SERVICE MANUAL6BV-28197-3M-11F4BF5AF6CPrefaceThis manual has been prepared by Yamaha primarily for use by Yamaha dealers and their trainedmechanicswhenperformingmaintenanceproceduresandrepairstoYamahaequipment.IthasbeenwrittentosuittheneedsofpersonswhohavetheBronzeTechnicalCertificateoftheYTA(Yamaha Technical Academy) marine or the equivalent basic understanding of the mechanical andelectricalconceptsandproceduresinherentinthework,forwithoutsuchknowledgeattemptedrepairs or service to the equipment could render it unsafe or unfit for use.BecauseYamahahasapolicyofcontinuouslyimprovingitsproducts,modelsmaydifferindetailfromthedescriptionsandillustrationsgiveninthispublication.Useonlythelatesteditionofthismanual.AuthorizedYamahadealersarenotifiedperiodicallyofmodificationsandsignificantchanges in specifications and procedures, and these are incorporated in successive editions of thismanual. Also, up-to-date parts information is available on YPEC-web. Additional information and up-to-date information on Yamaha products and services are available on Yamaha Service Portal.Important informationParticularly important information is distinguished in this manual by the following notations:_ TheSafetyAlertSymbolmeansATTENTION!BECOMEALERT!YOURSAFETYISINVOLVED!A WARNING indicates a hazardous situation which, if not avoided, could result in death orserious injury.ANOTICEindicatesspecialprecautionsthatmustbetakentoavoiddamagestotheout-board motor or other property.TIP:A TIP provides key information to make procedures easier or clearer.F4B, F5A, F6CSERVICE MANUAL2014 by Yamaha Motor Co., Ltd.2nd Edition, September 2014All rights reserved.Any reprinting or unauthorized use without the written permission of Yamaha Motor Co., Ltd. is expressly prohibited.ContentsGeneral informationGENINFO 0SpecificationSPEC1Technical features and descriptionTECHFEA 2Rigging informationRIGGING 3TroubleshootingTRBLSHTG 4Electrical systemELEC5Fuel systemFUEL6Power unitPOWR7Lower unitLOWR8Bracket unitBRKT9MaintenanceMNT10IndexAppendixAGENINFO012345678910AGeneral information 0_Safety while working.................................................... 0-1Rotating part.............................................................................. 0-1Hot part ...................................................................................... 0-1Electric shock............................................................................ 0-1Propeller.................................................................................... 0-1Handling of gasoline.................................................................. 0-1Ventilation .................................................................................. 0-1Self-protection........................................................................... 0-2Working with crane.................................................................... 0-2Part, lubricant, and sealant ........................................................ 0-2Handling of sealant .................................................................... 0-2Special service tool................................................................... 0-2Tightening torque...................................................................... 0-3Non-reusable part ...................................................................... 0-3Disassembly and assembly....................................................... 0-3How to use this manual.................................................... 0-4Manual format........................................................................... 0-4Abbreviation.............................................................................. 0-5Lubricant, sealant, and thread locking agent................. 0-6Symbol...................................................................................... 0-6Special service tool ........................................................... 0-70-1GENINFOGeneral information_Safety while workingTopreventanaccidentorinjuryandtopro-videqualityservice,observethefollowingsafety procedures.Rotating part Hands, feet, hair, jewelry, clothing, personalflotationdevicestraps,andsoon,canbecomeentangledwithinternalrotatingpartsoftheengine,resultinginseriousinjury or death. Keepthetopcowlinginstalledwheneverpossible.Donotremoveorinstallthetopcowling when the engine is running. Only operate the engine with the top cowl-ingremovedaccordingtothespecificinstructionsinthemanual.Keephands,feet,hair,jewelry,clothing,personalflota-tiondevicestraps,andsoon,awayfromany exposed moving parts.Hot partDuringandafteroperation,enginepartsarehot enough to cause burns. Do not touch anypartsunderthetopcowlinguntiltheenginehas cooled.Electric shockDo not touch any electrical parts while start-ing or operating the engine. Otherwise, shockor electrocution could result.PropellerDonotholdthepropellerwithyourhandswhenlooseningortighteningthepropellernut.Handling of gasoline Gasolineishighlyflammable.Keepgaso-lineandallflammableproductsawayfromheat, sparks, and open flames. Gasoline is poisonous and can cause injuryor death. Handle gasoline with care. Neversiphongasolinebymouth.Ifyouswallowsomegasoline,inhalealotofgasolinevapor,orgetsomegasolineinyoureyes,seeyourdoctorimmediately.Ifgasolinespillsonyourskin,washwithsoapandwater.Ifgasolinespillsonyourclothing,change your clothes.Ventilation Gasolinevaporandexhaustgasareheavier than air and extremely poisonous. Ifgasoline vapor or exhaust gas is inhaled inlargequantities,itmaycauselossofcon-sciousness and death within a short time. Whentestrunninganengineindoors(forexample,ina watertank) makesuretodoso where adequate ventilation can be main-tained.0-2_Safety while working012345678910ASelf-protection Protectyoureyesbywearingsafetyglasses or safety goggles during all opera-tions involving drilling and grinding, or whenusing an air compressor. Protect your hands and feet by wearing pro-tectiveglovesandsafetyshoeswhennec-essary.Working with crane Outboard motors weighing 18.0 kg (39.7 lb)and over must be carried by a crane. Usethewireropesofadequatestrength,andliftuptheoutboardmotorusingthethree point suspension. Iftheoutboardmotordoesnothavethreeor more points to be suspended, support itusing additional ropes or the like so that theoutboard motor can be lifted and carried ina stable manner.Part, lubricant, and sealantUseonlygenuineYamahaparts,lubricants,andsealants,orthoserecommendedbyYamaha, when servicing or repairing the out-board motor.Handling of sealant Wear protective gloves to protect your skin,when using the sealants. Seethematerialsafetydatasheetissuedby the manufacturer. Some of the sealantsmay be harmful to human health.Special service toolUsetherecommendedspecialservicetoolsto work safely, and to protect parts from dam-age.0-3GENINFOGeneral informationTightening torqueFollowthetighteningtorquespecificationsprovided throughout the manual. When tight-eningnuts,bolts,andscrews,tightenthelarge sizes first, and tighten fasteners startingin the center and moving outward.Non-reusable partAlways use new gaskets, seals, O-rings, cot-ter pins, and so on, when installing or assem-bling parts.Disassembly and assembly Use compressed air to remove dust and dirtduring disassembly. Applyengineoiltothecontactsurfacesofmoving parts before assembly. Install bearings so that the bearing identifi-cationmarkisfacinginthedirectionindi-catedintheinstallationprocedure.Inaddition,makesuretolubricatethebear-ings liberally. Applyathincoatofwaterresistantgreaseto the lip and periphery of an oil seal beforeinstallation. Checkthatmovingpartsoperatenormallyafter assembly.0-4How to use this manual012345678910AHow to use this manualManual formatThe format of this manual has been designed to make service procedures clear and easy to under-stand. Use the following information as a guide for effective and quality service. Parts are shown and detailed in an exploded diagram and are listed in the component list (see ain the following figure for an example page). The component list consists of part names and quantities, as well as bolt and screw dimensions(see b in the following figure). Symbols are used to indicate important aspects of a procedure, such as the grade of lubricant andthe lubrication points (see c in the following figure). Tightening torque specifications are provided in the exploded diagrams (see d in the following fig-ure),andintherelateddetailedinstructions.Sometorquespecificationsarelistedinstagesastorque figures or angles in degrees. Separateproceduresandillustrationsareusedtoexplainthedetailsofremoval,checking,andinstallation where necessary (see e in the following figure for an example page).TIP:For troubleshooting procedures, see Chapter 4, Troubleshooting.8-1LOWRLower unitLower units k r a m e R y t Q e m a n t r a P . o N2 r e v o C 16 M 1 t l o b t n i o j t f i h S 220 mm1 t n i o J 31 t n i o J 41 w e r c s k c e h C 53 t e k s a G 61 w e r c s g n i h s u l F 72 l e w o D 81 n i p r e t t o C 91 t u n r e l l e p o r P 0 11 r e h s a W 1 11 r e l l e p o r P 2 11 r e c a p S 3 114 Lower case mounting bolt 2 M6 40 mm1 r e h s a w k c o L 5 16 M 1 t l o B 6 120 mm1 e d o n A 7 1A11234238823 222119 195611141418617 151613121110916 Nm (1.6 kgfm, 11.8 ftlb)15Nm (1.5 kgfm, 11.1 ftlb)11Nm (1.1 kgfm, 8.1 ftlb)9 Nm (0.9 kgfm, 6.6 ftlb)9 Nm (0.9 kgfm, 6.6 ftlb)9 Nm (0.9 kgfm, 6.6 ftlb)762011Nm (1.1 kgfm, 8.1 ftlb)AL-transom model8-15LOWRLower unitTIP:While turning the drive shaft clockwise, pushdown on the water pump housing and installwater pump housing.8. Install the plates m and rubber seal n.Checking the lower unit for air leakage1. Install new gaskets a, the drain screw band the flushing screw c.2. Tightenthedrainscrewbandflushingscrew c to the specified torque.3. Install the special service tool d.4. Applythespecifiedpressuretocheckthatthepressureismaintainedinthelowerunitforatleast10seconds.NOTICE:Donotoverpressurizethelowerunit.Otherwise,theoilsealscould be damaged.5. Ifthespecifiedpressurecannotbemaintained,checkthedriveshaft,propeller shaft, and rubber seal for bendsordamage,andchecktheshiftrodrubber seal for damage or wear.Assembling the extension (L-transom model)1. Install the bushing a and circlip b.Drain screw b:9 Nm (0.9 kgfm, 6.6 ftlb)Flushing screw c:9 Nm (0.9 kgfm, 6.6 ftlb)nmmcabaLeakage tester d: 90890-06840Holding pressure:98.0 kPa (0.98 kgf/cm2, 14.2 psi)Driver rod L3 c: 90890-06652Needle bearing attachment d:90890-06615dcdaacdbebc da_Safety while working / How to use this manual0-5GENINFOGeneral informationAbbreviationThe following abbreviations are used in this service manual.Abbreviation DescriptionAPI American Petroleum InstituteBTDC Before Top Dead CenterCCA Cold Cranking AmpereCDI Capacitor Discharge IgnitionEN European Norm (European standard)F ForwardIEC International Electrotechnical CommissionN NeutralOHV Overhead ValvePORT Port sideR ReverseRON Research Octane NumberSTBD Starboard sideTDC Top Dead Center0-6Lubricant, sealant, and thread locking agent012345678910ALubricant, sealant, and thread locking agentSymbolSymbolsinanexplodeddiagramorillustrationindicatethegradeoflubricantandthelubricationpoints.Symbols in an exploded diagram or illustration indicate the type