Yamaha YZ125 2009 Owner's Service Manual
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Yamaha YZ125 2009 Owner's Service Manual

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2009
q Read this manual carefully before operating this vehicle.
OWNER'S SERVICE MANUAL
YZ125Y
LIT-11626-22-54
1C3-28199-14

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  • Page 1 2009 q Read this manual carefully before operating this vehicle. OWNER’S SERVICE MANUAL YZ125Y LIT-11626-22-54 1C3-28199-14...
  • Page 2 Read this manual carefully before operating this vehicle. This manual should stay with this vehicle if it is sold.
  • Page 3 YZ125Y OWNER'S SERVICE MANUAL ©2008 by Yamaha Motor Corporation, U.S.A. 1st Edition, April 2008 All rights reserved. Any reprinting or unauthorized use without the written permission of Yamaha Motor Corporation U.S.A. is expressly prohibited. Printed in Japan P/N. LIT-11626-22-54...

  • Page 4: Important Manual Information

    INTRODUCTION IMPORTANT MANUAL INFORMATION Congratulations on your purchase of a Yamaha YZ series. This model is the culmination of Particularly important information is distin- Yamaha's vast experience in the production of guished in this manual by the following nota- pacesetting racing machines. It represents the tions.

  • Page 5: Safety Information

    SAFETY INFORMATION • PARK THE MACHINE CAREFULLY; TURN OFF THE ENGINE. THIS MACHINE IS DESIGNED STRICTLY Always turn off the engine if you are going to FOR COMPETITION USE, ONLY ON A leave the machine. Do not park the machine CLOSED COURSE.
  • Page 6 YAMAHA MOTOR CORPORATION, U.S.A. YZ MOTORCYCLE LIMITED WARRANTY...
  • Page 7 F.I.M. MACHINE WEIGHTS Weights of machines without fuel The minimum weights for motocross machines are: for the class 125 cc: minimum 88 kg (194 lb) for the class 250 cc: minimum 98 kg (216 lb) for the class 500 cc: minimum 102 kg (225 lb) In modifying your machine (e.g., for weight re- duction), take note of the above limits of weight.

  • Page 8: General Information

    HOW TO USE THIS MANUAL FINDING THE REQUIRED PAGE 1. This manual consists of seven chapters; "General Information", "Specifications", "Regular inspec- tion and adjustments", "Engine", "Chassis", "Electrical" and "Tuning" 2. The table of contents is at the beginning of the manual. Look over the general layout of the book before finding then required chapter and item.
  • Page 9 HOW TO READ DESCRIPTIONS To help identify parts and clarify procedure steps, there are exploded diagrams at the start of each removal and disassembly section. 1. An easy-to-see exploded diagram "1" is provided for removal and disassembly jobs. 2. Numbers "2" are given in the order of the jobs in the exploded diagram. A number that is enclosed by a circle indicates a disassembly step.
  • Page 10 ILLUSTRATED SYMBOLS (Refer Illustrated symbols "1" to "7" are used to identi- fy the specifications appearing in the text. to the illustration) 1. With engine mounted 2. Filling fluid 3. Lubricant 4. Special tool 5. Tightening 6. Specified value, Service limit 7.

  • Page 11: Table Of Contents

    TABLE OF CONTENTS GENERAL INFORMATION SPECIFICATIONS REGULAR INSPECTION AND ADJUSTMENTS ENGINE CHASSIS ELECTRICAL TUNING...

  • Page 12: Table Of Contents

    CONTENTS CHAPTER 1 GENERAL INFORMATION LOCATION OF IMPORTANT LABELS ..1-1 DESCRIPTION ........... 1-2 MACHINE IDENTIFICATION ..... 1-3 INCLUDED PARTS ........1-4 IMPORTANT INFORMATION ....1-5 CHECKING OF CONNECTION ....1-7 SPECIAL TOOLS........1-8 CONTROL FUNCTIONS ......1-11 STARTING AND BREAK-IN ....1-13 TORQUE-CHECK POINTS ......

  • Page 13: Table Of Contents

    CHAPTER 4 ENGINE SEAT, FUEL TANK AND SIDE COVERS . 4-2 EXHAUST PIPE AND SILENCER ..... 4-4 RADIATOR..........4-6 CARBURETOR AND REED VALVE ..4-9 CYLINDER HEAD, CYLINDER AND PISTON ............ 4-17 CLUTCH ........... 4-28 KICK SHAFT AND SHIFT SHAFT... 4-34 YPVS GOVERNOR ........
  • Page 14 CHAPTER 6 ELECTRICAL ELECTRICAL COMPONENTS AND WIRING DIAGRAM ........6-2 IGNITION SYSTEM ........6-4 CHAPTER 7 TUNING ENGINE ............7-1 CHASSIS..........7-10...

  • Page 15: Location Of Important Labels

    LOCATION OF IMPORTANT LABELS GENERAL INFORMATION LOCATION OF IMPORTANT LABELS Please read the following important labels carefully before operating this vehicle.

