SIDE 80 3 3 16 16 690 01 Rev KohlerEngines com Specifications Engine Dimensions with Heavy Duty Air Cleaner Dimensions in millimeters Inch equivalents shown in EVAP CONNECTION POINT 4X 5 16 18 UNC 28 165 NO STUDS i 3129 PORTA 12 28 Dag 10 54 4X 1048 41 00 OIL FILL 0 413 911614 beg Sa FUEL LINE CONNECTION POINT LE A TOP VIEW ENGINE MOUNTING SURFACE PTO END E T x 20 GC e Ji i Si
21. Limit 40 974 40 987 mm 1 6131 1 6137 in 41 000 mm 1 6142 in Bore in oil pan N Max Out of Round ew 40 974 41 000 mm 1 6457 1 6142 in Crankshaft Bore in oil pan to Crankshaft Running Clearance New 0 039 0 087 mm 0 0015 0 0034 in Flywheel End Main Bearing Journal New 40 913 40 935 mm 1 6107 1 6116 in Max Wear Limit 40 840 mm 1 608 in Max Taper 0 022 mm 0 0009 in 0 025 mm 0 0010 in Oil Pan End Main Bearing Journal O D New Max Wear Limit Max Taper Max Out of Round 40 913 40 935 mm 1 6107 1 6116 in 40 840 mm 1 608 in 0 022 mm 0 0009 in 0 025 mm 0 0010 in Connecting Rod Journal New 35 950 35 974 1 4154 1 4163 O D Max Wear Limit 35 950 mm 1 4154 in Max Taper 0 018 mm 0 0007 in Max Out of Round 0 025 mm 0 0010 in T R End Crank in Engine Entire Crank in V Blocks 0 279 mm 0 0110 in 0 200 mm 0 0079 in Cylinder Bore Bore I D New Max Wear Limit Max Out of Round Max Taper 83 006 83 031 mm 3 2679 in 3 2689 in 83 069 mm 3 2704 in 0 120 mm 0 0047 in 0 050 mm 0 0020 in Cylinder Head Max Out of Flatness 0 076 mm 0 003 in Governor Governor Cross Shaft to Crankcase Running Clearance 0 025 0 126 mm 0 0009 0 0049 in Cross Shaft O D New Max Wear Limit 7 949 8 000 mm 0 3129 0 3149 in 7 936 mm 0 3
22. Valve Spring Cap E Valve Stem Seal F Valve Spring G Valve Spring Keeper H Stud Spark Plug J Guide Plate K Push Rod L Rocker Arm M Rocker Arm Pivots N Adjusters Washer P Valve Cover Remove Spark Plugs Remove Cylinder Heads Remove spark plug from each cylinder head Remove Valve Covers and Cylinder Heads NOTE Valve cover is sealed to cylinder head using RTV silicone sealant When removing valve cover use care not to damage gasket surfaces of cover and cylinder head To break RTV seal hold a block of wood against 1 flat face of valve cover Strike wood firmly with a mallet If seal doesn t break loose after 1 or 2 attempts repeat procedure on other side 1 Remove Torx screws securing each valve cover 2 Using abrass wire brush and gasket remover or similar solvent clean old RTV from surface of cylinder head and valve cover 3 Sealing surface of stamped steel valve covers must be checked for flatness prior to reinstallation Hold valve cover down firmly against a flat level surface or piece of glass and check around entire perimeter that a 0 012 in 0 30 mm feeler gauge cannot be inserted anywhere If gauge goes in anywhere cover needs to be replaced 16 690 01 Rev NOTE Exhaust side is located on output shaft side of engine while intake side is located on fan side of engine Cylinder head number is embossed on outside of each cylinder head 1 Loosen inner setscrews T25 TORX
23. angle Cutting proper 45 valve face angle as specified and proper valve seat angle 44 5 half of full 89 angle will achieve desired 0 5 1 0 full cut interference angle where maximum pressure occurs on outside diameters of valve face and seat Lapping Valves NOTE Exhaust valves that are black in color cannot be ground and do not require lapping Reground or new valves must be lapped in to provide fit Use a hand valve grinder with suction cup for final lapping Lightly coat valve face with fine grade of grinding compound then rotate valve on seat with grinder Continue grinding until smooth surface is obtained on seat and on valve face Thoroughly clean cylinder head in soap and hot water to remove all traces of grinding compound After drying cylinder head apply a light coating of SAE 10 oil to prevent rusting Intake Valve Stem Seal Flywheel Ignition Breather Components Always use a new seal when valves are removed A Flywheel Screw B Fan from cylinder head Seals should also be replaced if C Washer D Fan Mounting Plate deteriorated or damaged in any way Never reuse an old seal E Magnet F Flywheel G Stator H Backing Plate Breather Reed Cover J Stud K Retainer L Breather Reed M Flywheel Key N Drive Cup 16 690 01 Rev KohlerEngines com 53 Disassembly Inspection and Service Remove Debris Screen Fan and Flywheel Crank
24. at top dead center TDC of compression stroke Hold engine in this position while testing Holding tool supplied with tester can be used if PTO end of crankshaft is accessible Lock holding tool onto crankshaft Install a 3 8 in breaker bar into hole slot of holding tool so it is perpendicular to both holding tool and crankshaft PTO If flywheel end is more accessible use a breaker bar and socket on flywheel nut screw to hold it in position An assistant may be needed to hold breaker bar during testing If engine is mounted in a piece of equipment it may be possible to hold it by clamping or wedging a driven component Just be certain that engine cannot rotate off of TDC in either direction 4 Install adapter into spark plug hole but do not attach it to tester at this time 5 Turn regulator knob completely counterclockwise 6 Connect an air source of at least 50 psi to tester 7 Turn regulator knob clockwise increase direction until gauge needle is in yellow set area at low end of scale 8 Connect tester quick connect to adapter hose While firmly holding engine at TDC gradually open tester valve Note gauge reading and listen for escaping air at combustion air intake exhaust outlet and crankcase breather Condition Conclusion Air escaping from crankcase breather Ring or cylinder worn Air escaping from exhaust system Defective exhaust valve improper seating Air escaping from intake Defective intake valve imp
25. fuel tank is filled with clean fresh gasoline Make sure fuel tank cap vent is not blocked and is G A Idle Speed Screw B Carburetor Body C Idle Jet D Plug E Main Jet F Float Shut off Solenoid G Assembly H Fuel Bowl Choke Lever 22 KohlerEngines com operating properly 3 Make sure fuel is reaching carburetor This includes checking fuel shut off valve fuel tank filter screen in line fuel filter fuel lines and fuel pump for restrictions or faulty components as necessary 4 Make sure air cleaner base and carburetor are securely fastened to engine using gaskets in good condition 5 Make sure air cleaner element including precleaner if equipped is clean and all air cleaner components are fastened securely 6 Make sure ignition system governor system exhaust system and throttle and choke controls are operating properly 16 690 01 Rev Troubleshooting Carburetor Related Causes Fuel System Condition Possible Cause Conclusion Engine runs rich indicated by black Clogged air cleaner Clean or replace air cleaner sooty exhaust smoke misfiring loss of speed and power governor operation Choke partially closed during Check choke lever linkage to ensure choke is operating properly hunting or excessive throttle opening Float level is set too high Adjust float Keihin only Walbro not adjustable Dirt under fuel inlet needle
26. good and may be used attached to 1 AC terminal and reconnect it to other AC terminal Repeat test If OK green light comes on again part is good and may be used NOTE A flashing LOW light can also occur as Rectifier regulator is faulty and should not be used a result of an inadequate ground lead connection Make certain connection location is clean and clamp is secure Other lights come on 16 690 01 Rev KohlerEngines com 35 Electrical System 12 15 25 Amp Battery Charging Systems NOTE Always zero ohmmeter on each scale before testing to ensure accurate readings Voltage tests should be made with engine running at 3600 RPM with no load Battery must be good and fully charged When problems occur in keeping battery charged or battery charges at high rate charging system or battery might be causing problems To test charging system for no charge to battery 1 Insert an ammeter in B lead from rectifier regulator With engine running at 3600 RPM and B at terminal on rectifier regulator to ground using a DC voltmeter If voltage is 13 8 volts or more place a minimum load of 5 amps turn on lights if 60 watts or more or place a 2 5 ohm 100 watt resistor across battery terminals on battery to reduce voltage Observe ammeter Conclusion Charging system is OK and battery was fully charged Test stator and rectifier regulator steps 2 and 3 Condition Charge rate increases
27. gravity of battery If low recharge or replace slowly battery as necessary Brushes Check for excessively dirty or worn brushes and commutator Clean using a coarse cloth not emery cloth Replace brushes if excessively or unevenly worn Transmission Make sure clutch or transmission is disengaged or placed or Engine in neutral This is especially important on equipment with hydrostatic drive Transmission must be exactly in neutral to prevent resistance which could keep engine from starting Check for seized engine components such as bearings connecting rod and piston 16 690 01 Rev KohlerEngines com 37 Starter System INERTIA DRIVE ELECTRIC STARTERS Inertia Drive Electric Starter Components BD A End Cap Frame C Armature D Drive End Cap E Drive Nut Collar F Drive Pinion G Anti Drift Spring H Spring Retainer I Retaining Ring J Dust Cover When power is applied to starter armature rotates As armature rotates drive pinion moves out on drive shaft splines and into mesh with flywheel ring gear When pinion reaches end of drive shaft it rotates flywheel and cranks engine When engine starts flywheel rotates faster than starter armature and drive pinion This moves drive pinion out of mesh with ring gear and into retracted position When power is removed from starter armature stops rotating and drive pinion is held in retracted position by anti drift
28. in Ib Install Oil Filter and Fill Crankcase with Oil NOTE Make sure oil drain plug is installed and torqued to specification to prevent oil leakage 1 Install oil drain plug Torque plug to 13 6 N m 10 ft Ib 2 Place new filter in shallow pan with open end up Fill with new oil until oil reaches bottom of threads Allow 2 minutes for oil to be absorbed by filter material 3 Apply a thin film of clean oil to rubber gasket on new filter 4 Refer to instructions on oil filter for proper installation 5 Fill crankcase with new oil Level should be at top of indicator on dipstick 6 Reinstall oil fill dipstick and tighten securely 16 690 01 Rev Reassembly Connect Spark Plug Leads Connect leads to spark plugs Prepare Engine for Operation Engine is now completely reassembled Before starting or operating engine be sure to do following 1 Make sure all hardware is tightened securely 2 Make sure oil drain plug Oil Sentry pressure switch and a new oil filter are installed 3 Adjust carburetor idle soeed adjusting screw as necessary Testing Engine It is recommended engine be operated on a stand or bench prior to installation in piece of equipment 1 Run engine at idle for 2 3 minutes then 5 6 minutes more between idle and midrange 2 Adjust idle soeed screw and high speed stop as necessary Make sure maximum engine speed does not exceed 3750 RPM no load 16 69
29. line This may result in burnt valve faces or seats loss of compression and excessive oil consumption To check valve guide to valve stem clearance thoroughly clean valve guide and using a split ball gauge measure inside diameter of guide Then using an outside micrometer measure diameter of valve stem at several points on stem where it moves in valve guide Use largest stem diameter to calculate clearance by subtracting stem diameter from guide diameter If intake clearance exceeds 0 040 0 078 mm 0 0016 0 0031 in or exhaust clearance exceeds 0 052 0 090 mm 0 0020 0 0035 in determine whether valve stem or guide is responsible for excessive clearance Maximum I D wear on intake valve guide is 7 140 mm 0 2811 in while 7 160 mm 0 2819 in is maximum allowed on exhaust guide Guides are not removable but can be reamed 0 25 mm 0 010 in oversize Valves with 0 25 mm oversize stems must then be used If guides are within limits but valve stems are worn beyond limits install new valves Valve Seat Inserts Hardened steel alloy intake and exhaust valve seat inserts are press fitted into cylinder head Inserts are not replaceable but can be reconditioned if not too badly pitted or distorted If cracked or badly warped cylinder head should be replaced Recondition valve seat inserts following instructions provided with valve seat cutter being used Final cut should be made with an 89 cutter as specified for valve seat
30. mm 1 16 in bead of RTV sealant to sealing surface of breather cover See sealant pattern Immediately install cover onto crankcase Do not allow RTV sealant to come into contact with any other components Secure breather cover with M5 screws Torque screws in sequence shown to 8 5 N m 75 in Ib into a new cored hole or 4 0 N m 35 in Ib into a used hole Attach breather hose if disconnected earlier 16 690 01 Rev Crankshaft Governor Gear Oil Pump Components Reassembly Install Governor Cross Shaft Governor Cross A Shaft B Crankshaft C Valve Tappets D Camshaft E Regulating Pin F Shaft Locking Tab Thrust G Governor Gear H Washer Oil Pan J Drain Plug K Oil Seal L Oil Pump M Oil Sentryy N Ball O Spring P Oil Pick up Screen EE R Outer Gerotor Gear 16 690 01 Rev 1 Lubricate governor cross shaft bearing surfaces in crankcase with engine oil 2 Slide lower washer onto governor cross shaft and install cross shaft from inside of crankcase 3 Install nylon washer onto governor cross shaft then start push on retaining ring Hold cross shaft up in position place a 0 50 mm 0 020 in feeler gauge on top of nylon washer and push retaining ring down shaft to secure Remove feeler gauge which will have established proper endplay Install Crankshaft 1 Lubricate flywheel side main bearing surface and lips
31. move throttle choke control from fast choke ON position and set desired engine operating speed between slow and fast position 16 690 01 Rev KohlerEngines com Fuel System 27 Governor System GOVERNOR Governed speed setting is determined by position of throttle control It can be variable or constant depending on engine application Governor is designed to hold engine speed constant under changing load conditions Most engines are equipped with a centrifugal flyweight mechanical governor Governor gear flyweight mechanism of mechanical governor is mounted inside oil pan and is driven off gear on camshaft Governor Components e 5 T we Inside Engine a UN M J A Throttle Lever B Throttle Linkage C Nut D Governor Lever E Governor Spring F Choke Linkage G Cross Shaft H Flyweight Regulating Pin J Governor Gear K E L Shaft This governor design works as follows Governor Adjustments e Centrifugal force acting on rotating governor gear assembly causes flyweights to move outward as speed increases Governor spring tension moves them inward as speed decreases to move outward Regulating pin contacts tab on cross shaft causing shaft to rotate One end of cross shaft protrudes through crankcase Rotating action of cross shaft is transmitted to throttle lever of carburetor through external throttle linkage When engine
32. of oil seal in crankcase with clean engine oil 2 Carefully slide flywheel end of crankshaft through main bearing in crankcase Install Connecting Rods with Pistons and Rings Piston and Connecting Rod Details A Side 1 B Side 2 NOTE Oylinders are numbered on crankcase Make sure to install piston connecting rod and end cap into its appropriate cylinder bore as previously marked during disassembly Do not mix end caps and connecting rods NOTE Proper orientation of piston connecting rod assemblies inside engine is extremely important Improper orientation can cause extensive wear or damage Be certain pistons and connecting rods are assembled exactly as shown NOTE Align chamfer of connecting rod with chamfer of its mating end cap When installed flat faces of connecting rods should face each other Faces with raised rib should be toward outside 1 Stagger piston rings in grooves until end gaps are 120 apart Oil ring rails should also be staggered 2 Lubricate cylinder bore piston and piston rings with engine oil Compress rings using a piston ring compressor 3 Lubricate crankshaft journals and connecting rod bearing surfaces with engine oil KohlerEngines com 61 Reassembly 4 Make sure FLY stamping on piston is facing toward flywheel side of engine Use a hammer with a rubber or wood grip and gently tap piston into cylinder Be careful oil ring rails do not spring free between bo