of sealant or thread locking agentand the application points.Symbol Name ApplicationYamaha 4-stroke motor oil LubricantGear oil LubricantWater resistant grease(Yamaha grease A)LubricantMolybdenum disulfide grease LubricantCorrosion resistant grease(Yamaha grease D)LubricantThreeBond 1901 LubricantSymbol Name ApplicationThreeBond 1324 Thread locking agentThreeBond 1401 Thread locking agentGasket Maker SealantLOCTITE 572 (white) SealantHow to use this manual / Lubricant, sealant, and thread locking agent0-7GENINFOGeneral informationSpecial service toolFor all markets except U.S.A. and CanadaSpecial service tools with Yamaha part numbers (90890-*****) are distributed by the Parts Division.Digital circuit tester90890-03174Peak voltage adapter B90890-03172Ignition tester (spark gap tester)90890-06754Vacuum/pressure pump gauge set90890-06756Leakage tester90890-06840Pilot screw driver90890-06673Compression gauge90890-03160Digital tachometer90890-06760Timing light90890-03141Flywheel holder90890-065220-8Special service tool012345678910AFlywheel puller90890-06521Driver rod L390890-06652Needle bearing attachment90890-06615Needle bearing attachment90890-06613Valve spring compressor90890-04019Valve spring compressor attachment90890-06320Valve guide remover/installer90890-06801Valve guide reamer90890-06804Valve lapper90890-04101Valve seat cutter holder90890-063160-9GENINFOGeneral informationValve seat cutter 3090890-06818Valve seat cutter 4590890-06312Valve seat cutter 6090890-06323Valve seat cutter 3090890-06819Valve seat cutter 4590890-06814Valve seat cutter 6090890-06813Needle bearing attachment90890-06612Driver rod LL90890-06605Ball bearing attachment90890-06632Driver rod LS90890-066060-10Special service tool012345678910ABall bearing attachment90890-06655Piston slider90890-06529Stopper guide plate90890-06501Stopper guide stand90890-06538Bearing puller assembly90890-06535Bearing outer race attachment90890-06628Bushing installer center bolt90890-06601Bushing attachment90890-06650Bushing attachment90890-066490-11GENINFOGeneral information MEMO SPEC012345678910ASpecification 1Model feature..................................................................... 1-1General feature......................................................................... 1-1Model designation..................................................................... 1-2Serial number............................................................................ 1-2Model data......................................................................... 1-3Dimension and weight............................................................... 1-3Performance.............................................................................. 1-3Power unit................................................................................. 1-3Lower unit.................................................................................. 1-4Bracket unit............................................................................... 1-4Fuel and oil requirement ............................................................ 1-4Electrical technical data................................................... 1-5Ignition timing control system.................................................... 1-5Charging system (optional for European market) ...................... 1-5Fuel system technical data.............................................. 1-5Fuel system............................................................................... 1-5Power unit technical data................................................. 1-6Power unit................................................................................. 1-6Manual starter........................................................................... 1-6Cylinder head assembly............................................................ 1-7Crankcase assembly................................................................. 1-8Lower unit technical data................................................. 1-9Lower unit assembly .................................................................. 1-9Specified tightening torque ............................................ 1-10Fuel system............................................................................. 1-10Power unit............................................................................... 1-10Lower unit................................................................................ 1-10Bracket unit............................................................................. 1-11General tightening torque.............................................. 1-111-1SPECSpecificationModel featureGeneral featureF4B, F5A, F6C Overall feature 4-stroke, 1-cylinder, OHV, 2-valve, 139.0 cm3 (8.5 cu. in) engine Low emission in compliance with EU regulationsaPower unit Compact OHV engine Blowby gas reburning system Trochoid type oil pump lubrication Decompression starter Fuel line with a primer pump Dual fuel line Recoil manual starterbElectrical Ignition timing control by CDI unit CDI unit with the integrated ignition coil Chargingsystem(optionalforEuropeanmarket)cBracket unit Manual tilt Reverse lock system Balanced carrying handledLower unit Under water exhaust systemabcd1-2Model feature012345678910AModel designationSerial numberTheoutboardmotorserialnumberisindi-catedonalabelaffixedtotheportclampbracket.aModel namebApproved model codecTransom heightdSerial numbereProduction model yeara Model description F: 4-stroke regular rotationb Model name 4: 4/5/6c Product generation B: A and updFunctionsM: Manual startere H: Tiller handlef Transom heightS: S (15 in)L: L (20 in)F 4 B M H Sb a c d e fM B K INDUSTRIE PRODUCT ASSEMBLED IN FRANCE PRODUIT ASSEMBLE EN FRANCEbc adeModel nameApproved model codeStarting serial No.F4BMH 6EC 1000001F5AMH 6ED 1000001F6CMH 6EE 10000011-3SPECSpecificationModel dataDimension and weightPerformancePower unitItem UnitModelF4BMH F5AMH F6CMHOverall length mm (in) 750.0 (29.5)Overall width mm (in) 403.0 (15.9)Overall heightS mm (in) 1040.0 (40.9)L mm (in) 1168.0 (46.0)Boat transom heightS mm (in) 440.0 (17.3)L mm (in) 568.0 (22.4)Weight (with propeller)S kg (lb) 27.0 (59.5)L kg (lb) 28.0 (61.7)Item UnitModelF4BMH F5AMH F6CMHMaximum output At 5000 r/min kW (HP) 2.9 (3.9) At 5500 r/min kW (HP) 3.7 (5.0) 4.4 (6.0)Full throttle operating range r/min 40005000 45005500Engine idle speed r/min 14501550Item UnitModelF4BMH F5AMH F6CMHType 4-stroke, OHVCylinder quantity 1Total displacement cm (cu. in) 139.0 (8.5)Bore stroke mm (in) 62.0 46.0 (2.4 1.8)Compression ratio 8.90 : 1Control system Tiller handleStarting system ManualFuel system CarburetorIgnition control system CDIAdvance type MicrocomputerStarting enrichment Choke valveSpark plug CR6HSB (NGK)Cooling system WaterExhaust system Under waterLubrication system Wet sump1-4Model data012345678910ALower unitBracket unitFuel and oil requirement(*1) If the recommended engine oil grades are not available, use engine oil with an API classificationof SH, SJ, or SL and an SAE classification of 15W-40, 20W-40, or 20W-50.(*2) Meeting both API and SAE requirements.Item UnitModelF4BMH F5AMH F6CMHGear shift positions F-N-RGear ratio 2.08 (27/13)Reduction gear type Straight bevel gearClutch type Dog clutchPropeller shaft type SplinePropeller direction (rear view) ClockwisePropeller markBAItem UnitModelF4BMH F5AMH F6CMHTrim angleAt 12 boat transom Degree 4 to 20Tilt-up angle Degree 64Steering angle Degree 90 + 90Trim and tilt system ManualItem UnitModelF4BMH F5AMH F6CMHFuel type Regular unleaded gasolineFuel minimum rating RON 91Engine oil4-stroke motor oil with combinations of the fol-lowing SAE and API oil classificationsEngine oil grade (*1) API SE, SF, SG, SH, SJ, SLSAE 5W-30, 10W-30, 10W-40Total engine oil quantity (oil pancapacity)L (US qt, Imp qt)0.6 (0.63, 0.53)Gear oil type Hypoid gear oilGear oil grade (*2) API GL-4SAE 90Gear oil quantityL (US qt, Imp qt)0.1 (0.11, 0.09)1-5SPECSpecificationElectrical technical dataIgnition timing control system(*1) The figures are for reference only.Charging system (optional for European market)(*1) The figures are for reference only.Fuel system technical dataFuel systemItem UnitModelF4BMH F5AMH F6CMHSpark plugCap resistance (*1)At 20 C (68 F) kD 5.0Gap mm (in) 0.60.7 (0.0240.028)Ignition timingAt 1500 r/min Degree BTDC 79CDI unitAir gap mm (in) 0.40.6 (0.0160.024)Item UnitModelF4BMH F5AMH F6CMHLighting coilOutput peak voltageAt cranking (unloaded) V 20.0At 1500 r/min (unloaded) V 30.1At 3500 r/min (unloaded) V 64.3Resistance (*1) At 20 C (68 F) D 0.7710.869Rectifier RegulatorOutput peak voltageAt 1500 r/min (loaded) V 13.0At 3500 r/min (loaded) V 13.0Item UnitModelF4BMH F5AMH F6CMHFuel jointHolding pressurePositive pressurekPa (kgf/cm2, psi)50.0 (0.50, 7.3)Fuel strainerHolding pressurePositive pressurekPa (kgf/cm2, psi)200.0 (2.00, 29.0)Primer pumpHolding pressurePositive pressurekPa (kgf/cm2, psi)166.7 (1.667, 24.2)1-6Power unit technical data012345678910A(*1) The figures are for reference only.Power unit technical dataPower unit(*1) Measuring conditions: Ambient temperature 20 C (68 F), wide open throttle, with spark plugremoved from cylinder.Whenpullingthestarterhandletocranktheengine,thecompressionpressuremayvarydepending on the speed at which the starter handle is pulled. The figures are for reference only.Manual starter(*1) The figures are for reference only.CarburetorFloat height (*1) mm (in) 10.0 (0.4)Valve seat size mm (in) 0.8 (0.03)Main jet (MJ) # 60 # 70 # 75Main nozzle mm (in) 1.6 (0.06) 2.0 (0.08) 2.4 (0.09)Pilot jet (PJ) # 35 #42Pilot air jet (PAJ) # 105 # 110Adjustable pilot screw (PS) turns out 1 3/8 3/4 2 1/8 3/4 2 1/4 3/4Fuel pumpHolding pressureInlet positive pressurekPa (kgf/cm2, psi)50.0 (0.50, 7.3)Outlet positive pressurekPa (kgf/cm2, psi)50.0 (0.50, 7.3)Item UnitModelF4BMH F5AMH F6CMHCylinderMinimumcompressionpres-sure (*1)kPa (kgf/cm2, psi)700.0 (7.00, 101.5)ThermostatValve opening temperature C (F) 5862 (136144)Fully open temperature C (F) 70 (158)Fully open stroke mm (in) 3.0 (0.12)Item UnitModelF4BMH F5AMH F6CMHStarter ropeLength (*1) mm (in) 1800.0 (70.9)Extended length mm (in) 1430.01570.0 (56.361.8)Item UnitModelF4BMH F5AMH F6CMHElectrical technical data / Fuel system technical data / Power unit technical data1-7SPECSpecificationCylinder head assembly(*1) The figures are for reference only.Item UnitModelF4BMH F5AMH F6CMHValveClearanceIntake and exhaust mm (in) 0.080.12 (0.0030.005)Margin thickness Intake mm (in) 0.8001.200 (0.03150.0472)Exhaust mm (in) 1.1001.500 (0.04330.0591)Runout (*1)Intake mm (in) 0.050 (0.0020)Exhaust mm (in) 0.030 (0.0012)Seat contact widthIntake and exhaust mm (in) 0.60.8 (0.020.03)Cylinder headWarpage limit 0.10 (0.0039)Push rodRunoutIntake and exhaust mm (in) 0.5 (0.02)Valve springFree length mm (in) 27.6 (1.09)Tilt limit mm (in) 1.0 (0.04)Valve stemDiameterIntake mm (in) 5.4755.490 (0.21560.2161)Exhaust mm (in) 5.4605.475 (0.21500.2156)Runout (*1)Intake mm (in) 0.050 (0.0020)Exhaust mm (in) 0.030 (0.0012)Valve guideInside diameterIntake and exhaust mm (in) 5.5005.512 (0.21650.2170)ClearanceIntake mm (in) 0.0100.037 (0.00040.0015)Exhaust mm (in) 0.0250.052 (0.00100.0020)Installation height