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1. SERVICE MANUAL ohmmeter leads to terminals Resistance should be 0 41 0 51 ohms for 7E1 models or 1 49 1 82 ohms for 7E3 models Renew stator if desired resistance readings are not obtained OVERHAUL To disassemble generator remove end Model MF 180 MF 260 MAINTENANCE SPARK PLUG Recommended spark plug is a Champion L87Y or NGK BP 6HS Spark plug electrode gap is 0 6 0 7 mm 0 024 0 028 in CARBURETOR MF180 models are equipped with a Mikuni BV18 15 car buretor while MF260 models are equipped with a Keihin BB24 17 carburetor Initial setting of idle mix ture screw is 1 turns on BV18 15 car buretor or 1 turns on BB24 17 carbu retor Refer to following tables for car buretor specifications Mikuni BV18 15 Fuel inletvalv sie seni wewss sanewn 2 0 BERT Fool 600 96 AE 80 FROCAIF JCC sicuiccaesan csansgutees 3 0 PG eb eerren aat 57 5 Keihin BB24 17 Fuel inlet valve 0000s 2 0 Mam MY j tna cease pas elie ein 130 Lg hc re een 85 PGE IOC sie oss ea ace eee news 40 Orewa MILA Fig 2 6 Drawing of governor linkage Re fer to text for operation cover then disconnect and remove con trol box Disconnect and remove brush holder assembly Unbolt and remove mounting cushions from stator housing Unscrew four through bolts securing stator housing and remove stator hous ing Unscrew rotor through bolt then using a slide hammer break rotor loose from crankshaft taper and2. side of Yamaha engine Handle float assembly carefully as reed switch may be damaged if unit is dropped To check operation of float assembly connect an ohmmeter to 218 Fig Y2 22 Generator wiring schematic mounting flange and to wire lead Do not use a continuity tester as battery may damage reed switch Ohmmeter should show continuity with float GENERATOR assembly in normal position and float hanging down Ohmmeter should read infinity with float assembly inverted Oil warning light should be checked Copyright of Small AC Generator Service Manual 3rd Edition is the property of Penton Media Inc Clymer and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder s express written permission However users may print download or email articles for individual use
3. d 0 1 or 2 Note valve lengths in follow ing tables Valve Mark Length ing MF 180 MF260 0 91 70 104 55 91 80 mm 104 65 mm 3 610 4 116 3 614 in 4 120 in l 91 80 104 65 91 90 mm 104 75 mm 3 614 4 120 3 618 in 4 234 in 2 91 90 104 75 92 00 mm 104 85 mm 3 618 4 124 3 622 in 4 128 in Intake valve stem diameter for all models is 6 955 6 970 mm 0 2738 0 2744 in Exhaust valve stem diameter is 6 950 6 970 mm 0 2736 0 2744 in on MF180 models or 6 915 6 930 mm 0 2722 0 2728 in on MF 260 models Valve seat width should be 0 7 0 9 mm 0 027 0 035 in for all valves Valve spring free length is 33 5 mm 1 319 in for MF180 models or 37 0 mm 1 457 in for MF260 models PISTON PIN AND RINGS Piston and connecting rod are removed as a unit after cylinder head and crankcase cover are removed Piston oversizes available are 0 25 mm 0 010 in and 0 05 mm O O 4 CF SS oO Fig Y 2 10 Install head gasket on MF260 models so tab T is towards flywheel side of engine Fig 2 11 Tightening sequence for cylinder head screws GENERATOR 0 020 in Piston clearance should be 0 085 mm 0 0033 in for MF180 models or 0 070 mm 0 0027 in for MF260 models Piston ring end gap should be 0 2 0 4 mm 0 008 0 016 in Install piston so arrow on crown points towards valve side of engine as shown in Fig Y2 12 Piston pin is fully floating ir piston and rod Piston pin r