33. pan If service is required continue following steps Inspection Inspect governor gear teeth Replace gear if it is worn chipped or if any teeth are missing Inspect governor weights They should move freely in governor gear Disassembly Governor Shaft Component and Details A 940 mm 1 3386 in 33 5 mm 1 3189 in 19 40 mm 0 7638 in C Gear Shaft NOTE Governor gear is held onto shaft by small molded tabs in gear When gear is removed from shaft these tabs are destroyed and gear must be replaced Therefore remove gear only if absolutely necessary Governor gear must be replaced once it is removed from oil pan 1 Use 2 small screwdrivers and carefully pry upward to remove regulating pin and governor gear assembly 2 Remove locking tab thrust washer located under governor assembly 16 690 01 Rev Disassembly Inspection and Service 3 Carefully inspect governor gear shaft and replace it only if it is damaged After removing damaged shaft press or lightly tap replacement shaft into oil pan to depth shown Reassembly 1 Install locking tab thrust washer on governor gear shaft with tab down 2 Position regulating pin within governor gear flyweights assembly and slide both onto governor shaft until assembly locks into place Oil Pump Assembly Oil pump is mounted inside oil pan If service is required continue with Disassembly Inspection and Reassembly
34. shim 2 Remove valve tappets from crankcase and mark them by their location as either intake or exhaust and cylinder 1 or 2 Tappets should always be reinstalled in same position Camshaft Inspection and Service Check lobes of camshaft for wear or damage See Specifications for minimum lift specifications Inspect cam gear for badly worn chipped or missing teeth Replacement of camshaft will be necessary if any of these conditions exist Valve Tappets Inspection Check base surface of valve tappet s for wear or damage Replace tappet s if condition is questionable in any way Corresponding camshaft lobe s should also be checked for wear or damage Whenever tappets are replaced apply a liberal coating of Kohler lubricant to base of each new tappet before it is installed Remove Governor Cross Shaft Governor Cross Shaft Oil Seal Details Piston Pin Retainer Piston Pin A Piston Ring Set B C Piston D Connecting Rod End Cap Breather Cover E Connecting Rod G Breather Filter H Governor Cross A 2 0 mm 0 0787 in B Shaft Seal 1 Remove retainer and washer from governor cross shaft 2 Remove cross shaft with small inner washer through inside of crankcase 3 Remove governor shaft seal from crankcase If governor cross shaft seal is damaged and or leaks replace it using following procedure Remove oil seal from cra
35. surface of oil pan See sealant pattern Oil pan must be installed within 5 minutes of sealant being applied for proper sealing to occur Make sure end of governor cross shaft is lying against bottom of cylinder inside crankcase Install oil pan to crankcase Carefully seat camshaft with shim and crankshaft into their mating bearings Rotate crankshaft to help engage oil pump and governor gear meshes Install 10 screws securing oil pan to crankcase Torque fasteners in sequence shown to 24 4 N m 216 in Ib San EL m A Flywheel Screw B Fan C Washer D Fan Mounting Plate E Magnet F Flywheel G Stator H Backing Plate Breather Reed Cover J Stud K Retainer L Breather Reed M Flywheel Key N Drive Cup KohlerEngines com 63 Reassembly Install Breather Reed and Outer Cover Install Flywheel and Fan Breather Cover Sealant A Sealant Bead NOTE RTV sealant should be allowed to cure a 1 minimum of 1 hour before engine is started Install breather reed followed by retainer over passage hole and mounting hole in crankcase Hold in position and secure with mounting stud Torque stud to 6 2 N m 55 in Ib into a new cored hole or 4 0 N m 35 in Ib into a used hole Invert breather reed cover and apply a 1 5 mm 1 16 in bead o
36. when load is applied Charge rate does not increase when load is applied 2 Remove connector from rectifier regulator With engine running at 3600 RPM measure AC voltage across stator leads using an AC voltmeter Condition Conclusion Voltage is 28 volts or Stator is OK Rectifier more regulator is faulty replace Stator is faulty replace Test stator further using an ohmmeter steps 3 and 4 Voltage is less than 28 volts To test charging system for battery continuously charging at high rate 1 With engine running at 3600 RPM measure voltage from B lead to ground using a DC voltmeter Condition Conclusion 3 With engine stopped measure resistance across stator leads using an ohmmeter Condition Conclusion Resistance is 0 064 0 2 Stator is OK ohms Resistance is 0 ohms Stator is shorted replace Resistance is infinity Stator is open replace ohms 4 With engine stopped measure resistance from each stator lead to ground using an ohmmeter Condition Conclusion Resistance is infinity ohms no continuity Stator is OK not shorted to ground Resistance or continuity measured Stator leads are shorted to ground replace 36 KohlerEngines com Charging system is OK Battery is unable to hold charge service or replace Voltage is 14 7 volts or less Voltage is more than 14 7 Faulty rectifie
37. 0 47 5 35 66 4 49 81 4 60 33 9 25 M12 36 6 27 47 5 35 82 7 61 116 6 86 139 7 103 61 0 45 M14 58 3 43 76 4 56 131 5 97 184 4 136 219 7 162 94 9 70 Torque Conversions N m in Ib x 0 113 N m ft Ib x 1 356 in Ib N m x 8 85 ft Ib Nem x 0 737 12 KohlerEngines com 16 690 01 Rev Certain quality tools are designed to help you perform specific disassembly repair and reassembly procedures By Tools and Aids using these tools you can properly service engines easier faster and safer In addition you ll increase your service capabilities and customer satisfaction by decreasing engine downtime Here is a list of tools and their source SEPARATE TOOL SUPPLIERS Kohler Tools SE Tools Contact your local Kohler source of 415 Howard St supply Lapeer MI 48446 Phone 810 664 2981 Toll Free 800 664 2981 Fax 810 664 8181 TOOLS Description Design Technology Inc 768 Burr Oak Drive Westmont IL 60559 Phone 630 920 1300 Fax 630 920 0011 Source Part No Alcohol Content Tester For testing alcohol content in reformulated oxygenated fuels Kohler 25 455 11 S Camshaft Endplay Plate For checking camshaft endplay SE Tools KLR 82405 Camshaft Seal Protector Aegis For protecting seal during camshaft installation SE Tools KLR 82417 Cylinder Leakdown Tester Individual component available Adapter 12 mm x 14 mm Required
38. 0 01 Rev KohlerEngines com 71 1P16 690 01 2013 by Kohler Co All rights reserved n 85612 72 KohlerEngines com 16 690 01 Rev
39. 124 in Governor Gear Shaft to Governor Running Clearance 0 050 0 210 mm 0 0020 0 0083 in Gear Shaft O D New Max Wear Limit 5 990 6 000 mm 0 2358 0 2362 in 5 977 mm 0 2353 in Ignition Spark Plug Gap 0 76 mm 0 030 in Module Air Gap 0 203 0 305 mm 0 008 0 012 in Values are in Metric units Values in parentheses are English equivalents 10 KohlerEngines com 16 690 01 Rev CLEARANCE SPECIFICATIONS Specifications ZT710 ZT720 ZT730 ZT740 Piston Piston Rings and Piston Pin Piston to Piston Pin Running Clearance 0 006 0 017 mm 0 0002 0 0007 in Max Wear Limit Pin Bore I D New 17 006 17 012 mm 0 6695 0 6698 in Max Wear Limit 17 025 mm 0 6703 in Pin O D New 16 995 17 000 mm 0 6691 0 6693 in 16 994 mm 0 6691 in Top Compression Ring to Groove Side Clearance 0 030 0 070 mm 0 0010 0 0026 in Middle Compression Ring to Groove Side Clearance 0 030 0 070 mm 0 0010 0 0026 in Oil Control Ring to Groove Side Clearance 0 060 0 190 mm 0 0022 0 0073 in Top Compression Ring End Gap New Bore Used Bore Max Center Compression Ring End Gap New Bore Used Bore Max 0 189 0 277 mm 0 0074 0 0109 in 0 531 mm 0 0209 in 1 519 1 797 mm 0 0598 0 0708 in 2 051 mm 0 0808 in Thrust Face O D New Max Wear Limit 82 978 mm 3 2668 in 82 833 mm 3 2611 in Piston Thrust Face to
40. Cylinder Bore Running Clearance New 0 019 0 062 mm 0 0007 0 0024 in Valves and Valve Tappets Clearance 0 127 0 178 mm 0 0050 0 0070 in Valve Tappet to Crankcase Running Clearance 0 013 0 073 mm 0 0005 0 0029 in Intake Valve Stem to Valve Guide Running Clearance 0 040 0 0780 mm 0 0016 0 0031 in Exhaust Valve Stem to Valve Guide Running Clearance 0 052 0 090 mm 0 0020 0 0035 in Intake Valve Guide New Max Wear Limit 7 040 7 060 mm 0 2772 0 2780 in 7 140 mm 0 2811 in Exhaust Valve Guide New Max Wear Limit 7 040 7 060 mm 0 2772 0 2780 in 7 160 mm 0 2819 in Valve Guide Reamer Size Standard 0 25 mm O S 7 050 mm 0 2776 in 7 300 mm 0 2874 in Intake Valve Minimum Lift Exhaust Valve Minimum Lift 8 500 0 3346 8 500 0 3346 Nominal Valve Face Angle 45 3Values are in Metric units Values in parentheses are English equivalents 7 Measure 6 mm 0 2362 in above bottom of piston skirt at right angles to piston pin 16 690 01 Rev KohlerEngines com Specifications GENERAL TORQUE VALUES English Fastener Torque Recommendations for Standard Applications Bolts Screws Nuts and Fasteners Assembled Into Cast Iron or Steel G rade 2 or 5 Fasteners O ES Into
41. Disassembly 1 Remove screws 2 Lift oil pump assembly from oil pan Remove outer gerotor gear from oil pan 3 Ensure ball and spring remain installed in pressure relief hole of oil pan If ball and spring fall out of pressure relief hole see reassembly for correct installation Inspection Inspect oil pump housing gear and rotors for nicks burrs wear or any visible damage If any parts are worn or damaged replace oil pump assembly Check oil pickup screen for damage or restriction replace if necessary Disassembly of oil pump is not recommended Reassembly 1 Lubricate outer gerotor gear with oil Install outer gerotor gear through shaft of oil pump around inner gerotor gear Matching molding dots on inner and outer gerotor gears is not necessary and will not affect oil pump efficiency 2 Reinstall ball then spring into pressure relief hole of oil pan 3 Install oil pump inserting center shaft into corresponding recess in oil pan Secure oil pump by torquing screws in no specific sequence to 9 9 N m 88 in Ib 4 After torquing rotate gear and check for freedom of movement Make sure there is no binding If binding occurs loosen screws reposition pump retorque screws and recheck movement KohlerEngines com 55 Disassembly Inspection and Service Remove Camshaft and Valve Tappets Connecting Rods Piston Breather Components 1 Position crankcase so flywheel side is down Remove camshaft and
42. Ib Solenoid Shift 5 6 9 0 N m 49 79 in lb Mounting Screw 23 8 N m 211 in Ib Brush Holder Mounting Screw 2 5 3 3 N m 22 29 in Ib Stator Mounting Screw 8 8 N m 78 in Ib Valve Cover Fastener 9 6 N m 85 in Ib CLEARANCE SPECIFICATIONS ZT710 ZT720 ZT730 ZT740 Camshaft End Play 0 06 0 40 mm 0 0024 0 0157 in Running Clearance 0 040 0 077 mm 0 0016 0 0030 in Bore New 20 000 20 025 mm 0 7874 0 7884 in Max Wear Limit 20 038 mm 0 7889 in Bearing Surface O D New 19 948 19 960 mm 0 7854 0 7858 in Max Wear Limit 19 945 mm 0 7852 in Connecting Rod Connecting Rod to Crankpin Running Clearance New 0 037 0 083 mm 0 0015 0 0033 in Max Wear Limit 0 098 mm 0 0039 in Connecting Rod to Crankpin Side Clearance 0 261 0 67 mm 0 0102 0 0264 in Connecting Rod to Piston Pin Running Clearance 0 013 0 032 mm 0 0005 0 0013 in Piston Pin End I D New 17 013 17 027 mm 0 6698 0 6704 in Max Wear Limit 17 040 mm 0 6709 in Crankcase Governor Cross Shaft Bore I D New 8 025 8 075 mm 0 3159 0 3179 in Max Wear Limit 8 088 mm 0 3184 in Values are in Metric units Values in parentheses are English equivalents 5 Lubricate threads with engine oil prior to assembly 16 690 01 Rev KohlerEngines com 9 Specifications CLEARANCE SPECIFICATIONS ZT710 ZT720 ZT730 ZT740 Crankshaft End Play free 0 075 0 595 mm 0 0030 0 0023 in Bore in crankcase New Max Wear
43. OTE Main and slow jets are fixed and size specific and can be removed if reguired Fixed jets for high altitudes are available e Inspect carburetor body for cracks holes and other wear or damage e Inspect float for cracks holes and missing or damaged float tabs Check float hinge and shaft for wear or damage e Inspect fuel inlet needle and seat for wear or damage e Inspect spring loaded choke plate to make sure it moves freely on shaft 24 KohlerEngines com NOTE Inlet needle center pin is spring loaded Make sure float assembly rests against fuel inlet needle without depressing center pin 1 Perform removal procedures for appropriate air cleaner and carburetor outlined in Disassembly 2 Clean exterior surfaces of dirt or foreign material before disassembling carburetor Remove bowl retaining screws or solenoid assembly and carefully separate fuel bowl from carburetor Do not damage fuel bowl O rings Transfer any remaining fuel into an approved container Save all parts 3 Remove float pin some carburetors may have a screw which requires removal and inlet needle Seat for inlet needle is not serviceable and should not be removed 4 Remove two screws securing top cover gasket and ground lead Keihin carburetors only Discard gasket and screws only 5 Remove idle speed adjusting screw and spring from carburetor Discard parts 6 Clean carburetor bowl and inlet seat areas as required 7 Carefu
44. OTING GUIDE When troubles occur be sure to check simple causes which at first may seem too obvious to be considered For example a starting problem could be caused by an empty fuel tank Some general common causes of engine troubles are listed below and vary by engine specification Use these to locate causing factors Engine Cranks But Will Not Start Engine Will Not Crank e Battery connected backwards e Blown fuse e Carburetor solenoid malfunction e Choke not closing Clogged fuel line or fuel filter Diode in wiring harness failed in open circuit mode DSAI or DSAM malfunction Empty fuel tank Faulty ignition coil s Faulty spark plug s Fuel pump malfunction vacuum hose clogged or leaking Fuel shut off valve closed Ignition module s faulty or improperly gapped Insufficient voltage to electronic control unit Interlock switch is engaged or faulty e Key switch or kill switch in OFF position e Low oil level e Quality of fuel dirt water stale mixture e SMART SPARK malfunction e Spark plug lead s disconnected Engine Starts But Does Not Keep Running e Battery is discharged e Faulty electric starter or solenoid e Faulty key switch or ignition switch e Interlock switch is engaged or faulty e Loose wires or connections that intermittently ground ignition kill circuit e Pawls not engaging in drive cup e Seized internal engine components Engine Runs But Misses
45. On stationary or unattended applications pumps generators etc pressure switch can be used to ground ignition module to stop engine On vehicular applications lawn tractors mowers etc pressure switch can only be used to activate a low oil warning light or signal 30 KohlerEngines com Installation 1 Apply pipe sealant with Teflon Loctite PST 592 Thread Sealant or equivalent to threads of switch 2 Install switch into tapped hole in oil filter adapter 3 Torque switch to 4 5 N m 40 in Ib Testing Compressed air a pressure regulator pressure gauge and a continuity tester are required to test switch 1 Connect continuity tester across blade terminal and metal case of switch With 0 psi pressure applied to switch tester should indicate continuity switch closed 2 Gradually increase pressure to switch As pressure increases through range of 2 5 psi tester should indicate a change to no continuity switch open Switch should remain open as pressure is increased to 90 psi maximum 3 Gradually decrease pressure through range of 2 5 psi Tester should indicate a change to continuity switch closed down to 0 psi 4 Replace switch if it does not operate as specified 16 690 01 Rev SPARK PLUGS Electrical System Inspection A CAUTION E Electrical Shock can cause injury Do not touch wires while engine is running Spark Plug Component and Details