mm (in) 8.29.1 (0.320.36)Cam shaftCam lobe heightIntake mm (in) 32.03732.137 (1.26131.2652)Exhaust mm (in) 32.03832.138 (1.26131.2653)Cam lobe widthIntake and exhaust mm (in) 26.95027.050 (1.06101.0650)Fuel pump cam diameter (*1) mm (in) 19.600 (0.7717)Journal diameter mm (in) 14.96514.990 (0.58920.5902)Runout mm (in) 0.030 (0.0012)1-8Power unit technical data012345678910ACrankcase assemblyItem UnitModelF4BMH F5AMH F6CMHCrankcaseCrankshaftjournalinsidediametermm (in) 25.02025.041 (0.98500.9859)Camshaftjournalinsidediametermm (in) 15.00015.018 (0.59060.5913)Oil pumpRotorhousinginsidediame-termm (in) 23.13023.160 (0.91060.9118)Outer rotor diameter mm (in) 22.98023.000 (0.90470.9055)Outer rotor height mm (in) 9.9509.980 (0.39170.3929)Inner rotor height mm (in) 9.9509.980 (0.39170.3929)PistonDiameter mm (in) 61.95061.965 (2.43902.4396)Measuring point mm (in) 1.0 (0.04)Oversize diameter1st mm (in) 62.20062.215 (2.44882.4494)2nd mm (in) 62.45062.465 (2.45872.4592)Piston clearancemm (in) 0.0350.065 (0.00140.0026)Ring groove (Top) mm (in) 1.2101.230 (0.04760.0484)Ring groove (2nd) mm (in) 1.2101.230 (0.04760.0484)Ring groove (Oil) mm (in) 2.0102.030 (0.07910.0799)Pin boss inside diameter mm (in) 15.00415.015 (0.59070.5911)Pin outside diameter mm (in) 14.99515.000 (0.59040.5906)CylinderBore mm (in) 62.00062.015 (2.44092.4415)Piston ringEndgapmeasuringpoint(*1)mm (in) 60.0 (2.36)Top ringType BarrelDimension height (B) mm (in) 1.1701.190 (0.04610.0469)Dimension width (T) mm (in) 2.5002.700 (0.09840.1063)End gap (*1) mm (in) 0.1100.210 (0.00430.0083)Side clearance mm (in) 0.0200.060 (0.00080.0024)2nd ring Type TaperDimension height (B) mm (in) 1.1701.190 (0.04610.0469)Dimension width (T) mm (in) 2.6002.800 (0.10240.1102)End gap (*1) mm (in) 0.2600.410 (0.01020.0161)Side clearance mm (in) 0.0200.060 (0.00080.0024)Oil ringDimension height (B) mm (in) 1.8502.000 (0.07280.0787)Dimension width (T) (*1) mm (in) 2.5502.850 (0.10040.1122)End gap (*1) mm (in) 0.2000.700 (0.00790.0276)Side clearance mm (in) 0.0100.180 (0.00040.0071)1-9SPECSpecification(*1) The figures are for reference only.Lower unit technical dataLower unit assemblyConnecting rodSmall end inside diameter mm (in) 15.01515.029 (0.59110.5917)Big end inside diameter mm (in) 28.00028.015 (1.10241.1030)Oil clearance mm (in) 0.0160.046 (0.00060.0018)CrankshaftRunout mm (in) 0.020 (0.0008)Journaldiameter(cylinderblock side)mm (in) 24.98024.993 (0.98350.9840)Journaldiameter(crankcaseside)mm (in) 24.98224.994 (0.98350.9840)Crankpin diameter mm (in) 27.96927.984 (1.10111.1017)Crankpin width mm (in) 21.00021.100 (0.82680.8307)Valve lifterOutside diameter mm (in) 7.9657.980 (0.31360.3142)Item UnitModelF4BMH F5AMH F6CMHLower unitHolding pressurekPa (kgf/cm2, psi)98.0 (0.98, 14.2)Propeller shaftRunout mm (in) 0.02 (0.001)Drive shaftRunout mm (in) 0.4 (0.02)Item UnitModelF4BMH F5AMH F6CMH1-10Specified tightening torque012345678910ASpecified tightening torqueFuel systemPower unitLower unitPart to be tightened Screw sizeTightening torquesNm kgfm ftlbChoke cable nut 4 0.4 3.0Choke holder bolt M5 4 0.4 3.0Fuel cock screw M6 7 0.7 5.2Intake manifold bolt M6 12 1.2 8.9Throttle cable locknut 4 0.4 3.0Throttle link screw M4 1.5 0.15 1.11Fuel pump valve screw M3 0.5 0.05 0.37Fuel pump screw M4 2 0.2 1.5Fuel pump bolt M6 7 0.7 5.2Part to be tightened Screw sizeTightening torquesNm kgfm ftlbCDI unit bolt M6 10 1.0 7.4Valve adjusting locknut 10 1.0 7.4Drive plate screw 7 0.7 5.2Start-in-gear protection cable locknut 2 0.2 1.5Flywheel magnet nut 60 6.0 44.3Engine shut-off switch nut 2 0.2 1.5Power unit mounting bolt M6 12 1.2 8.9Crankcase bolt1stM65 0.5 3.72nd 11 1.1 8.1Blind plug M8 20 2.0 14.8Pivot bolt 10 1.0 7.4Cylinder head bolt1stM813 1.3 9.62nd 28 2.8 20.7Thermostat cover anode screw M5 2 0.2 1.5Spark plug 13 1.3 9.6Connecting rod cap bolt1stM76 0.6 4.42nd 12 1.2 8.9Breather plate screw M5 8 0.8 5.9Part to be tightened Screw sizeTightening torquesNm kgfm ftlbDrain screw 9 0.9 6.6Flushing screw 9 0.9 6.6Lower case mounting bolt (S-transom model) M6 11 1.1 8.1Lower case mounting bolt (L-transom model) M6 15 1.5 11.1Shift joint bolt M6 16 1.6 11.8Check screw 9 0.9 6.6Power unit technical data / Lower unit technical data / Specified tightening torque1-11SPECSpecificationBracket unitGeneral tightening torqueThis chart indicates the tightening torques forstandardfastenerswithastandardISOthread pitch. Tightening torque specificationsforspecialcomponentsandassembliesareprovidedintheapplicablesectionsofthismanual.Topreventwarpage,tightenmulti-fastenerassembliesinacrisscrossfashionandprogressivestagesuntilthespecifiedtorqueisreached.Unlessotherwiseindi-cated,torquespecificationsrequireclean,dry threads.Components should be at room temperature.Part to be tightened Screw sizeTightening torquesNm kgfm ftlbThrottle rod screw M5 4 0.4 3.0Throttle grip screw M5 4 0.4 3.0Tiller handle mounting bolt M8 28 2.8 20.7Carrying handle bolt M8 19 1.9 14.0Start-in-gear protection cable locknut 4 0.4 3.0Primer pump holder bolt M6 11 1.1 8.1Shift lever bolt M8 19 1.9 14.0Shift link bolt M5 3.5 0.35 2.58Grease nipple 3 0.3 2.2Self-locking nut 15 1.5 11.1Width across flats (A)Screw size (B)General torque specificationsNm kgfm ftlb8 mm10 mm12 mm14 mm17 mmM5M6M8M10M12581836430.50.81.83.64.33.75.913.326.631.7TECHFEA012345678910ATechnical features and description 2Engine control system ...................................................... 2-1Outline....................................................................................... 2-1CDI unit..................................................................................... 2-2Ignition timing control................................................................ 2-2Ignition cut-off control................................................................ 2-3Power unit system............................................................ 2-4Outline....................................................................................... 2-4Automatic decompressor ........................................................... 2-5Blowby gas reburning system................................................... 2-6Lighting coil (optional for European market) .............................. 2-7Fuel system....................................................................... 2-8Outline....................................................................................... 2-8Carburetor................................................................................. 2-9Built-in primer pump................................................................ 2-12Lubrication system......................................................... 2-13Outline..................................................................................... 2-13Oil pump and engine oil flow................................................... 2-13Tilt system....................................................................... 2-14Outline..................................................................................... 2-14Reverse lock system............................................................... 2-14Lubrication diagram ........................................................ 2-15Cooling flow diagram ...................................................... 2-16Intake and exhaust flow diagram ................................... 2-172-1TECHFEA Technical features and descriptionEngine control systemOutlineThe F4B, F5A, F6C adopt the CDI ignition system consisting of the CDI unit and a permanent mag-net of the flywheel magnet.The CDI unit has a compact design with an integrated ignition coil.There are two types of ignition control systems. One is ignition timing control at normal operation,and the other one is ignition cut-off control during engine cranking and when over-revving.aCDI unitbFlywheel magnetaPermanent magnetaab2-2Engine control system012345678910ACDI unitWhen the permanent magnet a on the flywheel magnet a passes in front of the CDI unit b, theexciter coil b in the CDI unit b induces an electric current c to produce a crank signal d that willbetransmittedtotheignitioncontrolcircuite.Theelectriccurrentthathasbeeninducedbytheexciter coil b is also sent to charge the capacitor f.When the ignition control circuit e transmits an ignition signal g, the capacitor f will discharge andproduce current h in the primary coil k, and induce a high voltage m in the secondary coil n toignite the spark plug c.The CDI unit b ignites the spark plug c once per crankshaft rotation.Ignition timing controlTheCDIunitignitesthesparkplugattheignitiontimingsthatareprogrammedbasedoneachengine speed. The engine speed will be calculated based on the crank signals that are input into the ignition con-trol circuit.adcbbegfk nch ma2-3TECHFEA Technical features and descriptionIgnition cut-off controlThere are two types of ignition cut-off control. One is a system to cut off the ignition during enginecranking without outputting ignition signals a from ignition control circuit b when the engine speedis 150 r/min or lower. The other one is a system to stop ignition to prevent damage to the enginewhen over-revving. While this control system is activated, the ignition control circuit b keeps output-ting ignition signals a without charging the capacitor c.A Ignition control during engine crankingB Engine speed controlIgnition control during engine cranking Engine speed control150 r/min or less 5900 r/min or morebacAbcBa2-4Power unit system012345678910APower unit systemOutlineThe F4B, F5A, F6C feature an OHV engine with a newly designed cylinder head and cylinder block. The decompressor is built into the camshaft to facilitate engine cranking with a manual starter. In addition, a blowby gas reburning system is incorporated to reduce the amount of oil contained inthe blowby gases.Theflywheelmagnet,lightingcoil,andRectifierRegulatorareavailableasoptionalaccessories,and these will enable battery charging. (Optional for European market)aValve lifterbPush rodcRocker armdValveeRectifier Regulator (optional)fLighting coil (optional)gFlywheel magnet (optional)hIntake silenceraDecompression actuatorcdb aaefghEngine control system / Power unit system2-5TECHFEA Technical features and descriptionAutomatic decompressorTo facilitate engine cranking, the decompression actuator forcefully opens the exhaust valve on thecompression stroke to release compression pressure during engine cranking and prevent pressurein the cylinder from increasing. As the cranking speed increases, the decompression actuator willmove in the direction of a due to the centrifugal force and the exhaust valve will return to normaloperation.A Compression pressureaADecompression actuator2-6Power unit system012345678910ABlowby gas reburning systemA blowby gas reburning system is adopted to be respectful with the environment.To reburn the blowby gases, this engine separates oil from the blowby gases in two labyrinths.First, oil is separated from the blowby gases in the cylinder block labyrinth, and then in the intakesilencer labyrinth.The oil separated from the blowby gases flows back to the crankcase, and the blowby gases sepa-rated from the oil are sucked into the combustion chamber.aCylinder block