4. etaining clips should be renewed if removed CONNECTING ROD The connect ing rod and piston are removed as a unit after cylinder head and crankcase cover are removed The aluminum rod rides directly on crankpin Connecting rod to crankpin clearance is 0 016 0 034 mm 0 0006 0 0013 in Connecting rod side clearance is 0 2 0 8 mm 0 008 0 032 in Match marks M Fig Y2 13 must be aligned when installing rod Note that oil dipper on MF260 models is cast into rod cap while oil dipper on MF 180 models is separate and fits between rod cap and lock plate as shown in Fig Y2 14 Tighten rod screws to 11 8 N m 104 in lbs on MF180 models or to 15 7 N m 139 in lbs on MF260 models CAMSHAFT AND GOVERNOR The camshaft rides directly in crankcase and crankcase cover Inspect camshaft lobes gear and bearing surfaces for damage and excessive wear Crankshaft and camshaft timing marks must be aligned as shown in Fig Y2 15 during assembly The governor weights spring and ac tuating collar are mounted on camshaft as shown in Fig Y2 16 Nine governor weights are held by governor spring o1 MF260 models while only four weights are used on MF 180 models Be sure co lar properly engages groove G 12 weights W Install governor fork F Fig Y2 17 on governor shaft S of MF 260 models so pads on fork ends are towards camshaft CRANKSHAFT AND CRANK CASE The crankshaft is supported by ball bearings Inspect crankshaft f
5. in GOVERNOR All models are equipped with a flyweight type governor at tached to and driven by the camshaft gear The governor forces governor shaft S Fig Y2 6 to rotate according to engine speed Pinch bolt B secures governor arm G to shaft S Movement of governor arm G is transmitted by link L to carburetor throttle arm Note in Fig Y2 7 that governor spring end is connected to middle hole H of MF 180 governor arm G or to lower hole H of MF260 governor arm G To adjust governed speed loosen pinch bolt B Fig Y2 6 Pull upper end of governor arm G to left away from carburetor so carburetor throttle is fully open Turn governor shaft S counterclockwise until stop is contacted then retighten pinch bolt B With engine running under no load turn ad justing screw W Fig Y2 7 so max imum governed speed is 3800 rpm If available a frequency meter may be con nected to an outlet and maximum governed speed adjusted so desired cur rent frequency is obtained LUBRICATION Crankcase capacity is 680 ce 0 7 qt on MF 180 models or 950 ce 1 0 qt on MF260 models Use SAE Fig Y2 8 Cross sectional view of oil level warning system 215 Yamaha 30 oil if ambient temperature is above 15 C 60 F SAE 20 if temperature is between 0 C 82 F and 15 C 60 F and SAE 10 if temperature is below 0 C 32 F All models are equipped with a low oil safety system which disables
6. or ex cessive wear straightness and damage Fig 2 12 I nstal piston so arrow on crown points towards valves SERVICE MANUAL Crankpin diameter is 24 952 24 970 mm 0 9824 0 9831 in on MF180 models or 28 952 28 970 mm 1 1398 1 1405 in on MF 260 models Tighten crankcase cover Fig Y2 13 Match marks M on side of rod and cap must be aligned during assembly case cover screws on MF180 fr S fi O O l Ty WE WAY HH fy i x J o4 Fig Y2 14 A separate oil dipper D is used 3 Nm Sk 4 be on MF180 models between rod cap R and 2 A C N Af lock plate L y pit 4 i _ I 1 A WS O S _ _ H Crankshaft case cover screws on MF260 Fig Y 2 15 Align crankshaft and camshaft timing marks K during assembly Fig Y2 20 Exploded view of rewind starter on MF180 Nut Lock washer er Fig 2 16 View of MF180 governor weights si taha handiki W and spring installed on camshaft gear C MF260 assembly is similar but more weights are used Governor collar is not shown but must engage groove G in weights 2 O Ih 7 H Fig 2 21 Exploded view Ce i S of rewind starter on al a ff 76 MF 260 4 i IEE Spring ate Nut Lockwasher A g C i j y Washer Aa paner Faw MY 10 Spring ren 14 Fig Y Y2 17 Install governor fork F on 15 Rewind spring g