46. SAI Hose To Carburetor Inlet Screen Operation Maintenance Intake pulse of engine activates secondary air valve Air inlet screen in secondary air valve can be removed Air is drawn through an inlet screen of secondary air cleaned and reinstalled If inspection of system reveals valve Air is then drawn into exhaust manifold and any damage or decomposition of hoses secondary air muffler where it mixes with any unburned hydrocarbons valve or exhaust system parts should be replaced which then burn in heat of muffler A hose is connected between a carburetor port and a diaphragm chamber in secondary air valve Carburetor vacuum moves diaphragm to close valve when air induction is not required primary idle 46 KohlerEngines com 16 690 01 Rev Remove Inlet Screen Emission Compliant Systems Inlet Components A Secondary Air Valve Assembly B Barb C Inlet Screen 1 Remove inlet screen from secondary air valve assembly by grasping inlet screen at base and gently pulling away from valve assembly 2 Use a soft brush to remove debris from screen Run water through inlet screen in reverse direction 4 Toreinstall push inlet screen onto barb of secondary air valve assembly An audible click will be heard when inlet screen is properly reinstalled e 16 690 01 Rev KohlerEngines com 47 Disassembly Inspection and Service xf Nez A WARNING death
47. and back off adjusters 2 Mark location of push rods as either intake or exhaust and cylinder 1 or 2 Push rods should always be installed in same positions 3 Remove screws securing each cylinder head Discard screws once removed Do not reuse 4 Remove cylinder head and head gasket Disassemble Cylinder Heads NOTE Use a new valve stem seal whenever valve is removed or if valve stem seal is deteriorated or damaged Never reuse an old valve stem seal 1 Remove adjusters pivots rocker arms studs and guide plate from cylinder head 2 Compress valve springs using a valve spring compressor KohlerEngines com 51 Disassembly Inspection and Service 3 Once valve spring is compressed remove following 4 items e Valve spring keepers e Valve spring caps e Valve springs Repeat above procedure for other cylinder head Do not interchange parts from 1 cylinder head to another e Intake and exhaust valves mark position e Valve stem seal e Washer intake valve only Inspection and Service Valve Details Exhaust Valve Exhaust Insert 5 N a ae SS SW Intake Insert Intake Valve Valve Head Diameter Dimension Intake Exhaust Seat Angle 89 89 Insert O D 36 987 37 013 mm 1 4562 1 4572 in 32 987 33 013 mm 1 2987 1 2997 in Guide Depth 4 mm 0 1575 in 6 5 mm 0 2559 in Guide I D 7 040 7 060 mm 0 2772 0 2780 in 7
48. anied by excessive gap erosion Lean carburetor settings an intake air leak or incorrect spark timing are normal causes for high combustion temperatures BATTERY A 12 volt battery with 400 cold cranking amps cca is generally recommended for starting in all conditions A smaller capacity battery is often sufficient if an application is started only in warmer temperatures Refer to following table for minimum capacities based on anticipated ambient temperatures Actual cold cranking requirement depends on engine size application and starting temperatures Cranking requirements increase as temperatures decrease and battery capacity shrinks Refer to equipment s operating instructions for specific battery requirements Battery Size Recommendations Temperature Battery Required Above 32 F 0 C 200 cca minimum O F to 32 F 18 C to 0 C 250 cca minimum 5 F to OF 21 C to 18 C 300 cca minimum 10 F 23 C or below 400 cca minimum If battery charge is insufficient to turn over engine recharge battery 32 KohlerEngines com 16 690 01 Rev Electrical System Ignition System These systems use a capacitive discharge CD coil With CDI fixed timing ignition timing and spark remains constant regardless of engine speed Timing of spark is controlled by location of flywheel magnet group as referenced to engine TDC MDI adjustable timing uses a digital microprocessor which is located i
49. are approved for use Loctite Nos 5900 or 5910 are recommended for best sealing characteristics Kohler 25 597 07 S Loctite 59109 Loctite Ultra Black 598 Loctite Ultra Blue 587 Loctite Ultra Copper 5920 Spline Drive Lubricant Kohler 25 357 12 S 14 KohlerEngines com 16 690 01 Rev Tools and Aids FLYWHEEL HOLDING TOOL ROCKER ARM CRANKSHAFT TOOL A flywheel holding tool can be made out of an old junk A spanner wrench to lift rocker arms or turn crankshaft flywheel ring gear and used in place of a strap wrench may be made out of an old junk connecting rod 1 Using an abrasive cut off wheel cut out a six tooth 1 Find a used connecting rod from a 10 HP or larger segment of ring gear as shown engine Remove and discard rod cap 2 Grind off any burrs or sharp edges 2 Remove studs of a Posi Lock rod or grind off 3 Invert segment and place it between ignition bosses SS steps of a Command rod so joint surface is on crankcase so tool teeth engage flywheel ring al gear teeth Bosses will lock tool and flywheel in 3 Finda 1 in long capscrew with correct thread size to position for loosening tightening or removing with a match threads in connecting rod puller 4 Use a flat washer with correct LD to slip on capscrew and approximately 1 in O D Assemble capscrew and washer to joint surface of rod 16 690 01 Rev KohlerEngines com 15 Troubleshooting TROUBLESHO
50. armature shaft 2 Install and assemble stop collar retainer assembly a Install stop collar down onto armature shaft with counter bore recess up b Install a new retainer in larger rear groove of armature shaft Squeeze with a pliers to compress it in groove c Slide stop collar up and lock it into place so recess surrounds retainer in groove If necessary rotate pinion outward on armature splines against retainer to help seat collar around retainer 3 Install offset thrust stop washer so smaller offset of washer faces retainer collar 4 Apply asmall amount of oil to bearing in drive end cap and install armature with drive pinion 5 Lubricate fork end and center pivot of drive lever with drive lubricant Position fork end into space between captured washer and rear of pinion 6 Slide armature into drive end cap and at same time seat drive lever into housing 7 Install rubber grommet into matching recess of drive end cap Molded recesses in grommet should be out matching and aligned with those in end cap 8 Install frame with small notch forward onto armature and drive end cap Align notch with corresponding section in rubber grommet Install drain tube in rear cutout if it was removed previously 9 Install flat thrust washer onto commutator end of armature shaft 10 11 12 13 14 Starter System Starter reassembly when replacing brushes brush holder assembly a Hold starter
51. assembly vertically on end housing and carefully position assembled brush holder assembly with supplied protective tube against end of commutator armature Mounting screw holes in metal clips must be up out Slide brush holder assembly down into place around commutator and install positive brush lead grommet in cutout of frame Protective tube may be saved and used for future servicing Starter reassembly when not replacing brushes brush holder assembly a Carefully unhook retaining caps from brush assemblies Do not lose springs b Position brushes back in their slots so they are flush with I D of brush holder assembly Insert brush installation tool with extension or use tube described above from a prior brush installation through brush holder assembly so holes in metal mounting clips are up out c Install brush springs and snap on retainer caps d Hold starter assembly vertically on end housing and carefully place tool with extension and assembled original brush holder assembly onto end of armature shaft Slide brush holder assembly down into place around commutator install positive brush lead grommet in cutout of frame Install end cap onto armature and frame aligning thin raised rib in end cap with corresponding slot in grommet of positive brush lead Install thru bolts and brush holder mounting screws Torque bolts to 5 6 9 0 N m 49 79 in Ib and brush holder mounting screws to 2 5 3 3 N m
52. ately 1450 RPM Check speed using a tachometer Turn adjustment screw inner clockwise in to increase or counterclockwise out to decrease speed 2 Release governor lever and check that throttle lever is in idle position Obtain equipment manufacturer s recommended idle speed 1750 RPM All engines have a bendable tab that is used to set this speed A pliers should be used to bend this tab to achieve recommended speed Governed idle speed RPM is 300 RPM approximate higher than low idle speed 3 Move throttle lever to wide open full throttle position and hold in this position Turn high speed screw to obtain intended high speed no load RPM Governed idle speed must be set before making this adjustment High Speed RPM Adjustment 1 With engine running move throttle control to fast 2 Turn inner adjustment screw outward to decrease or inward to increase RPM speed Carburetor Servicing We O au QE D HO 1 ER A 12 mm 0 472 in A WARNING ke Accidental Starts can cause severe injury or death K Disconnect and ground spark plug lead s before servicing Before working on engine or equipment disable engine as follows 1 Disconnect spark plug lead s 2 Disconnect negative battery cable from battery N
53. b M4 HI LO Screw M5 Thread Forming Fasteners 2 8 N m 25 in lb 3 4 N m 30 in Ib Carburetor Mounting Nut 6 2 7 3 N m 55 65 in Ib Connecting Rod Cap Fastener torque in increments 11 3 N m 100 in lb 3Values are in Metric units Values in parentheses are English equivalents 4 Exceeding maximum angle of operation may cause engine damage from insufficient lubrication 5 Lubricate threads with engine oil prior to assembly Any and all horsepower hp references by Kohler are Certified Power Ratings and per SAE J1940 8 J1995 hp standards Details on Certified Power Ratings can be found at KohlerEngines com 16 690 01 Rev KohlerEngines com Specifications TORQUE SPECIFICATIONS ZT710 ZT720 ZT730 ZT740 Crankcase Breather Assembly Breather Reed Cover Stud Breather Reed Cover Hex Nut Breather Cover Fastener 6 2 N m 55 in Ib into new hole 4 0 N m 35 in Ib into used hole 1 3 N m 12 in Ib 8 5 4 0 2 m 75 Ib into new hole m 35 in Ib into used hole z Oil Drain Plug 13 6 N m 10 ft Ib Cylinder Head Head Bolt Fastener torque in 2 increments first to 22 6 N m 200 in Ib finally to 41 8 N m 370 in Ib Rocker Arm Stud 11 3 N m 100 in lb Rocker Arm Adjuster Setscrew 7 9 70 in lb Module Fastener Flywheel Retaining Screw 74 5 55 f
54. cess fuel or oil in combustion chamber Excess fuel could be caused by a restricted air cleaner a carburetor problem or operating engine with too much choke Oil in combustion chamber is usually caused by a restricted air cleaner a breather problem worn piston rings or valve guides KohlerEngines com 31 Electrical System Carbon Fouled Battery Maintenance T maintenance is necessary to prolong battery ife Battery Test To test battery follow manufacturer s instructions ELECTRONIC IGNITION SYSTEMS All ignition systems are designed to be trouble free for life of engine Other than periodically checking replacing spark plugs no maintenance or timing adjustments are necessary or possible Mechanical systems do Soft sooty black deposits indicate incomplete combustion caused by a restricted air cleaner over rich carburetion weak ignition or poor compression Overheated occasionally fail or break down Refer to Troubleshooting to determine root of a reported problem Reported ignition problems are most often due to poor connections Before beginning test procedure check 6 all external wiring Be certain all ignition related wires are connected including spark plug leads Be certain all terminal connections fit snugly Make sure ignition switch is in run position Chalky white deposits indicate very high combustion temperatures This condition is usually accomp
55. d exhaust Recondition piston rings cylinder bore valves and valves guides Check exhaust screen spark arrestor if equipped Clean or replace as needed Repair or replace any other damaged restricted muffler or exhaust system parts 18 KohlerEngines com 16 690 01 Rev Troubleshooting COMPRESSION TEST For Command Twins A compression test is best performed on a warm engine Clean any dirt or debris away from base of spark plug s before removing them Be sure choke is off and throttle is wide open during test Compression should be at least 160 psi and should not vary more than 15 between cylinders All other models These engines are equipped with an automatic compression release ACR mechanism It is difficult to obtain an accurate compression reading because of ACR mechanism As an alternative use cylinder leakdown test described below CYLINDER LEAKDOWN TEST A cylinder leakdown test can be a valuable alternative to a compression test By pressurizing combustion chamber from an external air source you can determine if valves or rings are leaking and how badly Cylinder leakdown tester is a relatively simple inexpensive leakdown tester for small engines This tester includes a quick connect for attaching adapter hose and a holding tool 1 Run engine for 3 5 minutes to warm it up 2 Remove spark plug s and air filter from engine 3 Rotate crankshaft until piston of cylinder being tested is
56. ditioning is necessary If bearing surfaces are worn or damaged crankcase and or oil pan will need to be replaced Inspect crankshaft keyways If worn or chipped replacement of crankshaft will be necessary Inspect crankpin for score marks or metallic pickup Slight score marks can be cleaned with crocus cloth soaked in oil If wear limits are exceeded as stated in Specifications it will be necessary to replace crankshaft Remove Flywheel and PTO End Oil Seals Remove oil seals from crankcase and oil pan 58 KohlerEngines com Crankcase Inspection and Service Check all gasket surfaces to make sure they are free of gasket fragments Gasket surfaces must also be free of deep scratches or nicks Check cylinder bore for scoring In severe cases unburned fuel can cause scuffing and scoring of cylinder wall It washes necessary lubricating oils off piston and cylinder wall As raw fuel seeps down cylinder wall piston rings make metal to metal contact with wall Scoring of cylinder wall can also be caused by localized hot spots resulting from blocked cooling fins or from inadequate or contaminated lubrication If cylinder bore is badly scored excessively worn tapered or out of round resizing is necessary Use an inside micrometer to determine amount of wear refer to Specifications A 0 25 mm 0 010 in oversize piston is available if resizing is selected Initially resize using a boring bar then use these following proc
57. e Correct any observed problem and reconnect line Fuel line condition 16 690 01 Rev Check for a clogged fuel line If fuel line is unobstructed check for overfilled crankcase and or oil in pulse line If checks don t reveal cause of problem replace pump KohlerEngines com 21 Fuel System CARBURETOR A WARNING Explosive Fuel can cause fires and severe burns 2 Do not fill fuel tank while engine is hot or running Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupied buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent Keihin One Barrel Carburetor Components Walbro One Barrel Carburetor Components A Idle Speed Screw B Carburetor Body C Main Jet D Float Shut off Solenoid E Fuel Bowl F Assembly G Choke Lever Engines in this series are equipped with either a Keihin or Walbro fixed main jet carburetor Most carburetors utilize a fuel shut off solenoid and feature a self relieving choke Troubleshooting Checklist When engine starts hard runs rough or stalls at low idle speed check these areas before adjusting or disassembling carburetor 1 2 Make sure
58. e Faulty carburetor Faulty cylinder head gasket Faulty or misadjusted choke or throttle controls Fuel pump malfunction vacuum hose clogged or leaking e Intake system leak e Loose wires or connections that intermittently ground ignition kill circuit e Quality of fuel dirt water stale mixture e Restricted fuel tank cap vent Engine Starts Hard e Carburetor adjusted incorrectly e Engine overheated e Faulty spark plug s e Ignition module s faulty or improperly gapped e Incorrect crankshaft position sensor air gap e Interlock switch is engaged or faulty e Loose wires or connections that intermittently ground ignition kill circuit e Quality of fuel dirt water stale mixture e Spark plug lead s disconnected e Spark plug lead boot loose on plug e Spark plug lead loose Engine Will Not Idle e Engine overheated e Faulty spark plug s e Idle fuel adjusting needle s improperly set e Idle speed adjusting screw improperly set e Inadequate fuel supply Low compression e Quality of fuel dirt water stale mixture e Restricted fuel tank cap vent Engine Overheats Clogged fuel line or fuel filter Engine overheated Faulty ACR mechanism Faulty or misadjusted choke or throttle controls Faulty spark plug s Flywheel key sheared Fuel pump malfunction vacuum hose clogged or leaking e Interlock switch is engaged or faulty e Loose wires or connections that inter