labyrinthbIntake silencer labyrinthA Blowby gasB Engine oilC AirBCAba2-7TECHFEA Technical features and descriptionLighting coil (optional for European market)The F4B, F5A, F6C can be equipped with a flywheel magnet, lighting coil, and Rectifier Regulator,available as optional accessories, to enable battery charging.The electrical current generating capacity is 6A when the engine speed is at 6000 r/min.aLighting coilbRectifier RegulatorcFusedBatteryeSwitchfElectrical componentabcdef2-8Fuel system012345678910AFuel systemOutlineThisengineisequippedwithasimply-designedandreliablebutterfly-typecarburetor.Abuilt-inprimer pump is also provided in order to ease engine starting when the float chamber is empty, orwhen operating the engine after it has been stored for a long time.aPrimer pumpbCarburetorbaPower unit system / Fuel system2-9TECHFEA Technical features and descriptionCarburetorIdle and low speed operationWhen the engine is running at idle or at low speed, negative pressure generated in the pilot passagea will be increased.Air is drawn into the pilot passage through the pilot air jet b to be mixed with the fuel that is alsosucked into the passage through the pilot jet a. This air and fuel mixture is supplied to the enginethrough the pilot hole c. The pilot screw b controls the amount of air and fuel mixture that will besupplied to the engine.When running at low speed, the air and fuel mixture is supplied to the engine through the pilot holec and through the bypass holes d.A Idle operationB Low speed operationC AirD FuelE Air and fuel mixtureABbaacbacdbbCDE2-10Fuel system012345678910AMedium speed operationWhenrunningatmediumspeed,theairthathasenteredthroughthemainboreaflowsfaster,causing negative pressure to increase in the main bore a.When the negative pressure in the main bore a increases, the fuel is sucked from the main jet a tobe mixed with the air that has entered from the main air jet b through the emulsion tubec, andthen drawn into the main nozzle b.The fuel drawn into the main nozzle b is mixed with the air in the venturi, producing air and fuel mix-ture that will be supplied to the engine.The air and fuel mixture is simultaneously supplied to the engine through the pilot hole d and thebypass holes e.A AirB FuelC Air and fuel mixtureABCedbcaba2-11TECHFEA Technical features and descriptionHigh speed operationWhen running at high speed, the throttle valve opening is near the fully open position, and the neg-ative pressure generated in the main bore a becomes even higher. Consequently, a larger amountof air and fuel mixture is drawn from the main nozzle a to be supplied to the engine.At high speed operation, as the negative pressure in the main bore a becomes higher than the neg-ative pressure in the pilot passage b, fuel is not drawn through the pilot jet c.A AirB FuelC Air and fuel mixtureABCcaba2-12Fuel system012345678910ABuilt-in primer pumpThis engine is equipped with a built-in primer pump in order to ease engine starting when the floatchamber is empty, or when operating the engine after it has been stored for a long time.The built-in primer pump sends fuel directly to the float chamber in the carburetor without operatingthe mechanical fuel pump.A Fuel passage (mechanical fuel pump)B Fuel passage (built-in primer pump)AB2-13TECHFEA Technical features and descriptionLubrication systemOutlineFor the first time in a single-cylinder engine, a trochoid type oil pump has been adopted in order toimprove lubrication performance.The oil hole in the crankshaft allows oil to lubricate the crankpin and connecting rod.Oil pump and engine oil flowThe oil pump is driven by the camshaft.The oil that has been pumped out by the oil pump flows into the camshaft, and it is then sent to theupper part of the engine to lubricate the crankshaft journal bearing. After that, the oil flows down to the crankshaft, and then it is splashed by the rotational force of thecrankshaft to lubricate all parts of the engine.There is an oil hole in the crankshaft.The oil entered through the oil hole will flow down to the crankpin to lubricate the crankpin and con-necting rod.aOil pumpbCamshaftcCrankshaft journal bearingdCrankshaftaOil holebCrankpinA Engine oil flowB Splashing oilABacdabb2-14Tilt system012345678910ATilt systemOutlineTheincorporatedreverselocksystempreventstheoutboardmotorfromtiltingupwhentheshiftposition is in reverse and the throttle is applied.Reverse lock systemIn this system, the tilt up function will be automatically locked when shifted in reverse. When the shiftleveraismovedtothereverseposition,therodb,whichwaspushingupthereverselockc,moves down. Then, due to the return spring d force, the reverse lockc is forced to move in thedirection a to prevent the outboard motor from tilting up.The reverse lock system does not operate when the outboard motor is tilted up.acabdLubrication system / Tilt system2-15TECHFEA Technical features and descriptionLubrication diagramA Engine oil flowB Splashing oilBACrankshaftCrankshaftjournal bearingCamshaftOil pumpOil strainerCylinder headCamshaftPistonCylinder boreValve lifterCrankshaftCrankshaftjournal bearingCylinder blockCamshaftOil pumpOil strainerCrank caseCrankpin2-16Cooling flow diagram012345678910ACooling flow diagramA Cooling water flowB Pilot waterBAThermostatUpper caseCooling water hoseWater pumpCooling water inletThermostatCylinder headCylinder blockUpper caseWater pumpCooling water inletCooling water hoseUpper caseLower caseWaterLubrication diagram / Cooling flow diagram2-17TECHFEA Technical features and descriptionIntake and exhaust flow diagramA Intake air flowB Exhaust gas flowBAIntake manifoldCarburetorIntake silencerRIGGING012345678910ARigging information 3Outboard motor installation............................................. 3-1Dimension.......................................................................... 3-2Exterior F4BMH, F5AMH, F6CMH............................................ 3-2Clamp bracket........................................................................... 3-3Uncrating procedure......................................................... 3-4Outboard motor mounting ................................................ 3-4Installing the charging system (optional for European market). 3-5Installing the battery (optional for European market)................ 3-6Rigging recommendations............................................... 3-7Battery requirement................................................................... 3-7Propeller selection............................................................ 3-7Propeller size ............................................................................. 3-7Selection .................................................................................... 3-73-1RIGGINGRigging informationOutboard motor installation Overpowering a boat could cause severe instability. Do not mount an outboard motor withmorehorsepowerthanthemaximumratingonthecapacityplateoftheboat.Iftheboatdoes not have a capacity plate, consult the boat manufacturer. Impropermountingoftheoutboardmotorcouldresultinhazardousconditions,suchaspoorhandling,lossofcontrol,orfirehazards.ConsultyourdealerorhaveaYamaha-trained person experienced in proper rigging mount the outboard motor.Toomuchweightonthetransomcouldchangethecenterofgravity,buoyancy,operatingbalance, or performance of the boat, which could cause loss of control or swamping. Con-sult the boat manufacturer for the maximum engine weight allowable on the transom, whichis different from the overall boat capacity. Overloading the transom with an outboard motorthat is too heavy could also damage the hull, transom, deck, or helm area, as well as the out-board motor and other equipment. 3-2Dimension012345678910ADimensionExterior F4BMH, F5AMH, F6CMH(*1) Transom height906912425 (16.8)325 (12.8)222 (8.8)181 (7.2)153 (6.1)134 (5.3)383 (15.1)63 (2.5)259 (10.2)341 (13.5)409 (16.2) 130 (5.2)L: 562 (22.2)S: 435 (17.2)L: 93 (3.7)S: 71 (2.8)L: 637 (25.1)S: 555 (21.9)L: 771 (30.4)S: 644 (25.4)503 (19.9)191 (7.6)395 (15.6)430 (17.0)39 (1.6)104 (4.1)0.6 (0.02)S: 635 (25.0)L: 753 (29.0)(*1)mm (in)Outboard motor installation / Dimension3-3RIGGINGRigging informationClamp bracket22 (0.9)60 (2.4)83 (3.3)136 (5.4)48 (1.9)83 (3.3)55 (2.2) 55 (2.2)mm (in)3-4Uncrating procedure012345678910AUncrating procedure1. Checkthecrateforanyshippingdam-age.2. Open the top cover.3. Removethewrapping,andthenchecktheoutboardmotorforconcealeddamage.4. Passtheliftingropearoundthecarryinghandle.NOTICE: Donotusealiftingharness to lift up the outboard motor.5. Tension the lifting rope.6. Liftuptheoutboardmotorcarefullysothat the carrying handle is facing up.7. Place the outboard motor on the boat oron a stand.TIP:Place the outboard motor on the boat or on astandsothattheclampbracketisinthetilt-up position for easy mounting.Outboard motor mountingPropermountingoftheoutboardmotorwillprovidebetterperformance,maximumreli-ability,andhighestcustomersatisfaction.This chapter contains the specifications nec-essary to mount the outboard motor, and mayvary slightly depending on applications.Whenmountingtheoutboardmotor,makesurethatthereissufficientclearancefortheoutboard motor to fully move to port and star-board, as well as fully tilt up. See Dimension(3-2).1. Place the outboard motor on the verticalcenterlineoftheboattransom.Checkthatdistanceaisequaltodistanceband that distance c is equal to distanced.A Hull without strakesB Hull with strakesC/L: Centerline of transoma bc dC/LAa bc dC/LBDimension / Uncrating procedure / Outboard motor mounting3-5RIGGINGRigging information2. Adjust the position of the outboard motorsothattheheightoftheanti-cavitationplateeisbetweenthebottomoftheboat and a maximum of 25.0 mm (1.0 in)f below it.TIP:This mounting height information is for refer-enceonly.Itisimpossibletoprovidecom-plete instructions for every possible boat andoutboard motor combination.3. Tighten the clamp screws.Installing the charging system (optional for European market)1. Drainanyremainingfuelfromthefueltank.2. Removethemanualstarter.SeeRemoving the manual starter (7-7).3. Removetheflywheelmagnet.SeeRemoving the flywheel magnet (7-19).4. Slidetheclampadown,andthendisconnect the fuel hose b.5. Remove the fuel tank c.6. Install the lighting coil d.7. Removethebolte,andtheninstalltheRectifier Regulator f using the includedbolts g.8. Remove the grommet h, and then routethe leads i.9. Installtheholderjusingthefueljointboltk,andthenfastentheleadsusingthe holder j.10. Connect the connector a of leads i.efacbdgfehajikj3-6Outboard motor mounting012345678910A11. Installthebracketltothebottomcowlingusingtheself-tappingboltm,and then install the fuse box n.12. ConnecttheRectifierRegulatorconnectorsofGreen(G)leadsandRed(R) lead.13. Removethebolto,andtheninstalltheRectifierRegulatorgroundleadb,fuseground lead c, and bracket p using theremoved bolt o.14. Install the holder q, and then fasten theleads using the holder q.TIP:Checkthatthelightingcoilleadsddonotinterfere with the flywheel magnet.15. Installtheincludedflywheelmagnet(optional).SeeInstallingtheflywheelmagnet (7-19).16. Connectthehoseb,andthenfastenitusing the clamp a.17. Install the fuel tank c.18. Install the manual starter. See Installingthe manual starter (7-10).Installing the battery (optional for European market)Improperbatteryconnectionsorcablesize selection may result in a fire.If battery connections are reversed, checktheelectricalsystemandreplaceanydamaged components.lmnGRpbcoq dbac3-7RIGGINGRigging informationRigging recommendationsBattery requirementMakesurethatthesizeofthebatterycableterminalsisappropriateforthesizeofthebattery terminals.To prevent the battery cable terminal connec-tionsfromcorroding,soldereachbatterycable terminal to the battery cable.Propeller selectionTheperformanceofaboatandoutboardmotorwillbecriticallyaffectedbythesizeand type of propeller that is used. Propellersgreatlyaffectboatspeed,acceleration,enginelife,fueleconomy,andevenboatingand steering capabilities. An incorrect choicecould adversely affect performance and couldalso seriously damage the engine. Usethefollowinginformationasaguideforselecting a propeller that meets the operatingconditions of the boat and outboard motor.Propeller sizeThesizeofthepropellerisindicatedonapropeller blade.aPropeller diameter (in inches)bPropeller pitch (in inches)cPropeller type (propeller mark)SelectionWhentheenginespeedisatthefullthrottleoperatingrange,theidealpropellerfortheboatisonethatprovidesmaximumperfor-mance in relation to boat speed and fuel con-sumption.