7. overnor shaft S of MF260 models with 16 Starter housing pads on fork ends towards camshaft a 9 Beto amp 6 ho M Plate Return spring i 11 Bushing r 13 ee pulley Fig Y 2 18 Tightening sequence for crank Fig Y2 19 Tightening sequence for crank Yamaha screws to 9 8 N m 7 ft Ibs on MF180 models or to 17 N m 12 ft lbs on MF260 models Refer to Fig Y2 18 or Y2 19 for tightening sequence REWIND STARTER Refer to Fig Y2 20 or Y2 21 for an exploded view of rewind starter With starter removed from engine untie rope handle from rope and allow rope to wind into starter housing Unscrew nut 1 to disassemble starter Use care when removing rope pulley 13 so rewind spring 15 is not dislodged from housing 16 If spring 15 must be removed use care as uncon trolled uncoiling of spring may cause in jury When assembling starter install re wind spring 15 so coil direction is counterclockwise from outer end Wind rope on rope pulley in counter clockwise direction as viewed with pulley 13 in stalled in housing 16 Preload rewind spring by turning rope pulley two turns against spring tension before passing rope through rope outlet in housing OIL WARNING SYSTEM All models are equipped with an oil warning system which disables ignition system when low oil level may damage engine See LUBRICATION section To inspect oil level assembly drain engine oil and remove unit from
8. remove ENGINE Cyls Bore Stroke l 65 mm 54 mm 2 559 in 2 126 in 1 73 mm 6 mm 2 874 in 2 402 in IGNITION AND TIMING All models are equipped with a capacitor discharge ignition system The trigger coil and charge coil are attached to a stator plate behind the flywheel while the ignition module is attached to the fan housing Ignition timing is not ad justable To check trigger coil and charge coil remove fan housing disconnect coil leads and remove flywheel Connect an ohmmeter to trigger coil lead and coil base Ohmmeter should read 603 737 ohms if not renew trigger coil Connect ohmmeter to charge coil lead and coil base Ohmmeter should read 342 418 ohms if not renew charge coil When reinstalling flywheel tighten flywheel nut to 54 N m 40 ft lbs on MF180 models or 74 N m 54 ft lbs on MF260 models Note that an erratic or faulty ignition system may be due to an oil warning system malfunction Refer to LUBRICATION section H Fig Y2 7 Adjust governed engine speed as outlined in text Note position of spring end in hole H for MF180 models in View A or for MF260 models in View B Yamaha rotor Inspect components and reassemble generator by reversing disassembly pro cedure Refer to wiring schematic for proper wiring connections Tighten rotor bolt to 18 6 N m 14 ft lbs and stator through bolts to 7 8 N m 6 ft lbs Displ 179 ce 10 9 cu in 206 ce 15 6 cu
9. the ignition system and lights a warning bulb when engine oil level is critically low A float F Fig Y2 8 mounted in the engine crankcase monitors oil level and when the oil level lowers to less than 325 cc 0 34 qt on MF180 models or to less than 450 cc 0 48 qt on MF260 models a magnet in the float closes the contacts in reed switch R thereby grounding the ignition and lighting the oil warning light Refer to OVERHAUL section to ser vice oil warning system OVERHAUL TIGHTENING TORQUES Recom mended tightening torques are as follows Connecting rod MERE EENS 11 8 N m 104 in lbs ME eene ance e 15 7 Nem 139 in lbs Crankease cover MP TRG 3 iscc ace sseere rene 9 8N m 7 ft lbs MPS6D occ cxcivereneeesee 17N m 12 ft lbs Cylinder head ees eomer 19 6 Nem 14 5 ft lbs Flywheel MEIRO ecirar Se DEN Mm 40 ft lbs MEZGO aeriana poraa paa maa 74N m 54 ft lbs CYLINDER HEAD The cylinder head is removable Be sure head gasket is installed as shown in Fig Y2 9 or Y2 10 Tighten cylinder head screws to 19 6 N m 14 5 ft lbs in sequence shown in Fig Y2 11 VALVE SYSTEM Valve tappet gap is 0 05 0 15 mm 0 002 0 006 in on Fig Y2 9 Install head gasket on MF180 models so notch N is towards flywheel side of engine 216 MF180 models or 0 1 0 3 mm 0 004 0 012 in on MF260 models Different length valves are available if valve tap pet gap is incorrect Valves are marke
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