59. easy out and remove original choke shaft bushing with old choke lever from carburetor housing Save bushing to use as a driver for installing new bushing Discard old lever Clean I D of both choke shaft bores as required Insert new bushing through new choke lever from outside and start bushing in outer shaft bore Position choke lever so that protruding boss on carburetor housing is between two stops formed in choke lever Turn old bushing upside down and use it as a driver to carefully press or tap new bushing into carburetor body until it bottoms Check that choke lever pivots freely without restriction or binding Install new return spring onto new choke shaft so upper leg of spring is between two formed stops on end of choke shaft Slide choke shaft and spring into carburetor Pivot preload shaft and set inner leg of spring against formed stop within choke lever as originally assembled Opposing leg of spring must still be between formed stops of choke shaft Place a drop of Loctite on threads of each new screw Install new choke plate to flat side of choke shaft and start two screws Larger cutout must be on right Close choke and check plate alignment within carburetor throat then tighten screws securely Do not overtighten Check for proper operation and free movement of parts Install new cap Clean carburetor body jets vent ports seats etc using a good commercially available carburetor solvent Use c
60. ed through idle port passage At low idle air fuel mixture is controlled by setting of idle fuel adjusting screws This mixture is then mixed with main body of air and delivered to engine As throttle plate opening increases greater amounts of air fuel mixture are drawn in through fixed and metered idle progression holes As throttle plate opens further vacuum signal becomes great enough at venturi so main circuit begins to work Main high speed At high speeds loads engine operates on main circuit As ametered amount of air is drawn through air jet fuel is drawn through main jet Air and fuel are mixed in main nozzles then enters main body of airflow where further mixing of fuel and air occurs This mixture is then delivered to combustion chamber Carburetor has a fixed main circuit no adjustment is possible KohlerEngines com 23 Fuel System Carburetor Adjustments Float Setting Keihin Only NOTE Carburetor adjustments should be made only after engine has warmed up Carburetor is designed to deliver correct fuel to air mixture to engine under all operating conditions Main fuel jet is calibrated at factory and is not adjustable Idle fuel adjusting needles are also set at factory and are not adjustable b Speed RPM Adjustment Hold governor lever away from carburetor so throttle lever is against idle speed RPM adjustment screw of carburetor Start engine and allow to warm up then adjust screw to set approxim
61. edures for honing cylinder Honing Details f d A 23 33 Crosshatch NOTE Kohler pistons are custom machined to exacting tolerances When over sizing a cylinder it should be machined exactly 0 25 mm 0 010 in over new diameter refer to Specifications Oversize Kohler replacement piston will then fit correctly While most commercially available cylinder hones can be used with either portable drills or drill presses use of a low speed drill press is preferred as it facilitates more accurate alignment of bore in relation to crankshaft crossbore Honing is best accomplished at a drill soeed of about 250 RPM and 60 strokes per minute After installing coarse stones in hone proceed as follows 1 Lower hone into bore and after centering adjust so stones are in contact with cylinder wall Use of a commercial cutting cooling agent is recommended 2 With lower edge of each stone positioned even with lowest edge of bore start drill and honing process Move hone up and down while resizing to prevent formation of cutting ridges Check size frequently 16 690 01 Rev 3 When bore is within 0 064 mm 0 0025 in of desired size remove coarse stones and replace them with burnishing stones Continue with burnishing stones until bore is within 0 013 mm 0 0005 in of desired size and then use finish stones 220 280 grit and polish bore to its final size Acrosshatch should be observed if honing is done cor
62. el lines e In line fuel filter e Fuel pump e Carburetor Fuel from tank is moved through in line filter and fuel lines by fuel pump Fuel then enters carburetor float bowl and is drawn into carburetor body and mixed with air This fuel air mixture is then burned in engine combustion chamber FUEL RECOMMENDATIONS Refer to Maintenance FUEL LINE Low permeation fuel line must be installed on carbureted Kohler Co engines to maintain EPA and CARB regulatory compliance FUEL PUMP Some engines use a pulse style fuel pump Pumping action of pulse style pumps is created by oscillation of positive and negative pressures within crankcase This pressure is transmitted to pulse pump through rubber hose connected between pump and crankcase Pumping action causes diaphragm on inside of pump to pull fuel in on its downward stroke and to push it into carburetor on its upward stroke Two check valves prevent fuel from going backward through pump FUEL SYSTEM TESTS Fuel System Performance Minimum fuel delivery rate must be 7 5 I hr 2 gal hr with a pressure at 0 3 psi and a fuel lift of 24 in A 1 3 Ihr 0 34 gal hr fuel rate must be maintained at 5 Hz Fuel Pump Replacement NOTE Make sure orientation of new pump is consistent with removed pump Internal damage may occur if installed incorrectly To replace pulse pump follow these steps Note orientation of pump before removing 1 Disconnect fuel lines from
63. enable choke to be placed ON 1 Loosen control cable clamp 2 Place throttle control lever of equipment into fast or high speed position 3 Pull on outer shield of throttle control cable until speed control lever rotates and makes contact with choke lever Tighten cable clamp securely Starting an Engine Equipped with Unitized Throttle and Choke Conirol NOTE Do not crank engine continuously for more than 10 seconds at atime If engine does not start allow a 60 second cool down period between starting attempts Failure to follow these guidelines can burn out starter motor NOTE If engine develops sufficient speed to disengage starter but does not keep running a false start engine rotation must be allowed to come to a complete stop before attempting to restart engine If starter is engaged while flywheel is rotating starter pinion and flywheel ring gear may clash resulting in damage to starter 1 For a Cold or Warm Engine Place throttle choke control into fast choke ON position This will also place choke into ON position 2 Make sure equipment is in neutral 3 Activate starter switch Release switch as soon as engine starts If starter does not turn engine over shut starter off immediately Do not make further attempts to start engine until condition is corrected Do not jump start using another battery See your Kohler authorized dealer for trouble analysis 4 For Operation After engine starts
64. er Intake Air Cleaner Intake e Replace air cleaner element if equipped with precleaner Air Cleaner Intake e Change oil and filter Lubrication System e Remove cooling shrouds and clean cooling areas Air Cleaner Intake Every 100 Hours e Check that all fasteners are in place and components are properly secured Reassembly e Replace fuel filter Every 500 Hours e Have valve clearance lash checked adjusted Reassembly Every 500 Hours e Replace spark plugs and set gap 1 Perform these procedures more frequently under severe dusty dirty conditions 2 Have a Kohler authorized dealer perform this service REPAIRS SERVICE PARTS Electrical System Kohler genuine service parts can be purchased from Kohler authorized dealers To find a local Kohler authorized dealer visit KohlerEngines com or call 1 800 544 2444 U S and Canada 16 690 01 Rev KohlerEngines com Maintenance OIL RECOMMENDATIONS We recommend use of Kohler oils for best performance Other high quality detergent oils including synthetic of API American Petroleum Institute service class SJ or higher are acceptable Select viscosity based on air temperature at time of operation as shown in table below L wa F 20 0 20 32 40 50 60 80 100 0 30 20 A0 0 10 20 30 40 FUEL RECOMMENDATIONS A WARNING Explosive Fuel can cause fires and severe burns
65. ere injury or death Disconnect and ground Lee spark plug lead s before 24 servicing A CAUTION Electrical Shock cause injury We Do not touch wires while engine is running Before working on engine or equipment disable engine as follows 1 Disconnect spark plug lead s 2 Disconnect negative battery cable from battery A WARNING Ro Rotating Parts can cause Iw Severe injury Stay away while engine is in operation WARNING A CAUTION Damaging Crankshaft and Flywheel can cause Jo personal injury co Hot Parts can cause severe burns Sin EH Do not touch engine while operating or just after stopping Using improper procedures can lead to broken fragments Broken fragments could be thrown from engine Always observe and use precautions and procedures when installing flywheel Keep hands feet hair and clothing away from all moving parts to prevent injury Never operate engine with covers shrouds or guards removed Never operate engine with heat shields or guards removed A WARNING Carbon Monoxide can cause severe nausea fainting or death Avoid inhaling exhaust fumes Engine exhaust gases contain poisonous carbon monoxide Carbon monoxide is odorless colorless and can cause death if inhaled A WARNING Cleaning Solvents can f cause severe injury or deat
66. ers heads and backing plate Remove Throttle Controls Control Bracket Components A Choke Linkage B Throttle Linkage C Governor Lever D Governor Spring E Cross Shaft F Control Bracket G Dampener Spring 1 Remove screws securing throttle control bracket to cylinder heads 2 Disconnect choke linkage from choke actuator lever Unhook governor spring and dampener spring from governor lever Note hole locations for reassembly Remove External Governor Controls Loosen nut and remove governor lever from cross shaft Leave lever attached to throttle linkage KohlerEngines com 49 Disassembly Inspection and Service Remove Air Cleaner and Carburetor Remove Inner Baffles WARNING Explosive Fuel can cause fires and severe 9 burns 4 Do not fill fuel tank while engine is hot or running iow Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupied buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent 1 Remove carburetor air cleaner base mounting nuts and disconnect breather hose Remove air cleaner base and gasket 2 Remove air cleaner element and precleaner if equipped from air cleaner base for servicing 3 Disconnect ground lead and fue
67. etaining rings and brushes Individual component available Starter Brush Holding Tool Solenoid Shift Kohler 25 761 20 S Kohler 25 761 41 S Design Technology Inc DTI 031 DTI 033 Kohler 25 761 40 S SE Tools KLR 82411 SE Tools KLR 82416 Triad OHC Timing Tool Set For holding cam gears and crankshaft in timed position while installing timing belt Kohler 28 761 01 S Valve Guide Reamer K and M Series For properly sizing valve guides after installation Design Technology Inc DTI K828 Valve Guide Reamer O S Command Series For reaming worn valve guides to accept replacement oversize valves Can be used in low speed drill press or with handle below for hand reaming Reamer Handle For hand reaming using Kohler 25 455 12 S reamer Valve Guide Service Kit Courage Aegis Command OHC For servicing worn valve guides AIDS Description Kohler 25 455 12 S Design Technology Inc DTI K8 SE Tools KLR 82415 Source Part No Camshaft Lubricant Valspar ZZ613 Kohler 25 357 14 S Dielectric Grease GE Novaguard G661 Kohler 25 357 11 S Dielectric Grease Loctite 51360 Kohler Electric Starter Drive Lubricant Inertia Drive Kohler 52 357 01 S Kohler Electric Starter Drive Lubricant Solenoid Shift Kohler 52 357 02 S RTV Silicone Sealant Loctite 5900 Heavy Body in 4 oz aerosol dispenser Only oxime based oil resistant RTV sealants such as those listed
68. f RTV sealant to perimeter flange of cover as shown Use Loctite 5900 or 5910 Immediately install breather reed cover over mounting stud and onto crankcase Do not allow RTV sealant to come in contact with breather reed or reed sealing surface Secure with a new sealing washer and M5 nut Torque nut to 1 3 N m 12 in Ib Check that a complete seal has occurred by RTV sealant being squeezed out around entire flange perimeter Install Stator and Backing Plate 1 2 64 Apply pipe sealant with Teflon Loctite PST 592 or equivalent to stator mounting holes Position stator aligning mounting holes so leads are at bottom toward crankcase Install and torque screws to 8 8 N m 78 in Ib Install backing plate Secure with screws Torque Screws in a crisscross pattern to 7 3 N m 65 in Ib caution Damaging Crankshaft and Flywheel can Yo cause personal injury Oy Using improper procedures can lead to broken fragments Broken fragments could be thrown from engine Always observe and use precautions and procedures when installing flywheel NOTE Before installing flywheel make sure crankshaft taper and flywheel hub are clean dry and completely free of lubricants Presence of lubricants can cause flywheel to be overstressed and damaged when screw is torqued to specifications NOTE Make sure flywheel key is installed properly in keyway Flywheel can become cracked
69. for leakdown test on XT 6 engines For checking combustion retention and if cylinder piston rings or valves are worn Kohler 25 761 05 S Design Technology Inc DTI 731 03 Dealer Tool Kit Domestic Complete kit of Kohler required tools Components of 25 761 39 S Ignition System Tester Cylinder Leakdown Tester Oil Pressure Test Kit Rectifier Regulator Tester 120 V AC 60Hz Kohler 25 761 39 S Kohler 25 455 01 S Kohler 25 761 05 S Kohler 25 761 06 S Kohler 25 761 20 S Dealer Tool Kit International Complete kit of Kohler required tools Components of 25 761 42 S Ignition System Tester Cylinder Leakdown Tester Oil Pressure Test Kit Rectifier Regulator Tester 240 V AC 50Hz Kohler 25 761 42 S Kohler 25 455 01 S Kohler 25 761 05 S Kohler 25 761 06 S Kohler 25 761 41 S Digital Vacuum Pressure Tester Design Technology Inc For checking crankcase vacuum DTI 721 01 Individual component available Design Technology Inc Rubber Adapter Plug DTI 721 10 Electronic Fuel Injection EFI Diagnostic Software For Laptop or Desktop PC Kohler 25 761 23 S EFI Service Kit For troubleshooting and setting up an EFI engine Components of 24 761 01 S Fuel Pressure Tester Kohler 24 761 01 S Design Technology Inc DTI 019 Noid Light DTI 021 90 Adapter DTI 023 In line T Fitting DTI 035 Code Plug Red Wire DTI 027 Code Plug Blue Wire DTI 029 Shrader Valve Adapter Hose DTI 037 Fl
70. for servicing starter drive 16 690 01 Rev Starter System SOLENOID SHIFT STARTERS Solenoid Shift Starter Components A Tube B Washer C Armature D Drive E Stop F Retaining Ring G Collar H Drive End Cap Screw J Plunger K Spring L Lever M Plate N Plug Solenoid P Frame and Field Q Brush Holder R Nut S ERU d End 1 Screw U Bolt When power is applied to starter electric solenoid moves drive pinion out onto drive shaft and into mesh with flywheel ring gear When pinion reaches end of drive shaft it rotates flywheel and cranks engine When engine starts and start switch is released starter solenoid is deactivated drive lever moves back and drive pinion moves out of mesh with ring gear into retracted position KohlerEngines com 39 Starter System Starter Disassembly NOTE Do not reuse old retainer NOTE Do not soak armature or use solvent when cleaning Wipe clean using a soft cloth or use compressed air 1 Remove hex nut and disconnect positive brush lead bracket from solenoid terminal 2 Remove head screws securing solenoid to starter 3 Unhook plunger pin from drive lever Remove gasket from recess in housing 4 Remove thru larger bolts 5 Remove commutator end plate assembly containing brush holder brushes springs and locking caps Remove thrust washer from inside commutator end 6 Remove frame from armature and dr