(*1) For European market(*2) F6C onlyAmbient temperature above 0 C (32 F)Unit Minimum capacityCCA/EN 347.0 Amps20HR/IEC 40.0 Aha bcFull throttle operating range: F4B: 40005000 r/minF5A, F6C: 45005500 r/minPropeller size (in) Material7 1/2 8 - BAAluminum 7 1/4 6 1/2 - BA (*1)7 1/4 8 1/4 - BA (*2)TRBLSHTG012345678910ATroubleshooting 4Outboard motor troubleshooting ..................................... 4-1Troubleshooting procedure....................................................... 4-1Troubleshooting the power unit................................................. 4-1Troubleshooting the lower unit.................................................. 4-34-1TRBLSHTGTroubleshootingOutboard motor troubleshootingTroubleshooting procedure1. Before troubleshooting the outboard motor, make sure that fresh fuel of the specified type hasbeen used.2. Make sure that all electrical connections are secure and free from corrosion.3. Iftheoutboardmotorisequippedwiththechargingsystem(optionalforEuropeanmarket),check that the battery is fully charged.Troubleshooting the power unitTroubleshooting consists of the following 3 items:Symptom 1: Specific trouble conditionsSymptom 2: Trouble conditions of an area or individual partCause: Trouble causes of symptom 2 : Not applicableSymptom 1: Engine does not crank.Symptom 1: Engine will not start (engine cranks).Symptom 2 Cause Checking stepSee pageStarter handle cannot be pulledGear shift not in the N position Set the gear shift to the N position. 10-4Start-in-gear protection cable not adjusted properlyAdjust the start-in-gear protection cable.7-10Manual starter malfunction Disassemble and check the manual starter.7-7Decompressor malfunction Check the camshaft. 7-44Stuck piston or crankshaft Disassemble and check the power unit. 7-217-39Stuck drive shaft Disassemble and check the lower unit. 8-78-10Starter handle can be pulled, but the engine does not crankManual starter malfunction Disassemble and check the manual starter.7-7Damaged flywheel magnet Woodruff keyCheck the flywheel magnet Woodruff key.7-18Symptom 2 Cause Checking stepSee pageSpark plug does not spark Check the ignition spark. 5-5Spark plug malfunction Check the spark plug. 7-35Spark plug cap malfunction Check the spark plug cap. 5-5Engine shut-off switch malfunc-tionCheck the engine shut-off switch.5-6Fuel not supplied Fuel cock closed Set the fuel cock to the proper position. Clogged fuel strainer Check the fuel strainer for clog or dirt. 6-6Fuel leakage Check the fuel line for fuel leakage. 6-1Fuel pump malfunction Check the fuel pump for fuel leakage. 6-22Check the diaphragm for tears. 6-23Check the camshaft for wear. 7-44Carburetor malfunction Disassemble and clean the carburetor. 6-184-2Outboard motor troubleshooting012345678910ASymptom 1: Unstable engine idle speed, poor acceleration, poor performance, limited enginespeed, or engine stalls.Symptom 1: High engine idle speed.Symptom 1: Engine overheats.Compression pressure is lowCompression leakage Measure the compression pressure. 7-1Check the valve for bends or stuck. 7-27Check the decompressor for proper operation.7-44Check the piston and piston ring for damage.7-41Check the cylinder for damage. 7-41Improper valve timing Check the valve timing. 7-37Symptom 2 Cause Checking stepSee pageFuel not supplied Check that the air vent screw is open. Throttle valve does not move properlyCarburetor malfunction Check the throttle valve for proper move-ment.6-18Throttle link and throttle cable not installed properlyAdjust the throttle link and throttle cable.6-14Spark is weak Check the CDI unit air gap. 7-1Improper fuel and air amount suppliedChoke valve does not operate properlyCheck the choke valve operation.Carburetor malfunction Adjust the pilot screw. 6-19Disassemble and clean the carburetor. 6-18Air leakage (carburetor to cylin-der head)Check the O-ring and gaskets of the car-buretor and intake manifold.6-10Symptom 2 Cause Checking stepSee pageImproper fuel and air amount suppliedCarburetor malfunction Adjust the pilot screw. 6-19Disassemble and clean the carburetor. 6-18Throttle link and throttle cable not installed properlyAdjust the throttle link and throttle cable.6-14Symptom 2 Cause Checking stepSee pageCooling water not dis-charged from the cooling water pilot holeClogged cooling water inlet Check the cooling water inlet. 10-7Water pump impeller malfunc-tionCheck the impeller. 8-6Check the pin. 8-6Water leakage from the water pump housingCheck the insert cartridge. 8-6Check the outer plate cartridge. 8-6Check the water pump housing. 8-6Leak or clogged cooling water passageCheck the water pipe for damage and proper installation.9-9Check the cooling water passage. 2-16 Thermostat malfunction Check the thermostat. 7-35Symptom 2 Cause Checking stepSee page4-3TRBLSHTGTroubleshootingSymptom 1: Improper oil lubrication.Symptom 1: Discharged battery (optional for European market).Troubleshooting the lower unitTroubleshooting consists of the following 3 items:Symptom 1: Specific trouble conditionsSymptom 2: Trouble conditions of an area or individual partCause: Trouble causes of symptom 2 : Not applicableSymptom 1: Shift mechanism of the forward gear and reverse gear does not operate prop-erly.Symptom 2 Cause Checking stepSee pageOil cannot be seen through the oil lubrica-tion check windowLow engine oil level Check the oil level. 10-3Check for engine oil leakage. 2-13Check the valve stem seal and valve. 7-27Check the piston ring. 7-41Insufficient oil lubrication Check the oil pump. 7-23Check the oil strainer. 7-25Check the oil passage. 2-13Symptom 2 Cause Checking stepSee pageBattery performance decrease Check the battery capacity and specific gravity.Short, open, or loose connec-tion in charging circuitCheck the battery cable and terminals for proper connections.Lighting coil malfunction Measure the lighting coil output peak voltage.5-4Measure the lighting coil resistance. 5-4Rectifier Regulator malfunction Measure the Rectifier Regulator output peak voltage.5-4Check the Rectifier Regulator for conti-nuity.5-4Symptom 2 Cause Checking stepSee pageShift rod malfunction Check the shift rod joint.8-16Shift mechanism malfunction (lower unit)Check the shift rod for wear. 8-6Check the dog clutch. 8-9Check the forward gear, reverse gear, and pinion for damage or wear.8-98-118-11ELEC012345678910AElectrical system 5Electrical component and wiring harness routing ......... 5-1Port ........................................................................................... 5-1Top............................................................................................ 5-2Checking the electrical component ................................. 5-3Measuring the peak voltage...................................................... 5-3Using the digital tester............................................................... 5-3Charging unit and component......................................... 5-4Checking the lighting coil (optional for European market)......... 5-4Checking the Rectifier Regulator (optional for European market) .................................................. 5-4Ignition unit and component............................................ 5-5Checking the ignition spark....................................................... 5-5Checking the spark plug cap..................................................... 5-5Checking the engine shut-off switch .......................................... 5-65-1ELECElectrical systemElectrical component and wiring harness routingPort aEngine shut-off switch lead (Black)bSpark plug capcSpark plugdGround lead (Black)eCDI unit lead (Black)fRectifier Regulator (optional for European market)A Install the holder horizontally, and then fasten the spark plug wire using the holder. B Point the end of plastic tie inward (engine side), and then cut the end.bc fA Bad e d5-2Electrical component and wiring harness routing012345678910ATopaEngine shut-off switchbCDI unitcFuse (20 A) (optional for European mar-ket)dLighting coil (optional for European mar-ket)A Fold the holders inward so that the leads do not come out from the holders.B Check that the ground lead does not inter-fere with the bolt or washer.cbBaAd5-3ELECElectrical systemChecking the electrical componentMeasuring the peak voltageWhen measuring the peak voltage, do nottouch any of the connections of the digitaltester probes.Whenmeasuringthepeakvoltagebetweentheterminalsofanelectricalcomponentusingthedigitaltester,makesurethattheleadsdonotcontactanymetal parts. Otherwise, the electrical com-ponentmayshort-circuitandbedam-aged.Tochecktheelectricalcomponentsormea-surethepeakvoltage,usethespecialser-vicetools.Amalfunctioningelectricalcomponentcanbecheckedeasilybymea-suring the peak voltage. The specified enginespeedwhenmeasuringthepeakvoltageisaffectedbymanyfactors,suchasfouledspark plugs or a weak battery. If one of thesefactors is present, the peak voltage cannot bemeasured properly.TIP: Beforemeasuringthepeakvoltage,checkall wiring harness for corrosion. Also, makesurethatthewiringharnessisconnectedproperlyandthatthebatteryisfullycharged. UsepeakvoltageadapterBwiththerec-ommended digital circuit tester. Connectthepositivepinofpeakvoltageadapter B to the positive terminal of the dig-ital circuit tester, and the negative pin to thenegative terminal. Whenmeasuringthepeak voltage,setthedigitalcircuittestertotheDCvoltagemode.Using the digital testerTheelectricaltechnicaldataapplytothemeasurementstakenusingtheYamaha-rec-ommended tester.Theresistancevaluesshownarethevaluestaken before the engine is started. The actualresistancemayvarydependingontheenvi-ronmentalconditionsandambienttempera-ture.Digital circuit tester: 90890-03174Peak voltage adapter B: 90890-03172DC V5-4Charging unit and component012345678910ACharging unit and componentChecking the lighting coil (optional for European market)1. Removetheholdera,andthendiscon-nect the