71. gine side is lower than level in open side pressure check for conditions in table below 4 Close pinch clamp before stopping engine Condition To test crankcase vacuum with vacuum pressure gauge 1 Remove dipstick or oil fill plug cap 2 Install adapter into oil fill dipstick tube opening upside down over end of a small diameter dipstick tube or directly into engine if a tube is not used Insert barbed gauge fitting into hole in stopper 3 Run engine and observe gauge reading Analog tester needle movement to left of 0 is a vacuum and movement to right indicates a pressure Digital tester depress test button on top of tester Crankcase vacuum should be a minimum of 10 2 cm 4 in of water If reading is below specification or if pressure is present check table below for possible causes and conclusions Conclusion Crankcase breather clogged or inoperative NOTE If breather is integral part of valve cover and cannot be serviced separately replace valve cover and recheck pressure Disassemble breather clean parts thoroughly check sealing surfaces for flatness reassemble and recheck pressure Seals and or gaskets leaking Loose or improperly torque fasteners Replace all worn or damaged seals and gaskets Make sure all fasteners are tightened securely Use appropriate torque valves and sequences when necessary Piston blow by or leaky valves confirm by inspecting components Restricte
72. h Use only in well ventilated areas away from ignition sources Ca A WARNING Uncoiling Spring can cause severe injury N Wear safety goggles or face protection when servicing retractable starter Carburetor cleaners and solvents are extremely flammable Follow cleaner manufacturer s warnings and instructions on its proper and safe use Never use gasoline as a cleaning agent Retractable starters contain a powerful recoil spring that is under tension Always wear safety goggles when servicing retractable starters and carefully follow instructions in Retractable Starter for relieving spring tension KohlerEngines com 16 690 01 Rev MAINTENANCE INSTRUCTIONS Maintenance E A WARNING s Accidental Starts can cause severe injury or Before working on engine or equipment disable engine as We Disconnect and ground spark plug lead s M before servicing death follows 1 Disconnect spark plug lead s 2 Disconnect negative battery cable from battery Normal maintenance replacement or repair of emission control devices and systems may be performed by any repair establishment or individual however warranty repairs must be performed by a Kohler authorized dealer MAINTENANCE SCHEDULE Every 25 Hours e Service replace precleaner e Replace air cleaner element if not equipped with precleaner Every 100 Hours Air Clean
73. her reed broken e Clogged broken or inoperative crankcase breather e Loose or improperly torqued fasteners e Piston blow by or leaky valves e Restricted exhaust 16 690 01 Rev KohlerEngines com Troubleshooting EXTERNAL ENGINE INSPECTION NOTE It is good practice to drain oil at a location away from workbench Be sure to allow ample time for complete drainage Before cleaning or disassembling engine make a thorough inspection of its external appearance and condition This inspection can give clues to what might be found inside engines and cause when it is disassembled e Check for buildup of dirt and debris on crankcase cooling fins grass screen and other external surfaces Dirt or debris on these areas can cause overheating e Check for obvious fuel and oil leaks and damaged components Excessive oil leakage can indicate a clogged or inoperative breather worn or damaged seals or gaskets or loose fasteners Check air cleaner cover and base for damage or indications of improper fit and seal Check air cleaner element Look for holes tears cracked or damaged sealing surfaces or other damage that could allow unfiltered air into engine A dirty or clogged element could indicate insufficient or improper maintenance Check carburetor throat for dirt Dirt in throat is further indication that air cleaner was not functioning properly Check if oil level is within operating range on dipstick If i
74. hlerEngines com 16 690 01 Rev Lubrication System This engine uses a combination pressure splash lubrication system delivering oil under pressure to crankshaft connecting rod and main bearing surfaces Other component areas are splash lubricated A high efficiency gerotor oil pump maintains high oil flow and oil pressure even at low speeds and high operating temperatures A pressure relief valve limits maximum pressure of system Oil pan must be removed to service oil pick up and oil pump Lubrication Components oe T T 4 lt 4 om e 000 5 B A Oil Fill Dipstick B Oil Drain Plug C Oil Filter OIL RECOMMENDATIONS CHANGE OIL AND FILTER Refer to Maintenance CHECK OIL LEVEL NOTE To prevent extensive engine wear or damage never run engine with oil level below or above operating range indicator on dipstick Ensure engine is cool Clean oil fill dipstick areas of any debris 1 2 3 16 690 01 Rev Remove dipstick wipe oil off Reinsert dipstick into tube press completely down Remove dipstick check oil level Level should be at top of indicator on dipstick If oil is low on indicator add oil up to top of indicator mark Reinstall and secure dipstick Change oil while engine is warm 1 2 Clean area around oil fill dipstick Remove drain plug and oil fill dipstick Allow oil to drain completely Clean area aro
75. inlet outlet and pulse fittings on fuel pump 2 Remove screws and take off pump 3 Connect pulse line to new fuel pump and make sure opposite end is properly connected into valve cover 4 Attach new fuel pump using screws Torque screws to 2 8 N m 25 in Ib 5 Reconnect fuel lines to inlet and outlet fittings and secure with clamps When engine starts hard or turns over but will not start fuel system might be causing problems Test fuel system by performing following test 1 Check for fuel in combustion chamber a Disconnect and ground spark plug leads b Close choke on carburetor c Crank engine several times d Remove spark plug and check for fuel at tip 2 Check for fuel flow from tank to fuel pump a Remove fuel line from inlet fitting of fuel pump b Hold line below bottom of tank Open shut off valve if equipped and observe flow Condition 3 Check operation of fuel pump a Remove fuel line from inlet fitting of carburetor b Crank engine several times and observe flow Conclusion Fuel at tip of spark plug Fuel is reaching combustion chamber No fuel at tip of spark plug Fuel flows from fuel line Check fuel flow from fuel tank step 2 Check for faulty fuel pump step 3 If fuel pump is working check for faulty carburetor Refer to Carburetor No fuel flow from fuel line Check fuel tank cap vent fuel pickup screen in line filter shut off valve and fuel lin
76. is at rest and throttle is in fast position tension of governor spring holds throttle plate open When engine is operating governor gear assembly is rotating Force applied by regulating pin against cross shaft tends to close throttle plate Governor spring tension and force applied by regulating pin balance each other during operation to maintain engine speed When load is applied and engine speed and governor gear speed decreases governor spring tension moves governor arm to open throttle plate wider This allows more fuel into engine increasing engine speed As speed reaches governed setting governor spring tension and force applied by regulating pin will again offset each other to hold a steady engine speed As flyweights move outward they cause regulating pin NOTE Do not tamper with governor setting Overspeed is hazardous and could cause personal injury Initial Adjustment Procedure Make this adjustment whenever governor arm is loosened or removed from cross shaft Adjust as follows 1 Make sure throttle linkage is connected to governor arm and throttle lever on carburetor 2 Loosen nut holding governor lever to cross shaft 3 Move governor lever toward carburetor as far as it will go wide open throttle and hold in this position 4 Insert a long thin rod or tool into hole on cross shaft and rotate shaft clockwise viewed from end as far as it will turn then torque nut to 6 8 N m 60 in Ib 28 Ko
77. ive end cap 7 Remove drive lever pivot bushing and backing plate if equipped from end cap 8 Take out drive lever and pull armature out of drive end cap 9 Remove thrust washer from armature shaft 10 Push stop collar down to expose retaining ring 11 Remove retainer from armature shaft Save stop collar 12 Remove drive pinion assembly from armature 13 Clean parts as required Inspection Drive Pinion Check and inspect following areas e Pinion teeth for abnormal wear or damage e Surface between pinion and clutch mechanism for nicks or irregularities which could cause seal damage e Check drive clutch by holding clutch housing and rotating pinion Pinion should rotate in only 1 direction Brushes and Springs Deiail A Wear Limit Length Inspect both springs and brushes for wear fatigue or damage Measure length of each brush Minimum length for each brush is 7 6 mm 0 300 in Replace brushes if they are worn undersize or condition is questionable 40 KohlerEngines com Armature Components and Details A Commutator O D B Mica Insulation Armature Coil Insulation Check D mo Continuity Check 1 Clean and inspect commutator outer surface Mica insulation must be lower than commutator bars undercut to ensure proper operation of commutator 2 Use an ohmmeter set to Rx1 scale Touch probes between 2 differe
78. l shut off solenoid lead if equipped 4 Remove carburetor throttle linkage and governor lever as an assembly 5 Remove carburetor gasket 6 If necessary carburetor throttle linkage and governor lever can be separated Reattach bushings to linkage following separation to avoid losing them Remove Electric Starter Motor if equipped 1 Disconnect leads from starter 2 Remove screws and starter 50 KohlerEngines com Remove mounting screws securing inner baffles to crankcase Note position of any lifting bracket s Remove inner baffles Remove Ignition Modules 1 Rotate flywheel so magnet is away from modules 2 Disconnect lead from each ignition module 3 Remove mounting screws and ignition modules Note position of ignition modules Remove Intake Manifold and Rectifier Regulator 1 Remove screws securing intake manifold to cylinder heads Note which screws hold wiring clamp s 2 Remove intake manifold and O rings Leave wiring harness attached to manifold 3 Remove screws securing rectifier regulator to backing plate and disconnect plug 4 Use tip of a small screwdriver or similar small flat tool to bend locking tang then remove B center lead from terminal plug This will allow intake manifold to be removed with wiring harness intact 16 690 01 Rev Cylinder Head Components Disassembly Inspection and Service A Gasket B Valve C Cylinder Head D
79. lastic carrier housing attached to end cap Replacement brushes in brush holder come preassembled attached to end cap with commutator end thrust washer cup holding brushes in retracted position When installation is performed end of armature shaft will push thrust washer cup back into final position allowing brushes to contact commutator Do not remove protective tape and shipping strip holding washer cup until part is ready to be installed Commutator Service Clean commutator with a coarse lint free cloth Do not use emery cloth If commutator is badly worn or grooved turn it down on a lathe or replace starter Starter Reassembly 1 Insert armature into starter frame Make sure magnets are closer to drive shaft end of armature Magnets will hold armature inside frame 2 Install drive end cap over drive shaft and align with cutout starter frame 3 Installing new brushes carefully remove tape holding thrust washer cup in place against brushes Do not allow thrust washer cup to move out of this position Align terminal stud block with notch in starter frame and start brush holder end cap assembly onto end of armature 4 Pull out thin shipping strip from behind thrust washer cup and slide brush holder end cap into position 5 Install thru bolts and torque to 4 5 5 7 N m 40 50 in Ib 6 Lubricate drive shaft with Kohler starter drive lubricant Install drive components following instructions
80. lean dry compressed air to blow out internal channels and ports Inspect and thoroughly check carburetor for cracks wear or damage Inspect fuel inlet needle seat for wear or damage Check spring loaded choke plate to make sure it moves freely on shaft Clean carburetor float bowl as required Install main nozzle and main jet into tower of carburetor body Install slow jet and new plug into end of slow jet tube Attach inlet needle to metal tang of float with wire clip Formed 90 lip of metal tang should point up with needle valve hanging down Install new float and new inlet needle down into seat and carburetor body Insert new pivot pin through float hinge and secure with new retaining screw 27 28 29 30 31 32 33 34 Fuel System Hold carburetor body so float assembly hangs vertically and rests lightly against fuel inlet needle Inlet needle should be fully seated but center pin of needle on retainer clip end should not be depressed Check float height adjustment Correct float height adjustment is 12 0 mm 0 472 in measured from float bottom to body of carburetor Adjust float height by carefully bending metal tang of float When proper float height is obtained carefully install new O ring for fuel bowl Install fuel bowl onto carburetor Secure with four original screws Torque screws to 2 5 3 Nem 23 2 6 in Ib Install new cover gasket and top cover on carburetor Sec
81. ll leak out of carburetor Have a container ready to catch fuel 2 Wipe tip of solenoid with a shop towel or blow with compressed air to remove any remaining fuel Take solenoid to a location with good ventilation and no fuel vapors present You will also need a 12 volt power source that can be switched on and off 3 Be sure power source is switched OFF Connect positive power source lead to red lead of solenoid Connect negative power source lead to solenoid body 4 Turn power source ON and observe pin in center of solenoid Pin should retract with power ON and return to its original position with power OFF Test several times to verify operation 16 690 01 Rev Carburetor Circuits Float Fuel level in bowl is maintained by float and fuel inlet needle Buoyant force of float stops fuel flow when engine is at rest When fuel is being consumed float will drop and fuel pressure will push inlet needle away from seat allowing more fuel to enter bowl When demand ceases buoyant force of float will again overcome fuel pressure rising to predetermined setting and stop flow Slow and Mid Range At low speeds engine operates only on slow circuit As a metered amount of air is drawn through slow air bleed jets fuel is drawn through main jet and further metered through slow jet Air and fuel are mixed in body of slow jet and exit to idle progression transfer port chamber From idle progression chamber air fuel mixture is meter
82. lly remove main jet from carburetor After main jet is removed on some carburetors main nozzle can be removed through bottom of main tower Note orientation direction of nozzle Save parts for cleaning and reuse 8 Position of slow jet varies and is removable only on some styles of carburetors See correct illustration for corresponding style of carburetor showing location Save parts for cleaning and reuse unless a jet kit is also being installed Clean slow jet using compressed air Do not use wire or carburetor cleaner 9 Carburetor is now disassembled for appropriate cleaning and installation of parts in overhaul kit Further disassembly is not necessary Throttle shaft assembly fuel inlet seat and idle fuel adjustment screw are non serviceable items and should not be removed Choke shaft assembly is serviceable however it should not be removed unless a choke repair kit will be installed 16 690 01 Rev For Keihin Carburetors Only 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 16 690 01 Rev To install choke repair kit go to step 10 otherwise go to step 21 Remove and discard plastic cap from top of choke lever shaft assembly Note position of spring legs and choke plate for correct reassembly later Remove two screws attaching choke plate to choke shaft Pull shaft out of carburetor body and discard removed parts Use a screw extractor
83. measurements Always use a micrometer Before installing piston into cylinder bore it is necessary that clearance be accurately checked This step is often overlooked and if clearances are not within specifications engine failure will usually result 16 690 01 Rev Disassembly Inspection and Service Use following procedure to accurately measure piston to bore clearance 1 Use a micrometer and measure diameter of piston 6 mm 0 2362 in above bottom of piston skirt and perpendicular to piston pin 2 Use an inside micrometer telescoping gauge or bore gauge and measure cylinder bore Measurement approximately 63 5 mm 2 5 in below top of bore and perpendicular to piston pin 3 Piston to bore clearance is difference between bore diameter and piston diameter step 2 minus step 1 KohlerEngines com 59 Reassembly NOTE Make sure engine is assembled using all specified torque values tightening sequences and clearances Failure to observe specifications could cause severe engine wear or damage Always use new gaskets Make sure all traces of any cleaner are removed before engine is assembled and placed into operation Even small amounts of these cleaners can quickly break down lubricating properties of engine oil Check oil pan crankcase cylinder heads and valve covers to be certain all old sealing material has been removed Use gasket remover lacquer thinner or paint remover to remove any remaining traces
84. med simultaneously for both cylinders However if only 1 tester is available 2 individual tests must be performed Side not being tested must have spark plug lead connected or grounded Do not crank engine or perform tests with 1 spark plug lead disconnected and not grounded or permanent system damage may occur 1 With engine stopped disconnect 1 spark plug lead Connect spark plug lead to post terminal of spark tester and attach tester clip to a good engine ground 2 Crank engine over establishing a minimum of 550 600 RPM and observe tester s for spark 3 Repeat spark test on opposite cylinder if cylinders are being tested individually Condition Possible Cause Conclusion One side is not firing Wiring and Connections Check all wiring connections and terminals on that side If wiring is okay replace ignition module and retest for spark Tester shows spark but engine Spark Plug s Try new spark plug s misses or won t run on that cylinder Neither side is firing Ignition Switch Recheck position of ignition switch and check for shorted kill lead Both cylinders have good spark but Spark Plug s Install new spark plug s and retest engine runs poorly or existing plug engine performance condition is questionable 1 cylinder has good spark and other Ignition Test ignition modules and cylinder has no or intermittent spark connections 34 KohlerEngines com 16 690 01 Rev Electrical System
85. mittently ground ignition kill circuit e Low compression e Quality of fuel dirt water stale mixture e Weak spark 16 KohlerEngines com e Cooling fan broken e Excessive engine load e Fan belt failed off e Faulty carburetor e High crankcase oil level e Lean fuel mixture e Low cooling system fluid level e Low crankcase oil level e Radiator and or cooling system components clogged restricted or leaking e Water pump belt failed broken e Water pump malfunction Engine Knocks e Excessive engine load e Hydraulic lifter malfunction e Incorrect oil viscosity type e Internal wear or damage e Low crankcase oil level e Quality of fuel dirt water stale mixture 16 690 01 Rev Engine Loses Power e Dirty air cleaner element e Engine overheated e Excessive engine load e Restricted exhaust e Faulty spark plug s e High crankcase oil level e Incorrect governor setting e Low battery e Low compression e Low crankcase oil level e Quality of fuel dirt water stale mixture Engine Uses Excessive Amount of Oil e Loose or improperly torqued fasteners e Blown head gasket overheated e Breather reed broken e Clogged broken or inoperative crankcase breather e Crankcase overfilled e Incorrect oil viscosity type e Worn cylinder bore e Worn or broken piston rings e Worn valve stems valve guides Oil Leaks from Oil Seals Gaskets e Breat
86. n 2 increments first to 7 4 N m 66 in Ib then to 9 9 N m 88 in Ib 2 Connect kill lead to tab terminal on standard ignition modules 68 KohlerEngines com 42 warninc Explosive Fuel can cause fires and severe 9 burns 4 Do not fill fuel tank while engine is hot or running Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupied buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent 1 Install a new carburetor gasket Make sure all holes align and are open 2 Install carburetor throttle linkage and governor lever as an assembly 3 If carburetor is equipped with a fuel solenoid connect red power lead Attach eyelet terminal of ground lead to inner top carburetor cover mounting Screw 16 690 01 Rev Install External Governor Controls Control Bracket Components Reassembly 4 Install a new air cleaner base gasket and air cleaner base onto mounting studs Torque nuts to 6 2 7 3 N m 55 65 in Ib 5 Connect breather hose to air cleaner base and secure with clamp 6 Move governor lever toward carburetor as far as it will go wide open throttle and hold in position 7 Insert a nail or similar tool into hole on cross shaft and rotate shaft counterclockwi
87. n ignition modules Ignition timing varies depending upon engine speed with this system A typical fixed ignition system consists of e 1 magnet assembly which is permanently affixed to flywheel e 2 electronic capacitive discharge or magnetic discharge ignition modules which mount on engine crankcase e 1 kill switch or key switch which grounds modules to stop engine e 2 spark plugs Wiring Diagram Electronic Ignition System Diagram Solenoid Shift Inertia Driver A Starter Solenoid Tang B Starter Assembly C Starter Assembly Violet Charging F Oil Sentry Optional G Spark Plug s H AC Sharing Leads Rectifier Regulator ei Flywheel Stator I Connector J Rectifier Regulator K Assembly L Ignition Module s M Intake Manifold Screw N Ground Carburetor P White Ignition Kill Q Red R Solenoid Lead S Orange T Connector U Blue V Starter Solenoid Stud W Relay Stud X Y Battery Negative 2 Battery AA Battery Positive AB RE AC White Ap Orange shown Blue shown or Red AF Polarity Rib AG Solenoid Shift Starter Assembly Optional 16 690 01 Rev KohlerEngines com 33 Electrical System Electronic Ignition Systems Tests NOTE Igni
88. n magnet and ignition modules Make sure magnet does not strike modules Check gap with a feeler gauge and readjust if necessary Final air gap 0 203 0 305 mm 0 008 0 012 in Install Intake Manifold 1 Install B terminal lead into center position of rectifier regulator plug so it locks in place and connect plug to rectifier regulator 2 Attach rectifier regulator to opening in backing plate from underside and secure with mounting screws Torque screws to 4 0 N m 35 in Ib Install Inner and Outer Cylinder Baffles 1 Attach outer cylinder baffles and secure with M6 screw lower cylinder location and M5 screw into backing plate Tighten screws as listed following step 2 2 Attach inner baffles including any lifting straps to cylinder head flanges and to 2 crankcase mounting bosses Lift strap should be outside outer baffle Secure with M5 screws Remaining lower inner baffle mounting screws will be installed later Torque baffle mounting screws M5 screws 6 2 N m 75 in Ib into a new cored hole or 4 0 N m 35 in Ib into a used hole M6 screws 10 7 N m 95 in Ib into a new cored hole or 7 3 N m 65 in Ib into a used hole Install Carburetor Torque Sequence 1 Install intake manifold using new O rings with wiring harness attached onto cylinder heads Slide any wiring harness clips onto appropriate bolts before installing Using sequence shown torque screws i
89. nister Breather F Filter To Carburetor For engine to be Tier III compliant it may be fitted with a Kohler supplied canister vapor recovery system or a system developed and installed by Original Equipment Manufacturer OEM Details on Kohler system are included below Operation Maintenance Fuel vapors travel from fuel tank through tubing to carbon canister On intake stroke of engine fuel vapors are drawn in through a port in carburetor and burned with fuel charge 16 690 01 Rev On Kohler supplied canisters breather filter can be removed and cleaned with hot soapy water dried and reinstalled Do not oil breather screen This is done periodically or if system operation is suspect Carbon canister is sealed and requires no maintenance In some applications or installations OEM will have installed a different canister or fuel vapor recovery system See OEM equipment documentation for service or maintenance information KohlerEngines com 45 Emission Compliant Systems SECONDARY EMISSION COMPLIANT SYSTEM Twin Secondary Air Induction System Hose To Exhaust Secondary Air A Manifold B Inlet Screen C Valve Assembly D Hose To Carburetor E Hose To Exhaust Manifold Single Secondary Air Induction System F Secondary Air G Hose To Exhaust H Valve Assembly Manifold For engine to be Tier III compliant it may be fitted with a secondary air induction system
90. nkcase and replace it with a new one Install new seal to depth shown 56 KohlerEngines com Oil Seal Remove Breather Assembly Breather system is designed to control amount of oil in head area and still maintain necessary vacuum in crankcase When pistons move downward crankcase gases are pushed past reed through breather filter into intake system Upward travel of pistons closes reed and creates a low vacuum in lower crankcase Any oil separated out through filter drains back into crankcase 1 Remove screws securing breather cover to crankcase 2 Carefully remove cover and breather filter Make sure drain back hole is not plugged or restricted Remove Connecting Rods with Pistons and Rings NOTE If a carbon ridge is present at top of either cylinder bore use a ridge reamer tool to remove it before attempting to remove piston NOTE Cylinders are numbered on crankcase Use numbers to mark each end cap connecting rod and piston for reassembly Do not mix end caps and connecting rods 1 Remove screws securing closest connecting rod end cap Remove end cap 2 Carefully remove connecting rod and piston assembly from cylinder bore 3 Repeat above procedure for other connecting rod and piston assembly 16 690 01 Rev Connecting Rods Offset stepped cap connecting rods are used in all these engines Inspection and Service Check bearing area big end for excessive wear score marks r
91. noid hold in coil Function 1 Connect a 12 volt test lead to flat spade S start terminal on solenoid and other lead to body or mounting surface of solenoid 2 Manually push plunger IN and check if coil holds plunger retracted Do not allow test leads to remain connected to solenoid for a prolonged period of time Continuity 1 Use an ohmmeter set to audible or Rx2K scale and connect 2 ohmmeter leads to 2 large post terminals 2 Perform preceding solenoid hold in coil function test and check for continuity Meter should indicate continuity Repeat test several times Conclusion Solenoid fails to activate No continuity is indicated Plunger fails to stay retracted Replace solenoid 42 KohlerEngines com 16 690 01 Rev RETRACTABLE STARTERS Starter System A WARNING AS Wear safety goggles or face protection when servicing retractable starter Retractable starters contain a powerful recoil spring that is under tension Always wear safety goggles when servicing retractable starters and carefully follow instructions in Retractable Starter for relieving spring tension Uncoiling Spring can cause severe injury Retractable Starter Components y AN A ave fp J A Center Screw B Drive Plate C Friction Spring D Drive Pawl Dogs E Drive Pawl Springs F Pulley G Recoil Spring H Starter Rope Star
92. nt segments of commutator and check for continuity Test all segments Continuity must exist between all or armature is bad 3 Check for continuity between armature coil segments and commutator segments There should be no continuity If continuity exists between any 2 armature is bad 4 Check armature windings insulation for shorting Shift Fork Check that shift fork is complete and pivot and contact areas are not excessively worn cracked or broken Brush Replacement 4 brushes and springs are serviced as a set Use a new Kohler brush and spring kit if replacement is necessary 1 Perform steps 1 5 in Starter Disassembly 2 Remove screws securing brush holder assembly to end cap plate Note orientation for reassembly later Discard old brush holder assembly 3 Clean component parts as required New brushes and springs come preassembled in a brush holder with a protective sleeve that will also serve as an installation tool 4 Perform steps 10 13 in Starter Reassembly sequence If starter has been disassembled installation must be done after armature drive lever and frame are installed 16 690 01 Rev Starter Reassembly NOTE Always use a new retainer Do not reuse old retainers that have been removed NOTE Correctly installed center pivot section of drive lever will be flush or below machined surface of housing 1 Apply drive lubricant to armature shaft splines Install drive pinion onto
93. or damaged if key is not installed properly 1 Install flywheel key into keyway of crankshaft Make sure key is properly seated and parallel with shaft taper 2 Install flywheel onto crankshaft being careful not to shift flywheel key 3 Install fan onto flywheel so locating pins fit into corresponding recesses Drive 2 retainers down completely 4 Install fan mounting plate or drive cup if equipped onto fan aligning 4 cutouts followed by heavy flat washer and screw 5 Use a flywheel strap wrench or holding tool to hold flywheel Torque screw securing flywheel to crankshaft to 74 5 N m 55 ft Ib KohlerEngines com 16 690 01 Rev Cylinder Head Components Reassembly A Gasket B Valve C Cylinder Head D Valve Spring Cap E Valve Stem Seal F Valve Spring G Valve Spring Keeper H Stud Spark Plug J Guide Plate K Push Rod L Rocker Arm M Rocker Arm Pivots N Adjusters Washer P Valve Cover Assemble and Install Cylinder Heads Valve Stem Seals Use a new seal whenever valve is removed or if seal is deteriorated or damaged Never reuse an old seal Assemble Cylinder Heads Prior to installation lubricate all components with engine oil paying particular attention to lip of valve stem seal valve stems and valve guides Install following items in order listed below using a valve spring compressor e Intake and exhaust valves e Valve stem seal e Wa
94. or spring from throttle control bracket to appropriate hole in governor lever Install Electric Starter Motor if equipped 1 Install starter motor and lift bracket 2 Torque screws to 23 8 N m 211 in Ib 3 On models with a solenoid shift starter connect leads to solenoid Install Debris Screen if equipped Snap screen onto fan KohlerEngines com 69 Reassembly Install Blower Housing Fuel Pump Components NOTE Do not completely tighten screws until all are installed to allow shifting for hole alignment 1 Install blower housing onto engine Start all mounting screws Make sure wire harness and spark plug leads exit out through appropriate openings in shrouding Attach any fuel line clamps used 2 Torque screws as follows M5 Thread Forming Fasteners 3 4 N m 30 in Ib M4 HI LO Screws 2 8 N m 25 in Ib M3 HI LO Screws 2 3 N m 20 in Ib Install Fixed Guard if equipped Install fixed guard Securely tighten screw if equipped Install Retractable Starter if equipped 1 Install retractable starter on blower housing using screws Finger tighten mounting screws only 2 Pull rope handle to engage pawls and center starter to drive cup Hold in this position and torque mounting screws to 7 3 N m 65 in Ib Install Dipstick Tube 1 Lubricate dipstick tube O ring and install into crankcase 2 Secure to backing plate using M5 screw 3 Torque screw to 7 3 N m 65 in Ib