lighting coil connectors a.2. Measurethelightingcoiloutputpeakvoltage.TIP:Topreventtheenginefromstartingwhencrankingit,removetheclipfromtheengineshut-off switch.3. Measure the lighting coil resistance.4. Connect the lighting coil connectors, andthenfastenthelightingcoilleadsusingthe holder a.Checking the Rectifier Regulator (optional for European market)Ifthebatterycablesareconnectedinreverse,theRectifierRegulatorcanbedamaged.1. Remove the holder a.2. MeasuretheRectifierRegulatoroutputpeak voltage.TIP:DonotusepeakvoltageadapterBwhenmeasuringtheRectifierRegulatoroutputpeak voltage.3. DisconnecttheRectifierRegulatorconnectorsa,b,c,andRectifierRegulator ground lead d.4. ChecktheRectifierRegulatorforcontinuity. Replace if out of specification.Lighting coil output peak voltage:Green (G)Green (G)r/minUnloadedCranking 1500 3500DC V 20.0 30.1 64.3Lighting coil resistance (reference data):0.7710.869 D at 20 C (68 F)G GaaRectifier Regulator peak voltage:Red (R)Groundr/minLoaded1500 3500DC V 13.0 13.0RRaRabc ddcbaChecking the electrical component / Charging unit and component5-5ELECElectrical systemOL: Indicates an overloadTIP:Make sure to set the tester measurementrange to the diode mode.5. ConnecttheRectifierRegulatorconnectorsa,b,c,andRectifierRegulator ground lead d.6. FastentheRectifierRegulatorleadsusing the holder a.Ignition unit and componentChecking the ignition spark1. Disconnectthesparkplugcapfromthespark plug.2. Connect the spark plug cap to the specialservice tool a.3. Crank the engine and check for a spark.WARNING!Donottouchanyoftheconnectionsofthespecialservicetool.4. Disconnectthespecialservicetoola,and then connect the spark plug cap.Checking the spark plug cap1. Removethesparkplugcapfromthespark plug wire by turning the cap coun-terclockwise.2. Measure the spark plug cap resistance.Rectifier Regulator continuity(testing diode mode):Tester probeDisplay value(reference data) ab OLc OLd OLba 0.384 Vc 0.938 Vd 0.649 Vca 0.384 Vb 0.938 Vd 0.654 Vda 0.716 Vb 0.384 Vc 0.384 VabcdIgnition tester (spark gap tester) a:90890-06754Spark plug cap resistance(reference data):5.0 kD at 20 C (68 F)OKa5-6Ignition unit and component012345678910A3. Installthesparkplugcaptothesparkplugwirebyturningthesparkplugcapclockwise.Checking the engine shut-off switch1. Disconnecttheengineshut-offswitchconnector a.2. Checktheengineshut-offswitchforcontinuity.3. Connecttheengineshut-offswitchconnector a.Switch positionTerminalb cClip installedClip removed O OButton pushed O OacbCharging unit and component / Ignition unit and component5-7ELECElectrical system MEMO FUEL012345678910AFuel system 6Hose routing...................................................................... 6-1Fuel hose ................................................................................... 6-1Blowby hose, oil return hose, and cooling water hose.............. 6-2Fuel tank............................................................................ 6-3Removing the fuel tank .............................................................. 6-5Removing the primer pump....................................................... 6-5Checking the fuel tank............................................................... 6-6Checking the fuel joint............................................................... 6-6Checking the fuel strainer (tank side)........................................ 6-6Checking the fuel strainer .......................................................... 6-6Checking the primer pump........................................................ 6-7Installing the primer pump......................................................... 6-7Installing the fuel tank ................................................................ 6-8Intake silencer................................................................. 6-10Removing the throttle cable and throttle link........................... 6-12Removing the carburetor......................................................... 6-12Installing the carburetor........................................................... 6-13Installing the throttle cable and throttle link............................. 6-13Adjusting the throttle cable and throttle link ............................. 6-14Carburetor ........................................................................ 6-16Disassembling the carburetor .................................................. 6-18Checking the carburetor.......................................................... 6-18Assembling the carburetor...................................................... 6-19Fuel pump........................................................................ 6-21Removing the fuel pump......................................................... 6-22Checking the fuel pump ........................................................... 6-22Disassembling the fuel pump.................................................. 6-22Checking the diaphragm and valve......................................... 6-23Assembling the fuel pump....................................................... 6-23Installing the fuel pump........................................................... 6-246-1FUELFuel systemHose routingFuel hoseaFuel hose (fuel tank to fuel cock)bFuel hose (fuel cock to fuel strainer)cFuel hose (fuel strainer to joint)dFuel hose (joint to fuel pump)eFuel hose (fuel pump to carburetor)fFuel hose (joint to primer pump)gFuel hose (primer pump to carburetor)hFuel hose (fuel joint to fuel cock)aFuel tankbFuel cockcFuel strainerdJointeFuel pumpfCarburetorgPrimer pumphFuel jointa bcdefghefgahbcd6-2Hose routing012345678910ABlowby hose, oil return hose, and cooling water hoseaBlowby hose (cylinder block to intake silencer)bOil return hose (intake silencer to crank-case)cCooling water hose (thermostat cover to crankcase)aIntake silencerabca6-3FUELFuel systemFuel tankNo. Part name Qty Remarks1 Choke holder bolt 1 M5 10 mm2 Holder 13 Grommet 14 Fuel cap 15 Rubber seal 16 Fuel strainer 17 Fuel tank 18 Bolt 1 M6 25 mm9 Grommet 210 Collar 211 Clamp 1112 Hose 113 Fuel cock 114 Fuel cock screw 1 M6 12 mm15 Hose 116 Holder 117 Fuel joint 11131112930 28272726112722211883171611151120112311111125241312119109710111464512194 Nm (0.4 kgfm, 3.0 ftlb)7 Nm (0.7 kgfm, 5.2 ftlb)4 Nm (0.4 kgfm, 3.0 ftlb)6-4Fuel tank012345678910ANo. Part name Qty Remarks18 Rubber seal 119 Choke cable nut 120 Holder 121 Choke cable 122 Fuel strainer 123 Hose 124 Hose 125 Holder 126 Hose 127 Plastic tie 3 28 Joint 129 Primer pump 130 Hose 131 Hose 11131112930 28272726112722211883171611151120112311111125241312119109710111464512194 Nm (0.4 kgfm, 3.0 ftlb)7 Nm (0.7 kgfm, 5.2 ftlb)4 Nm (0.4 kgfm, 3.0 ftlb)6-5FUELFuel systemRemoving the fuel tankCoverthefuelcomponentsusingaragtoprevent fuel from spilling out.1. Drain the fuel from the fuel tank.2. Removethemanualstarter.SeeRemoving the manual starter (7-7).3. Disconnectthefuelhosea,andthenremove the fuel tank b.4. Disconnect the fuel hoses c and d.5. Remove the fuel cock screw e.6. Remove the fuel cock f.7. Remove the fuel hoses a, c, and d.8. Remove the cap g, and then remove thefuel joint h.Removing the primer pumpCoverthefuelcomponentsusingaragtoprevent fuel from spilling out.1. Remove the holder a, and then removethe choke cable b.abcdefcdahgab6-6Fuel tank012345678910A2. Disconnect the fuel hoses c and d.3. Remove the primer pump e.4. Removetheholderf,fuelstrainerg,fuel hose c, and primer pump e.5. Remove the fuel hoses d, h, and i.Checking the fuel tank1. Checkthefueltank.Replaceifcrackedor damaged.Checking the fuel joint1. Check the fuel joint. Replace if cracked ordamaged.2. Connect the special service tool a to thefuel joint outlet a.3. Applythespecifiedpositivepressure.Replacethefueljointifthespecifiedpressurecannotbemaintainedforatleast 10 seconds.Checking the fuel strainer (tank side)1. Checkthefuelstrainer.Cleanitusingstraight gasoline if there is foreign mate-rial.Checking the fuel strainer1. Checkthefuelstrainer.Replaceifcracked or damaged.2. Connect the special service tool a to thefuel inlet a.3. Blockthefueloutletbusingarubberplugb,andthenapplythespecifiedpositivepressure.Replacethefuelstrainerifthespecifiedpressurecannotbe maintained for at least 15 seconds.ce dcgefhidVacuum/pressure pump gauge set a: 90890-06756Specified positive pressure: 50.0 kPa (0.50 kgf/cm2, 7.3 psi)50 0aa6-7FUELFuel systemChecking the primer pump1. Connect the special service tool a to theprimer pump inlet a.2. Blockthefueloutletbusingarubberplug b.3. Applythespecifiedpositivepressure.Replace the primer pump if the specifiedpressurecannotbemaintainedforatleast 30 seconds.Installing the primer pump1. Connect the fuel hoses a, b, and c tothejointd,andthenfastenthemusingthe plastic ties e.2. Installtheclampsfandgtemporarilyontothefuelhosesa,b,c,andh,and then connect the fuel hose to the fuelstrainer i and primer pump j.3. Fasten the fuel hose b, c and h usingthe clamps f.4. Install the holder k.5. Install the primer pump j to the holdersl.6. Connectthefuelhosea,andthenfasten it using the clamp g.7. Connectthefuelhoseh,andthenfasten it using the clamp g.Leakage tester a: 90890-06840Specified positive pressure:200.0 kPa (2.00 kgf/cm2, 29.0 psi)Leakage tester a: 90890-06840Specified positive pressure:166.7 kPa (1.667 kgf/cm2, 24.2 psi)bababbaabceadabhigffjkcfgljga6-8Fuel tank012345678910A8. Pass the choke cable m through the holeinthebottomcowling,andthentightenthechokecablenutntothespecifiedtorque.9. Insertthecableendaintotheholeofchoke lever.10. Placetheoutertubeendbofchokecablemsothatitcontactsthestopperc, and then install the holder n.11. Tightenthechokeholderboltotothespecified torque.Installing the fuel tank1. Install the fuel joint a.2. Installtheclampsbandctemporarilyontothefuelhosesd,e,andf,andthenconnectthehosestothefuelcockg.3. Fastenthefuelhosesusingtheclampsb, and then install the holder h.4. Install the fuel cock g.5. Tightenthefuelcockscrewitothespecified torque.Choke cable nut n:4 Nm (0.4 kgfm, 3.0 ftlb)Choke holder bolt o: 4 Nm (0.4 kgfm, 3.0 ftlb)hgmnnaocmobadfe ghcbccg6-9FUELFuel system6. Connectthehosesdandf,andthenfasten them using the clamps c.7. Connectthehosee,andthenfastenitusing the clamp c.8. Insert the protrusion a of the fuel tank jinto the grommet k.9. Install the manual starter. See Installingthe manual starter (7-10).Fuel cock screw i:7 Nm (0.7 kgfm, 5.2 ftlb)idfcecjka6-10Intake silencer012345678910AIntake silencerNo. Part name Qty Remarks1 Hose 12 Hose 13 Bolt 1 M6 35 mm4 Washer 15 Collar 16 Throttle cam 17 Lever 18 Holder 19 Clamp 310 Gasket 1 11 Throttle link rod 112 Intake manifold bolt 2 M6 25 mm13 Intake manifold 114 Gasket 2 15 Spacer 116 Cap 117 Hose 121202017161110293456781415141312189921221923112 Nm (1.2 kgfm, 8.9 ftlb)Fuel tank / Intake silencer6-11FUELFuel systemNo. Part name Qty Remarks18 Carburetor assembly 119 Cap 120 Bolt 2 M6 85 mm21 Washer 222 Intake silencer 123 O-ring 1 21202017161110293456781415141312189921221923112 Nm (1.2 kgfm, 8.9 ftlb)6-12Intake silencer012345678910ARemoving the throttle cable and throttle link1. Loosenthescrewa,andthenremovethe cap b and throttle link rod c.2. Remove the throttle cables d.3. Remove the washer e, collar f, throttlecam g, lever h and holder i.Removing the carburetorCoverthefuelcomponentsusingaragtoprevent fuel from spilling out.1. Remove the blowby hose a.2. Removetheintakemanifoldbandgasket c.3. Disconnect the fuel hose d and oil returnhose e.4. Remove the intake silencer f, O-ring g,carburetor h, gaskets i, and spacer j.5. Remove the fuel hose k.cbadefghiabcedkiijhfg6-13FUELFuel systemInstalling the carburetorDonotreuseanO-ringorgasket,alwaysreplace it with a new one.1. Installtheclampsaandbtemporarilyonto the fuel hose c.2. Connectthefuelhosec,andthenfasten it using the clamp a.3. Install new gaskets d, the spacer e, thecarburetorf,anewO-ringg,andtheintakesilencerhtotheintakemanifoldi.4. Connecttheoilreturnhosejandfuelhosec,andthenfastenthefuelhoseusing the clamp b.5. Installanewgasketkandtheintakemanifoldi,andthentightentheintakemanifold bolt l to the specified torque.6. Install the blowby hose m.Installing the throttle cable and throttle link1. Install the lever a, throttle cam b, collarc, washer d, and holder e.2. Turnthethrottlegriptothefullyclosedposition.cabddefhigjcbIntake manifold bolt l: 12 Nm (1.2 kgfm, 8.9 ftlb)ikllmdcbae6-14Intake silencer012345678910A3. Install the shorter cable f to the sectiona of the bracket g.4. Installthethrottlecableh,andthentightenthelocknutsbtothespecifiedtorque.5. Install the throttle link rod i and cap j,and then tighten the throttle link screw kto the specified torque.Adjusting the throttle cable and throttle link1. Loosen the locknuts a.2. Turnthethrottlegriptothefullyopenposition.3. Adjustthelengthofcableasothatthestopper b of the throttle cam b contactssection c of the bracket c.4. Adjust the length of cable d so that thereis no clearance between the cable end dand the section e of the throttle cam b.5. Checkthatthesectionbonthethrottlecamcontactsstoppercwhenthethrottlegripisinthefullyopenposition,andthatthesectionbcontactsstopperfwhenthethrottlegripisinthefullyclosed position.6. Tightenthethrottlecablelocknutsatothe specified torque.Throttle cable locknut b: 4 Nm (0.4 kgfm, 3.0 ftlb)Throttle link screw k: 1.5 Nm (0.15 kgfm, 1.11 ftlb)hgba fkjiaabccabedbdbcf6-15FUELFuel system7. Loosen the throttle link screw e.8. Turnthethrottlegriptothefullyopenposition.9. Whilepullingtheleverg,tightenthethrottlelinkscrewetothespecifiedtorque.10. Checkthatthethrottlelinkisinthefullyopenandfullyclosedpositionswhenturningthethrottlegriptothefullyopenand fully closed positions.Throttle cable locknut a: 4 Nm (0.4 kgfm, 3.0 ftlb)Throttle link screw e: 1.5 Nm (0.15 kgfm, 1.11 ftlb)aae g6-16Carburetor012345678910ACarburetorNo. Part name Qty Remarks1 Throttle stop screw 1 M3 15 mm2 Spring 13 Throttle link screw 1 M4 6 mm4 Spring 15 O-ring 1 6 Pilot screw 17 Pilot jet 18 Gasket 1 9 Float chamber 110 Screw 2 M4 12 mm11 O-ring 1 12 Drain screw 113 Pin 114 Spring 115 Main nozzle 116 Main jet 117 Float 112101112564191514131618177310891.5 Nm (0.15 kgfm, 1.11 ftlb)A B 20A For European marketB For Oceanian marketIntake silencer / Carburetor6-17FUELFuel systemNo. Part name Qty Remarks18 Clip 119 Needle valve 120 Pilot screw 112101112564191514131618177310891.5 Nm (0.15 kgfm, 1.11 ftlb)A B 20A For European marketB For Oceanian market6-18Carburetor012345678910ADisassembling the carburetor1. Remove the drain screw a.2. Remove the float chamber b and gasketc.3. Removethespring d,andthenremovethe pin e.4. Removethefloatf,needlevalveg,and clip h.5. Remove the main jet i and main nozzlej. 6. Removethepilotjetkandpilotscrewl.A For European marketB For Oceanian marketChecking the carburetor1. Checkthatthethrottlevalveoperatessmoothly.2. Checktheairandfuelpassages.Cleanthecarburetorbodyifthereisdirtorforeign material.3. Blowcompressedairintoallpassagesandjets.WARNING! Whenusingcompressedair,wearsafetyglassesorsafetygoggles.Otherwise,eyeinjurycouldresultfromflyingdebrisor liquid.4. Check the main jet, pilot air jet, and mainnozzle.Cleanifthereisdirtorresidue.NOTICE: Donotusesteelwiretocleanthejets.Otherwise,thejetdiameterscouldbeenlarged,whichcould seriously affect performance.bacedghfPilot screw driver m: 90890-06673jiABkllm6-19FUELFuel system5. Checktheneedlevalve.Replaceifdeformed or worn.6. Checkthefloat.Replaceifcrackedordeformed.Assembling the carburetorDonotreuseanO-ringorgasket,alwaysreplace it with a new one.1. Install the main nozzle a and main jet b.2. Installtheneedlevalvec,clipd,andfloat e.3. Installthefloatpinftothespecifiedinstallation position a.4. Install the spring g.5. Measurethefloatheightb.Adjustthefloat height by bending the tab c if out ofspecification.TIP:When measuring the float height b hold thecarburetor body at angle of 45 so that thereis no load on the needle valve spring.6. Install a new gasket h, the float chamberi, a new O-ring j, and the drain screwk.abcdefgPosition a: 1.0 mm (0.04 in)Float height b (reference data): 10.0 mm (0.4 in)afgcbe456-20Carburetor012345678910A7. Installthepilotjetl,thespringm,anew O-ring n, and the pilot screw o.A For European marketB For Oceanian market8. Turn the pilot screw o in until it is lightlyseated, and then turn it out the specifiednumber of turns.Pilot screw driver p: 90890-06673Pilot screw setting:F4B: 1 3/8 3/4 turns out F5A: 2 1/2 3/4 turns out F6C: 1 3/8 3/4 turns outikhjlmnoABop6-21FUELFuel systemFuel pumpNo. Part name Qty Remarks1 Fuel pump 12 Fuel pump screw 4 M4 25 mm3 Cover 14 Diaphragm 1 5 Fuel pump valve screw 2 M3 5 mm6 Valve 27 Fuel pump body 2 18 Plunger 19 Nut 410 Spring 111 Fuel pump body 1 112 Spring 113 Pin 114 Diaphragm 1 15 Fuel pump bolt 2 M6 30 mm16 O-ring 1 1412137651654222915151081692993112 Nm (0.2 kgfm, 1.5 ftlb)0.5 Nm (0.05 kgfm, 0.37 ftlb)7 Nm (0.7 kgfm, 5.2 ftlb)6-22Fuel pump012345678910ARemoving the fuel pump1. Remove the fuel pump a and O-ring b.Checking the fuel pump1. Connect the special service tool a to thefuel pump inlet a.2. Blockthefuelpumpoutletbusingtherubberplugb,andthenapplythespecifiedpositivepressure.Checkthatthere is no air leakage.3. Connect the special service tool a to thefuel pump outlet b.4. Blockthefuelpumpinletausingtherubberplugb,andthenapplythespecifiedpositivepressure.Checkthatthere is no air leakage.Disassembling the fuel pump1. Remove the cover a, diaphragm b, andfuel pump body 2 c.2. Align the slot a in the fuel pump body 1dwiththeholebintheplungerebyturning the plunger e.3. Removethepinfbypushingtheplunger and diaphragm.Vacuum/pressure pump gauge set a: 90890-06756Specified positive pressure: 50.0 kPa (0.50 kgf/cm2, 7.3 psi)ba50 0abbaSpecified positive pressure: 50.0 kPa (0.50 kgf/cm2, 7.3 psi)50 0ababc baab ed6-23FUELFuel system4. Removethediaphragmg,springh,plunger e, and spring i.5. Remove the valves j.Checking the diaphragm and valve1. Check the diaphragm. Replace if torn.2. Check the valve. Replace if deformed orworn.Assembling the fuel pumpBeforeassemblingthefuelpump,cleanthepartsandsoakthevalvesanddiaphragmingasoline to obtain proper operation of the fuelpump.1. Install the valves a, and then tighten thefuelpumpvalvescrewsbtothespeci-fied torque.2. Install the springs c and d, plunger e,and diaphragm f.3. Aligntheholeaintheplungerewiththeholebinthediaphragmfbypushing the plunger and diaphragm.4. Install the pin g.5. Turntheplungersothattheprotrusionsc in the diaphragm f fit into the slots din the fuel pump body 1 h.fhgiejjFuel pump valve screw b: 0.5 Nm (0.05 kgfm, 0.37 ftlb)aabbcfdegba ef6-24Fuel pump012345678910A6. Installthefuelpumpbody2i,anewdiaphragm j, and the cover k, and thentightenthefuelpumpscrewsltothespecified torque.Installing the fuel pump1. Install a new O-ring a and the fuel pumpb,andthentightenthefuelpumpboltsc to the specified torque.Fuel pump screw l: 2 Nm (0.2 kgfm, 1.5 ftlb)Fuel pump bolt c: 7 Nm (0.7 kgfm, 5.2 ftlb)ccddfhijllkabccPOWRPower unit 7Power unit (check and adjustment) ................................. 7-1Checking the compression pressure......................................... 7-1Checking the ignition timing...................................................... 7-1Checking the CDI unit air gap................................................... 7-1Adjusting the CDI unit air gap .................................................... 7-2Checking the valve clearance................................................... 7-2Adjusting the valve clearance .................................................... 7-3Manual starter .................................................................... 7-5Removing the manual starter.................................................... 7-7Disassembling the manual starter............................................. 7-7Checking the manual starter..................................................... 7-7Checking the spiral spring......................................................... 7-8Assembling the manual starter.................................................. 7-8Installing the manual starter.................................................... 7-10Adjusting the start-in-gear protection cable............................. 7-10Measuring the starter rope...................................................... 7-10Power unit assembly...................................................... 7-11Removing the power unit ......................................................... 7-12Installing the power unit ........................................................... 7-14Flywheel magnet............................................................. 7-18Removing the flywheel magnet............................................... 7-19Installing the flywheel magnet................................................. 7-19Crankcase........................................................................ 7-21Removing the oil pump ............................................................ 7-23Removing the oil seal housing................................................ 7-23Removing the crankcase......................................................... 7-23Checking the crankcase.......................................................... 7-24Checking the rotor assembly................................................... 7-24Checking the oil strainer.......................................................... 7-25Checking the oil seal housing .................................................. 7-25Installing the crankcase........................................................... 7-25Installing the oil pump .............................................................. 7-26Installing the oil seal housing.................................................. 7-26Cylinder head.................................................................. 7-27Removing the cylinder head.................................................... 7-29Disassembling the cylinder head ............................................. 7-29Checking the cylinder head..................................................... 7-30Checking the rocker arm......................................................... 7-30Checking the push rod............................................................ 7-30Checking the valve spring....................................................... 7-30Checking the valve.................................................................. 7-31Checking the valve guide........................................................ 