95. pe Insert knot into hole in handle 12 Untie slip knot and pull on starter handle until starter rope is fully extended Slowly retract starter rope into starter assembly If recoil spring is properly tensioned starter rope will retract fully and starter handle will stop against starter housing 44 KohlerEngines com 1 Install a clamp to hold pulley in starter housing and prevent it from rotating 2 Unscrew center screw and lift off drive plate 3 Note positions of pawls and pawl springs before removing Remove parts from pulley 4 Install pawl springs and pawls into pawl slots of pulley All parts must by dry 5 Position drive plate over pawls aligning actuating slots in place with raised sections on each drive pawl Torque center screw to 5 6 N m 44 54 in Ib 6 Remove clamp and pull starter rope out part way to check operation of pawls Install Starter 1 Install retractable starter onto blower housing leaving screws slightly loose 2 Pull starter handle out until pawls engage in drive cup Hold handle in this position and torque mounting screws to 7 3 N m 65 in Ib 16 690 01 Rev EVAPORATIVE EMISSION COMPLIANT SYSTEM Carbon Canister System Emission Compliant Systems B N T i Ke Lut Bi lt H 4 S CTK d E Li I r4 HER E AU PLL y 1 14 2 S ll Lie KN ac A Fuel Tank Cap B Fuel Tank C Roll oy D Carbon Canister E Ca
96. r regulator volts replace 16 690 01 Rev Starter System NOTE Do not crank engine continuously for more than 10 seconds Allow a 60 second cool down period between starting attempts Failure to follow these guidelines can burn out starter motor NOTE If engine develops sufficient speed to disengage starter but does not keep running a false start engine rotation must be allowed to come to a complete stop before attempting to restart engine If starter is engaged while flywheel is rotating starter pinion and flywheel ring gear may clash and damage starter NOTE If starter does not crank engine shut off starter immediately Do not make further attempts to start engine until condition is corrected NOTE Do not drop starter or strike starter frame Doing so can damage starter Engines in this series use inertia drive solenoid shift or retractable starters Troubleshooting Starting Difficulties Condition Possible Cause Conclusion Starter does not energize Battery Check specific gravity of battery If low recharge or replace battery as necessary Wiring Clean corroded connections and tighten loose connections Replace wires in poor condition and with frayed or broken insulation Starter Switch By pass switch or solenoid with a jumper wire If starter cranks or Solenoid normally replace faulty components Remove and perform individual solenoid test procedure Starter energizes but turns Battery Check specific
97. re camshaft gear and crankshaft gear mesh with both timing marks aligned Oil Pump Assembly A 6 5 0 255 B Oil Seal Oil pump is mounted inside oil pan If service was required and oil pump was removed refer to Disassembly Inspection and Service procedure Governor Assembly Governor assembly is located inside oil pan If service was required and governor was removed refer to Disassembly Inspection and Service procedure 62 KohlerEngines com 1 Check to make sure there are no nicks or burrs in crankshaft bore of oil pan 2 Apply a light coat of engine oil to outside diameter of oil seal 3 Drive oil seal into oil pan using a seal driver Make sure oil seal is installed straight and true in bore to depth shown 16 690 01 Rev Install Oil Pan Assembly Reassembly Flywheel Ignition Breather Components Sealant Pattern RTV sealant is used as a gasket between oil pan and crankcase Refer to Tools and Aids for a listing of approved sealants Always use fresh sealant Using outdated sealant can result in leakage he 2 3 16 690 01 Rev Be sure sealing surfaces have been cleaned and prepared as described at beginning of Reassembly Check to make sure there are no nicks or burrs on sealing surfaces of oil pan or crankcase Apply a 1 5 mm 1 16 in bead of black RTV sealant to sealing
98. rect engine operation at altitudes above 1219 meters 4000 ft To obtain high altitude kit information or to find a Kohler authorized dealer visit KohlerEngines com or call 1 800 544 2444 U S and Canada This engine should be operated in its original configuration below 1219 meters 4000 ft as damage may occur if high altitude carburetor kit is installed and operated below 1219 meters 4000 ft KohlerEngines com 25 Fuel System UNITIZED THROTTLE AND CHOKE CONTROL Some engines are equipped with a unitized throttle and choke control This assembly controls choke and engine speed with a single lever Engines with a unitized throttle and choke control will have either a left side pull or a right side pull Governor Throttle Control Connections Left Side Pull Choke Lever Cable Clamp Right Side Pull C Speed Control Lever Contact Point D Speed Setting Lever Choke Control Cable Throttle Control Cable Dual Control High Speed Lever Stop Screw Do Not Remove K High Speed Adjusting Screw Choke Linkage High Speed Control Lever 26 KohlerEngines com 16 690 01 Rev Throttle Cable Adjustment NOTE Choke is placed ON by moving throttle control slightly past fast position If throttle control does not have a designated choke ON position be sure to leave sufficient throttle control travel past fast position This will
99. rectly Crosshatch should intersect at approximately 23 33 off horizontal Too flat an angle could cause rings to skip and wear excessively and too steep an angle will result in high oil consumption 4 After resizing check bore for roundness taper and size Use an inside micrometer telescoping gauge or bore gauge to take measurements These measurements should be taken at 3 locations in cylinder at top middle and bottom Two measurements should be taken perpendicular to each other at 3 locations Clean Cylinder Bore After Honing Proper cleaning of cylinder walls following boring and or honing is very critical to a successful overhaul Machining grit left in cylinder bore can destroy an engine in less than 1 hour of operation after a rebuild Final cleaning operation should always be a thorough scrubbing with a brush and hot soapy water Use a strong detergent capable of breaking down machining oil while maintaining a good level of suds If suds break down during cleaning discard dirty water and start again with more hot water and detergent Following scrubbing rinse cylinder with very hot clear water dry it completely and apply a light coating of engine oil to prevent rusting Measuring Piston to Bore Clearance Piston Detail A 6 mm 0 2362 in NOTE Do not use a feeler gauge to measure piston to bore clearance it will yield inaccurate
100. roper seating Gauge reading in low green zone Piston rings and cylinder in good condition Gauge reading in moderate yellow zone Engine is still usable but there is some wear present Customer should start planning for overhaul or replacement Gauge reading in high red zone Rings and or cylinder have considerable wear Engine should be reconditioned or replaced 16 690 01 Rev KohlerEngines com 19 Air Cleaner Intake AIR CLEANER These systems are CARB EPA certified and components should not be altered or modified in any way Heavy Duty Air Cleaner Components Precleaner C Paper Element D Air Cleaner Base Low Profile Air Cleaner Components A Air Cleaner Cover B Precleaner C Paper Element D Air Cleaner Base NOTE Operating engine with loose or damaged air cleaner components could cause premature wear and failure Replace all bent or damaged components NOTE Paper element cannot be blown out with compressed air 20 KohlerEngines com Move bails on air cleaner cover up remove latches from cover remove cover Precleaner if equipped 1 Remove precleaner from paper element 2 Replace or wash precleaner in warm water with detergent Rinse and allow to air dry 3 Lightly oil precleaner with new engine oil squeeze out excess oil 4 Reinstall precleaner over paper element Paper Element 1 Separate precleaner from elemen
101. s and stator Note routing of stator leads Remove Outer Breather Assembly 1 RTV sealant is used between breather reed cover and crankcase Remove nut and sealing flat washer securing breather reed cover to crankcase Carefully pry under small tab of cover flange to separate and remove Do not bend or distort cover 2 Unscrew and remove mounting stud retainer and breather reed 54 KohlerEngines com Governor Cross A Shaft B Crankshaft C Valve Tappets D Camshaft E Regulating Pin F Shaft Locking Tab Thrust G Governor Gear H Washer l Oil Pan J Drain Plug K Oil Seal L Oil Pump M Oil Sentry zy N Ball O Spring P Oil Pick up Screen R Outer Gerotor Gear 16 690 01 Rev Remove Oil Pan Assembly 1 Remove screws securing oil pan to crankcase 2 Locate splitting tab cast into perimeter of oil pan Insert drive end of a 1 2 breaker bar between splitting tab and crankcase and turn it to break RTV seal Do not pry on sealing surfaces as this can cause leaks Inspection Inspect oil seal in oil pan and remove it if it is worn or damaged New oil seal is installed after oil pan is assembled to crankcase See Reassembly Install Oil Seal in Oil Pan Inspect main bearing surface for wear or damage refer to Specifications Replace oil pan assembly if required Governor Assembly Governor gear assembly is located inside oil
102. se as far as will turn then torque nut to 6 8 N m 60 in Ib Install Air Cleaner Element Install air cleaner element with precleaner if equipped onto air cleaner base Install Throttle and Choke Controls Governor Lever Hole Position A Choke Linkage B Throttle Linkage C Governor Lever D Governor Spring E Cross Shaft F Control Bracket G Dampener Spring Throttle and Choke Components A Screw B Choke Lever Throttle Actuator C Throttle Lever D Lever E Control Bracket Choke Return Spring G Lock Nut M5x0 8 H Shoulder Washer l Flat Washer J Nylon Washer K Wave Washer 1 Install governor lever onto governor cross shaft if disconnected previously 2 Make sure throttle linkage is connected to governor lever and throttle lever on carburetor Connect choke linkage to carburetor choke lever 3 Attach fuel line to carburetor and secure with a clamp 16 690 01 Rev A Governor Lever B Hole 1 C Hole 2 D Hole 3 E Hole 4 1 Connect choke linkage to choke actuator lever on main control bracket assembly 2 Install main control bracket to cylinder heads using screws Two lower screws should also secure inner baffles Torque screws to 10 7 N m 95 in Ib into new holes or 7 3 N m 65 in Ib into used holes 3 Connect governed idle spring to governor lever and main control bracket Connect govern
103. shaft Governor Gear Oil Pump Components NOTE Always use a flywheel strap wrench or flywheel holding tool see Tools and Aids to hold flywheel when loosening or tightening flywheel and fan retaining fasteners Do not use any type of bar or wedge between fins of cooling fan as fins could become cracked or damaged NOTE Always use a puller to remove flywheel from crankshaft Do not strike crankshaft or flywheel as these parts could become cracked or damaged Striking puller or crankshaft can cause crank gear to move affecting crankshaft endplay 1 Unsnap debris screen if equipped from cooling fan 2 Remove retaining screw washer and fan mounting plate or drive cup if equipped securing fan and tlywheel to crankshaft 3 Lift cooling fan to disengage 2 drive pins and remove it from flywheel Two plastic retainers may remain in fan 4 Remove flywheel from crankshaft by pulling from under ring gear with large gear puller 5 Remove flywheel key from crankshaft Flywheel Inspection Inspect flywheel for cracks and flywheel keyway for damage Replace flywheel if it is cracked Replace flywheel crankshaft and key if flywheel key is sheared or keyway is damaged Inspect ring gear for cracks or damage Kohler does not provide ring gears as a serviceable part Replace flywheel if ring gear is damaged Remove Backing Plate and Stator 1 Remove mounting screws and backing plate from crankcase 2 Remove screw
104. sher intake valve only e Valve springs e Valve spring caps e Valve spring keepers Install Cylinder Heads NOTE Match numbers embossed on cylinder heads and crankcase NOTE When installing cylinder heads new screws should always be used New screws are supplied in gasket sets NOTE Push rods should always be installed in same position as before disassembly 16 690 01 Rev Check to make sure there are no nicks or burrs on sealing surfaces of cylinder head or crankcase Make sure dowel locating pins are in lower 2 cylinder bolt holes on each side 2 Install a new cylinder head gasket with printing up on each side 3 Install each cylinder head and start 4 new screws 4 Torque screws in 2 stages first to 22 6 N m 200 in Ib then finally to 41 8 N m 370 in Ib following seguence Install Rocker Arms 1 Note mark or tag identifying push rod as either intake or exhaust and cylinder 1 or 2 Check each push rod is straight and not bent Dip ends of push rods in engine oil and install in their original positions making sure each push rod ball seats in its tappet socket 2 Install guide plate and studs Torque studs to 11 3 N m 100 in Ib 3 Apply grease to contact surfaces of adjusters rocker arms and rocker arm pivots Install rocker arms and rocker arm pivots onto appropriate cylinder head and install adjuster finger tight Make sure set screw is backed out until flush with adjuster
105. spring 38 KohlerEngines com Drive Service If drive pinion is worn or has chipped or broken teeth it must be replaced 1 Rubber dust cover has a molded lip on inside that snaps over a lip on front of drive pinion Turn drive pinion clockwise until it reaches fully extended position While holding it in extended position grasp tip of dust cover with a pliers or vise grip and pull it free from pinion 2 Grasp spring retainer with a pliers and push it toward starter compressing anti drift spring to expose retaining ring 3 Remove retaining ring from armature shaft using either a retaining ring pliers or snap ring removal tool as described in Steps 4 and 5 Do not reuse old retainer 4 Holding spring retainer in retracted position assemble inner halves of removal tool around armature shaft with retaining ring in inner groove Slide collar over inner halves to hold them in position 5 Thread center screw into removal tool until you feel resistance Use a wrench 1 1 8 or adjustable to hold base of removal tool Use another wrench or socket 1 2 or 13 mm to turn center screw clockwise Resistance against center screw will tell you when retaining ring has popped out of groove in armature shaft 6 Remove drive components from armature shaft paying attention to sequence If splines are dirty clean them with solvent 7 Splines should have a light film of lubricant Lubricate as necessary with Kohler starter drive
106. t Ib Fuel Pump Screw 2 8 N m 25 in Ib Governor Lever Nut 6 8 N m 60 in Ib Ignition Spark Plug 27 N m 20 ft Ib 4 0 6 2 N m 35 55 in Ib Rectifier Regulator Fastener 4 0 35 in Ib Intake Manifold Mounting Fastener torque in 2 increments first to 7 4 N m 66 in Ib finally to 9 9 N m 88 in Ib Muffler M8 Hex Nuts 24 4 N m 216 in lb 5 16 18 Capscrew 16 9 N m 150 in Ib Bracket Screw 9 9 N m 88 in Ib Oil Pan Fastener 24 4 N m 216 in lb Oil Pump Screw no torque sequence 9 9 N m 88 in Ib Oil Sentry Pressure Switch 4 5 40 in lb Values are in Metric units Values in parentheses are English equivalents 5 Lubricate threads with engine oil prior to assembly KohlerEngines com 16 690 01 Rev 8 Specifications TORQUE SPECIFICATIONS 5 ZT710 ZT720 ZT730 ZT740 Retractable Starter Mounting Screw 7 3 65 in Ib Center Screw 5 0 6 0 N m 44 54 in Ib Solenoid Starter Mounting Hardware 4 0 6 0 N m 35 53 in Ib Nut Positive Brush Lead 8 0 11 0 N m 71 97 in Ib Speed Control Bracket Fastener 10 7 N m 95 in Ib into new holes 7 3 N m 65 in Ib into used holes Starter Assembly Thru Bolt Inertia Drive 4 5 5 7 N m 40 50 in
107. t service precleaner and replace paper element 2 Install precleaner over new paper element and install on base Reinstall cover place latches onto cover pull down bails to secure cover Air Cleaner Base Disassembly Reassembly If air cleaner base requires removal proceed as follows 1 Remove mounting screws for fuel pump if equipped and blower housing 2 Raise or remove blower housing for access to air cleaner base 3 Remove air cleaner components from base 4 Remove nuts securing air cleaner base onto mounting studs 5 Disconnect breather hose from air cleaner base then remove base and gasket 6 Reverse procedure to reassemble components Torque nuts to 6 2 7 3 N m 55 65 in Ib Torque blower housing screws to 4 0 N m 35 in Ib and front HI LO screws to 2 8 N m 25 in Ib BREATHER TUBE Ensure both ends of breather tube are properly connected AIR COOLING A WARNING zt Hot Parts can cause severe burns pfi 6 KH Do not touch engine while operating or just after stopping Never operate engine with heat shields or guards removed Proper cooling is essential To prevent over heating clean screens cooling fins and other external surfaces of engine Avoid spraying water at wiring harness or any electrical components Refer to Maintenance Schedule 16 690 01 Rev Typical carbureted fuel system and related components include e Fuel tank e Fu
108. ter Handle Double Left Hand Knot KohlerEngines com 16 690 01 Rev Starter System Remove Starter Pawls dogs Replacement 1 Remove screws securing starter to blower housing 2 Remove starter assembly Rope Replacement NOTE Do not allow pulley spring to unwind Enlist aid of a helper if necessary Rope can be replaced without complete starter disassembly 1 Remove starter assembly from engine 2 Pull rope out approximately 12 in and tie a temporary slip knot in it to keep it from retracting into starter 3 Pull knot end out of handle untie knot and slide handle off 4 Hold pulley firmly and untie slipknot Allow pulley to rotate slowly as spring tension is released 5 When all spring tension on starter pulley is released remove rope from pulley 6 Tie a double left hand knot in one end of new rope 7 Rotate pulley counterclockwise to pre tension spring approximately 4 full turns of pulley 8 Continue rotating pulley counterclockwise until rope hole in pulley is aligned with rope guide bushing of starter housing 9 Insert unknotted end of new rope through rope hole in starter pulley and rope guide bushing of housing 10 Tie a slipknot approximately 12 in from free end of rope Hold pulley firmly and allow it to rotate slowly until slipknot reaches guide bushing of housing 11 Insert starter rope through starter handle and tie a double left hand knot at end of starter ro
109. tion tester must be used to test ignition on these engines Use of any other tester can result in inaccurate findings Battery on unit must be fully charged and properly connected before performing tests a battery that is hooked up or charged backward will crank engine but it won t have spark Be certain drive is in neutral and all external loads are disconnected Test Ignition Systems NOTE If engine starts or runs during testing you may need to ground kill lead to shut it down Because you have interrupted kill circuit it may not stop using switch Isolate and verify trouble is within engine 1 Locate connectors where wiring harnesses from engine and equipment are joined Separate connectors and remove white kill lead from engine connector Rejoin connectors and position or insulate kill lead terminal so it cannot touch ground Try to start engine to verify whether reported problem is still present Condition Possible Cause Conclusion Problem goes away Electrical System Check key switch wires connections safety interlocks etc Problem persists Ignition or Electrical System Leave kill lead isolated until all testing is completed Identify white kill lead of engine wiring harness connector Establish a connection to a known good ground location Engine should kill completely If not or only one cylinder is affected test ignition modules Test for Spark NOTE If 2 testers are available testing can be perfor
110. tis above sniff for gasoline odor Check condition of oil Drain oil into a container it should flow freely Check for metal chips and other foreign particles Sludge is a natural by product of combustion a small accumulation is normal Excessive sludge formation could indicate over rich fuel settings weak ignition overextended oil change interval or wrong weight or type of oil was used CLEANING ENGINE A WARNING Kh Cleaning Solvents can cause severe injury or death Use only in well ventilated areas away from ignition sources Carburetor cleaners and solvents are extremely flammable Follow cleaner manufacturer s warnings and instructions on its proper and safe use Never use gasoline as a cleaning agent After inspecting external condition of engine clean engine thoroughly before disassembly Clean individual components as engine is disassembled Only clean parts can be accurately inspected and gauged for wear or damage There are many commercially available cleaners that will quickly remove grease oil and grime from engine parts When such a cleaner is used follow manufacturer s instructions and safety precautions carefully Make sure all traces of cleaner are removed before engine is reassembled and placed into operation Even small amounts of these cleaners can quickly break down lubricating properties of engine oil 17 Troubleshooting CRANKCASE VACUUM TEST A WARNING
111. ttom of ring compressor and top of cylinder 5 Install inner rod cap to connecting rod using screws Torque screws in increments to 11 3 N m 100 in Ib Illustrated instructions are provided in service rod package 6 Repeat above procedure for other connecting rod and piston assembly Install Valve Tappets and Camshaft Install Oil Seal in Oil Pan Oil Seal Component and Detail NOTE Exhaust valve tappets are located on output shaft side of engine while intake valve tappets are located on fan side of engine Cylinder number is embossed on outside of each cylinder on crankcase Valve tappets should always be installed in same position as before disassembly 1 Apply camshaft lubricant to contact surface of valve tappets Note mark or tag identifying tappets and install them in their appropriate crankcase locations A small amount of grease applied to stems will hold valve tappets up until camshaft is installed 2 Liberally apply camshaft lubricant to lobes of camshaft Lubricate camshaft bearing surfaces of crankcase and camshaft with engine oil 3 Position timing mark of crankshaft gear at 12 o clock position 4 Turn governor cross shaft clockwise until lower end blade is laying against bottom of cylinder Make sure cross shaft remains in this position while installing camshaft 5 Slide camshaft into bearing surface of crankcase positioning timing mark of camshaft gear at 6 o clock position Make su
112. ug lead 1 Disconnect leads from spark plugs 2 Shut off fuel supply Drain Oil From Crankcase and Remove Oil Filter 1 Remove oil fill dipstick and oil drain plug 2 Allow ample time for oil to drain from crankcase and oil filter 3 Remove and appropriately discard oil filter Remove Muffler Remove exhaust system and attaching hardware from engine Remove Fuel Pump if equipped A WARNING Explosive Fuel can cause fires and severe burns CL Do not fill fuel tank while engine is hot or running Gasoline is extremely flammable and its vapors can explode if ignited Store gasoline only in approved containers in well ventilated unoccupied buildings away from sparks or flames Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition Never use gasoline as a cleaning agent 1 Disconnect pulse vacuum hose and outlet fuel line from fuel pump 2 Remove mounting screws unhook outlet hose from blower housing clip and remove fuel pump from blower housing Remove Retractable Starter if equipped Remove mounting screws securing retractable starter to blower housing Remove starter 16 690 01 Rev Disassembly Inspection and Service Remove Blower Housing and Outer Baffles 1 Remove air cleaner cover 2 Remove screws securing blower housing 3 Remove blower housing from engine 4 Remove M5 and M6 screws securing baffles to cylind
113. und oil filter Place a container under filter to catch any oil and remove filter Wipe off mounting surface Reinstall drain plug Torque to 13 6 N m 10 ft Ib Place new filter in shallow pan with open end up Fill with new oil until oil reaches bottom of threads Allow 2 minutes for oil to be absorbed by filter material Apply a thin film of clean oil to rubber gasket on new filter Refer to instructions on oil filter for proper installation Fill crankcase with new oil Level should be at top of indicator on dipstick Reinstall oil fill dipstick and tighten securely Start engine check for oil leaks Stop engine correct leaks Recheck oil level Dispose of used oil and filter in accordance with local ordinances KohlerEngines com 29 Lubrication System OIL SENTRY if equipped NOTE Make sure oil level is checked before each use and is maintained up to FULL or F mark on dipstick This includes engines equipped with Oil Sentry This switch is designed to prevent engine from starting in a low oil or no oil condition Oil Sentry may not shut down a running engine before damage occurs In some applications this switch may activate a warning signal Read your equipment manuals for more information Oil Sentry pressure switch is installed in oil filter adapter Pressure switch is designed to break contact as oil pressure increases above 3 5 psi and make contact as oil pressure decreases below 3 5 psi
114. unning and side clearances See Specifications Replace rod and cap if scored or excessively worn Service replacement connecting rods are available in STD size and 0 25 mm 0 010 in undersize Undersized rods 0 25 mm 0 010 in have an identification marking on lower end of rod shank Always refer to appropriate parts information to ensure correct replacements are used Piston and Rings Inspection Piston and Rings Components and Details A Piston Ring B End Gap C Identification Mark D Piston E Top Compression F Middle Compression Ring Ring G Rails H Expander Scuffing and scoring of pistons and cylinder walls occurs when internal engine temperatures approach welding point of piston Temperatures high enough to do this are created by friction which is usually attributed to improper lubrication and or overheating of engine 16 690 01 Rev Disassembly Inspection and Service Normally very little wear takes place in piston boss piston pin area If original piston and connecting rod can be reused after new rings are installed original pin can also be reused but new piston pin retainers are required A piston pin is included as part of piston assembly if pin boss in piston or pin are worn or damaged a new piston assembly is required Ring failure is usually indicated by excessive oil consumption and blue exhaust smoke When rings fail oil is allowed to enter comb
115. ure with two large head screws and attach ground lead if equipped with a fuel solenoid to original screw location Torque top cover screws to 2 5 3 23 2 6 in Ib Place new spring onto idle speed adjusting screw and install into carburetor Thread in until 3 or 4 threads are exposed as an initial adjustment Reinstall carburetor using appropriate new carburetor and air cleaner base gaskets Reconnect spark plug lead s and negative battery cable Start engine and perform Idle Speed RPM Adjustment For Walbro Carburetors Only 10 11 12 13 14 15 Clean carburetor body jets vent ports seats etc using a good commercially available carburetor solvent Use clean dry compressed air to blow out internal channels and ports Inspect and thoroughly check carburetor for cracks wear or damage Inspect fuel inlet needle seat for wear or damage Check spring loaded choke plate to make sure it moves freely on shaft Clean carburetor float bowl as required Install main nozzle and main jet into tower of carburetor body Install new solenoid gasket on solenoid Reassemble fuel bowl and solenoid Reinstall carburetor using appropriate new carburetor and air cleaner base gaskets Reconnect spark plug lead s and negative battery cable Start engine and perform Idle Speed RPM Adjustment High Altitude Operation Engines may require a high altitude carburetor kit to ensure cor
116. ustion chamber where it is burned along with fuel High oil consumption can also occur when piston ring end gap is incorrect because ring cannot properly conform to cylinder wall under this condition Oil control is also lost when ring gaps are not staggered during installation When cylinder temperatures get too high lacquer and varnish collect on pistons causing rings to stick which results in rapid wear A worn ring usually takes on a shiny or bright appearance Scratches on rings and pistons are caused by abrasive material such as carbon dirt or pieces of hard metal Detonation damage occurs when a portion of fuel charge ignites spontaneously from heat and pressure shortly after ignition This creates 2 flame fronts which meet and explode to create extreme hammering pressures on a specific area of piston Detonation generally occurs from using low octane fuels Pre ignition or ignition of fuel charge before timed spark can cause damage similar to detonation Pre ignition damage is often more severe than detonation damage Pre ignition is caused by a hot spot in combustion chamber such as glowing carbon deposits blocked cooling fins an improperly seated valve or wrong spark plug s Replacement pistons are available in STD bore size and 0 25 mm 0 010 in oversize Replacement pistons include new piston ring sets and new piston pins Replacement ring sets are also available separately for STD and 0 25 mm 0 010 in oversi
117. ywheel Holding Tool CS For holding flywheel of CS series engines SE Tools KLR 82407 Flywheel Puller For properly removing flywheel from engine SE Tools KLR 82408 Flywheel Strap Wrench For holding flywheel during removal SE Tools KLR 82409 16 690 01 Rev KohlerEngines com 13 Tools and Aids TOOLS Description Source Part No Hydraulic Valve Lifter Tool For removing and installing hydraulic lifters Kohler 25 761 38 S Ignition System Tester For testing output on all systems including CD Kohler 25 455 01 S Inductive Tachometer Digital For checking operating speed RPM of an engine Design Technology Inc DTI 110 Offset Wrench K and M Series For removing and reinstalling cylinder barrel retaining nuts Kohler 52 455 04 S Oil Pressure Test Kit For testing verifying oil pressure on pressure lubricated engines Kohler 25 761 06 S Radiator Tester For pressure testing radiator and cap on Aegis liguid cooled engines Kohler 25 455 10 S Rectifier Regulator Tester 120 volt current Rectifier Regulator Tester 240 volt current For testing rectifier regulators Components of 25 761 20 S and 25 761 41 S CS PRO Regulator Test Harness Special Regulator Test Harness with Diode Spark Advance Module SAM Tester For testing SAM ASAM and DSAM on engines with SMART SPARK Starter Servicing Kit All Starters For removing and reinstalling drive r
118. ze pistons Always use new piston rings when installing pistons Never use old rings Some important points to remember when servicing piston rings Piston 1 Cylinder bore must be de glazed before service ring sets are used 2 If cylinder bore does not need re boring and if old piston is within wear limits and free of score or scuff marks old piston may be reused 3 Remove old rings and clean up grooves Never reuse old rings 4 Before installing new rings on piston place top 2 rings each in turn in its running area in cylinder bore and check end gap Top compression ring end gap clearance is 0 189 0 277 mm 0 0074 0 0109 in for a new bore or 0 531 mm 0 0209 in for a used bore Middle compression ring end cap is 1 519 1 797 mm 0 0598 10 0708 in for a new bore or 2 051 mm 0 0808 in for a used bore KohlerEngines com 57 Disassembly Inspection and Service 5 After installing new compression top and middle rings on piston make sure top compression ring to groove side clearance and is 0 030 0 070 mm 0 001 0 0 0026 in and middle compression ring to roove side clearance 0 030 0 070 mm 0 0010 0 026 in If side clearance is greater than specified a new piston must be used Install New Piston Rings NOTE Rings must be installed correctly Ring installation instructions are usually included with new ring sets Follow instructions carefully Use a piston ring expander to install rings Install bottom

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