7-31012345678910AReplacing the valve guide....................................................... 7-32Checking the valve seat.......................................................... 7-32Refacing the valve seat........................................................... 7-33Checking the spark plug.......................................................... 7-35Checking the thermostat cover anode ..................................... 7-35Checking the thermostat......................................................... 7-35Assembling the cylinder head................................................. 7-36Installing the cylinder head...................................................... 7-37Cylinder block................................................................. 7-39Disassembling the cylinder block............................................ 7-40Checking the piston diameter.................................................. 7-40Checking the cylinder bore...................................................... 7-41Checking the piston ring.......................................................... 7-41Checking the piston ring end gap............................................ 7-41Checking the piston ring groove.............................................. 7-42Checking the piston ring side clearance .................................. 7-42Checking the piston pin boss inside diameter......................... 7-42Checking the piston pin diameter............................................ 7-42Checking the connecting rod small end inside diameter and big end inside diameter........................................................... 7-42Checking the crankshaft.......................................................... 7-43Checking the connecting rod oil clearance .............................. 7-43Checking the cylinder block ..................................................... 7-44Checking the camshaft............................................................ 7-44Checking the valve lifter.......................................................... 7-45Assembling the cylinder block................................................. 7-457-1POWRPower unitPower unit (check and adjustment)Checking the compression pressure1. Starttheengine,warmitupfor5min-utes, and then stop it.2. Remove the clip from the engine shut-offswitch.3. Disconnect the spark plug cap, and thenremove the spark plug. NOTICE: Beforeremovingthesparkplug,removeanydirt or dust in the spark plug well thatmay fall into the cylinder.4. Install the special service tool a.5. Fully open the throttle.6. Pullthestarterhandlequicklyseveraltimestocrankuntilthereadingonthecompressiongaugestabilizes,andthenmeasure the compression pressure.TIP:Whenpullingthestarterhandletocranktheengine,thecompressionpressuremayvarydepending on the speed at which the starterhandle is pulled.7. Remove the special service tool.8. Installthesparkplug.Seestep4inInstalling the cylinder head (7-37).9. Connect the spark plug cap.Checking the ignition timing1. Install the special service tools a and bto the spark plug wire a.2. Start the engine and warm it up until theidle speed stabilizes at 14501550 r/min.3. Check that the pointer b on the manualstarterisalignedwiththespecifiedignitiontimingmarkontheflywheelmagnet.TIP:Setthedigitaltachometertothe2-cycle1-cylindermodebecausethisengineignitesthe spark plug once per crankshaft rotation.Checking the CDI unit air gapDonotturntheflywheelmagnetcounter-clockwise.Otherwise,thewaterpumpimpeller could be damaged.Compression gauge a: 90890-03160Minimum compression pressure (reference data):700.0 kPa (7.00 kgf/cm2, 101.5 psi) at 20 C (68 F)aDigital tachometer a: 90890-06760Timing light b: 90890-03141Ignition timing: BTDC 79 at 1500 r/minbaab7-2Power unit (check and adjustment)012345678910A1. Removethemanualstarter.SeeRemoving the manual starter (7-7).2. Turntheflywheelmagnetclockwisetoalignthepermanentmagnetawiththeprotrusions b on the CDI unit.3. Measure the CDI unit air gap c.Adjusting the CDI unit air gapDonotturntheflywheelmagnetcounter-clockwise.Otherwise,thewaterpumpimpeller could be damaged.1. Turntheflywheelmagnetclockwisetoalignthepermanentmagnetawiththeprotrusions b on the CDI unit.2. LoosentheCDIunitboltsa,andthenadjust the CDI unit air gap c.3. TightentheCDIunitboltsatothespecified torque.4. Measure the CDI unit air gap.Checking the valve clearanceMeasurethevalveclearanceswhentheengine is cold.Donotturntheflywheelmagnetcounter-clockwise.Otherwise,thewaterpumpimpeller could be damaged.1. Remove the clip from the engine shut-offswitch.2. Removetheengineshut-offswitchleada,groundleadsaandbfromtheholders c and d.3. Loosentheboltseintheordera,b,and so on, and then remove the cylinderhead cover f and gasket g.CDI unit air gap c: 0.40.6 mm (0.0160.024 in)CDI unit air gap c: 0.40.6 mm (0.0160.024 in)cbacbaaCDI unit bolt a:10 Nm (1.0 kgfm, 7.4 ftlb)aabdca7-3POWRPower unit4. Slowly pull the starter handle to align theTDC mark b on the flywheel magnet andthe pointer c of the manual starter.TIP:Make sure that the rocker arms are not push-ing the intake and exhaust valves.5. Measuretheintakeandexhaustvalveclearances d and e.6. Install a new gasket h, the cylinder headcoverf,theholdersc,d,i,andground lead b, and then tighten the boltseintheordera,b,andsoon.NOTICE: Donotreuseagasket,always replace it with a new one.7. Installthegroundleadsa,bandengineshut-offswitchleadatotheholders c and d.Adjusting the valve clearanceAdjust the valve clearances when the engineis cold.ecadbeeefgbcedValve clearance:Intake d and exhaust e:0.080.12 mm (0.0030.005 in)eeibcdfhacebdeabdca7-4Power unit (check and adjustment)012345678910ADonotturntheflywheelmagnetcounter-clockwise.Otherwise,thewaterpumpimpeller could be damaged.1. AligntheTDCmarkaontheflywheelmagnet and the pointer b of the manualstarter.2. Loosenthevalveadjustinglocknuta,and then turn the rocker arm pivot b untilthe specified valve clearance is obtained.TIP: Todecreasethevalveclearance,turntherocker arm pivot in direction c. Toincreasethevalveclearance,turntherocker arm pivot in direction d.3. Tightenthevalveadjustinglocknutatothe specified torque, and then check thevalve clearances.Valve clearance:Intake and exhaust: 0.080.12 mm (0.0030.005 in)abaabbcdaabbValve adjusting locknut a:10 Nm (1.0 kgfm, 7.4 ftlb)abb7-5POWRPower unitManual starterNo. Part name Qty Remarks1 Cap 12 Starter handle 13 Rubber seal 14 Starter rope 1 1800.0 mm (70.9 in) (reference data)5 Bolt 2 M6 35 mm6 Guide 17 Bolt 1 M6 20 mm8 Starter plunger 19 Spring 110 Cover 111 Sheave drum 112 Spring 213 Drive pawl 214 Clip 115 Drive plate 116 Drive plate screw 117 E-clip 110557891718191112 121313141516123467 Nm (0.7 kgfm, 5.2 ftlb)7-6Manual starter012345678910ANo. Part name Qty Remarks18 Plate 119 Spiral spring 110557891718191112 121313141516123467 Nm (0.7 kgfm, 5.2 ftlb)7-7POWRPower unitRemoving the manual starter1. Disconnectthestart-in-gearprotectioncable a.2. Remove the manual starter b.Disassembling the manual starter1. Aligntheprotrusionaonthestarterplunger a and the mark b on the man-ual starter b.2. While holding the starter rope c, turn thesheave dram d 34 turns clockwise.3. Removethedriveplatee,drivepawlsf,anddrivepawlspringsg,andthenremove the clip h from the drive plate e.4. Removethesheavedrumdandplatei.5. Remove the spiral spring j. WARNING!Thespiralspringcanpopout.Coverthespiralspringwithragswhenremoving it.6. Removethestarterropec,E-clipk,starter plunger a, starter plunger springl, and guide m.Checking the manual starter1. Check the guide, drive pawls, drive plate,plate,andstarterplunger.Replaceifcracked or damaged.2. Check the clip, drive pawl springs, E-clip,andstarterplungerspring.Replaceifbent, cracked, or damaged.babcd baaggffheidjcmalk7-8Manual starter012345678910A3. Checkthesheavedrum.Replaceifcracked or damaged.4. Checkthestarterhandle.Replaceifcracked or damaged.5. Checkthestarterrope.Replaceifdamaged.Checking the spiral spring1. Checkthespiralspringa.Replaceifbent, cracked, or damaged.Assembling the manual starter1. Install the guide a.2. Installthestarterplungerbandstarterplunger spring c, and then install the E-clip d.3. Route the starter rope e.4. Tie a knot in both ends a and b of thestarter rope e.TIP:Makesuretoleavec12.0 mm(0.47 in)ormore at the end a of the starter rope.5. Wind the starter rope e twice around thesheavedrumfcounterclockwise,andthen fit the starter rope e into the slot d.6. Hooktheendeofthespiralspringgontothesectionfofthesheavedrumf,andtheninstallthespiralspringginto the sheave drum f. WARNING! Thespiralspringcanpopout.Coverthespiral spring with rags when installingit.7. Install the plate h.Starter rope length (reference data): 1800.0 mm (70.9 in)aabbccdebacef defgfg7-9POWRPower unit8. Installthesheavedrumfwiththeprotrusiongonthestarterplungerband the mark h of the manual starter ialigned.9. Turn the sheave drum f to hook the endk of the spiral spring g onto the sectionm in the manual starter i.10. Install the drive pawl springs j and drivepawls k.11. Install the clip l to the drive plate m.12. Installthedriveplatembyaligningtheprotrusionnonthedrivepawlskandthe slots p in the drive plate m, and thentightenthedriveplatescrewntothespecified torque.13. Aligntheprotrusiongonthestarterplungerbandthemarkhonthemanual starter i.14. While holding the starter rope e, turn thesheavedramf3turnscounterclock-wise.15. Remove the starter rope e from the slotd, and then let the sheave drum f turnslowlysothatthestarterropeeiswound around the sheave drum f.kfhimhbg gjkDrive plate screw n:7 Nm (0.7 kgfm, 5.2 ftlb)lmlmnkkkp pnnnn ppmkkieh fbgd7-10Manual starter012345678910A16. Aligntheprotrusiongonthestarterplungerbandthemarkhonthemanual starter i.17. Pull the starter handle o several times tocheckthatthesheavedrumturnssmoothly and to check the starter rope efor slack.Installing the manual starter1. Install the manual starter a.2. Connectthestart-in-gearprotectioncable b.Adjusting the start-in-gear protection cableMakesuretoremovetheclipfromtheengineshut-offswitchbeforecheckingthe start-in-gear protection.1. Move the shift lever to the N position.2. Loosen the start-in-gear protection cablelocknuta,andthenaligntheprotrusionb on the starter plunger a and the markc on the manual starter b.3. Tighten the start-in-gear protection cablelocknut a to the specified torque.4. Move the shift lever to the F or R position.5. Checkthatthestarterhandlecannotbepulled.Measuring the starter rope1. Pullthestarterhandleatoextendthestarterropebcompletely,andthenmeasurethestarterropeextendedlength a.oeghbbiabStart-in-gear protection cable locknut a:2 Nm (0.2 kgfm, 1.5 ftlb)Starter rope extended length a:1430.01570.0 mm (56.361.8 in)baacbaab7-11POWRPower unitPower unit assemblyNo. Part name Qty Remarks1 Dowel 22 Gasket 1 3 Engine shut-off switch nut 14 Engine shut-off switch 15 Plastic tie 4 6 Bolt 4 M6 12 mm7 Holder 18 Bracket 19 CDI unit coupler 110 Ground lead 111 Power unit assembly 112 Plate 113 Bolt 5 M6 15 mm14 Power unit mounting bolt 4 M6 50 mm15 Power unit mounting bolt 5 M6 40 mm16 Cover 1121466587141516131313141515131255116369102 Nm (0.2 kgf m, 1.5 ftlb)12 Nm (1.2 kgfm, 8.9 ftlb)12 Nm (1.2 kgfm, 8.9 ftlb)7-12Power unit assembly012345678910ARemoving the power unitCoverthe