  • Page 16: Description

    DESCRIPTION DESCRIPTION 1. Clutch lever 14. Fuel cock 2. Engine stop switch 15. Air filter 3. Front brake lever 16. Drive chain 4. Throttle grip 17. Shift pedal 5. Radiator cap 18. Starter knob 6. Fuel tank cap 19. Front fork 7.

  • Page 17: Machine Identification

    There are two significant reasons for knowing the serial number of your machine: 1. When ordering parts, you can give the num- ber to your Yamaha dealer for positive iden- tification of the model you own. 2. If your machine is stolen, the authorities will need the number to search for and identify your machine.

  • Page 18: Included Parts

    INCLUDED PARTS INCLUDED PARTS NIPPLE WRENCH This nipple wrench "1" is used to tighten the DETACHABLE SIDESTAND spoke. This sidestand "1" is used to support only the machine when standing or transporting it. • Never apply additional force to the side- stand.

  • Page 19: Important Information

    5. Keep away from fire. ALL REPLACEMENT PARTS 1. We recommend to use Yamaha genuine parts for all replacements. Use oil and/or grease recommended by Yamaha for as- sembly and adjustment.
  • Page 20 IMPORTANT INFORMATION BEARINGS AND OIL SEALS 1. Install the bearing(s) "1" and oil seal(s) "2" with their manufacturer's marks or numbers facing outward. (In other words, the stamped letters must be on the side ex- posed to view.) When installing oil seal(s), apply a light coating of lightweight lithium base grease to the seal lip(s).

  • Page 21: Checking Of Connection

    CHECKING OF CONNECTION CHECKING OF CONNECTION Dealing with stains, rust, moisture, etc. on the connector. 1. Disconnect: • Connector 2. Dry each terminal with an air blower. 3. Connect and disconnect the connector two or three times. 4. Pull the lead to check that it will not come off. 5.

  • Page 22: Special Tools

    SPECIAL TOOLS SPECIAL TOOLS • For U.S.A. and Canada, use part number The proper special tools are necessary for starting with "YM-", "YU-" or "ACC-". complete and accurate tune-up and assembly. • For others, use part number starting with Using the correct special tool will help prevent "90890-".
  • Page 23 SPECIAL TOOLS Tool name/Part number How to use Illustration Piston pin puller set This tool is used to remove YU-1304, 90890-01304 the piston pin. Fuel level gauge "1" This gauge is used to mea- YM-1312-A, 90890-01312 sure the fuel level in the float Fuel level gauge adaptor "2"...
  • Page 24 Dynamic spark tester This instrument is necessary YM-34487 for checking the ignition sys- Ignition checker tem components. 90890-06754 YAMAHA Bond No. 1215 This sealant (Bond) is used ® (ThreeBond No. 1215) for crankcase mating surface, 90890-85505 etc. 1-10...

  • Page 25: Control Functions

    CONTROL FUNCTIONS CONTROL FUNCTIONS KICKSTARTER CRANK Rotate the kickstarter crank "1" away from the ENGINE STOP SWITCH engine. Push the starter down lightly with your The engine stop switch "1" is located on the left foot until the gears engage, then kick smoothly handlebar.
  • Page 26 CONTROL FUNCTIONS REAR BRAKE PEDAL The rear brake pedal "1" is located on the right side of the machine. Press down on the brake pedal to activate the rear brake. FUEL COCK The fuel cock supplies fuel from the tank to car- buretor and also filters the fuel.

  • Page 27: Starting And Break-In

    STARTING AND BREAK-IN STARTING AND BREAK-IN chine in a well-ventilated area. FUEL AIR FILTER MAINTENANCE Mix oil with the gas at the ratio specified below. According to "CLEANING THE AIR FILTER Always use fresh, name-brand gasoline, and ELEMENT" section in the CHAPTER 3, apply mix the oil and gas the day of the race.
  • Page 28 STARTING AND BREAK-IN 5. Allow the engine to cool. Restart the engine and operate the machine as in the step above for five minutes. Then, very briefly shift to the higher gears and check full-throt- tle response. Stop and check the spark plug. 6.

  • Page 29: Torque-Check Points

    TORQUE-CHECK POINTS TORQUE-CHECK POINTS Frame construction Frame to rear frame Combined seat and fuel tank Fuel tank to frame Exhaust system Silencer to rear frame Engine mounting Frame to engine Engine bracket to engine Engine bracket to frame Steering Steering stem to handlebar Steering stem to frame Steering stem to upper bracket Upper bracket to handlebar...

  • Page 30: Cleaning And Storage

    CLEANING AND STORAGE CLEANING AND STORAGE STORAGE If your machine is to be stored for 60 days or CLEANING more, some preventive measures must be tak- Frequent cleaning of your machine will en- en to avoid deterioration. After cleaning the ma- hance its appearance, maintain good overall chine thoroughly, prepare it for storage as performance, and extend the life of many com-...

  • Page 31: General Specifications

    GENERAL SPECIFICATIONS SPECIFICATIONS GENERAL SPECIFICATIONS Model name: YZ125Y (USA, CDN) YZ125 (EUROPE, ZA) YZ125Y (AUS, NZ) Model code number: 1C3H (USA, CDN) 1C3J (EUROPE) 1C3L (AUS, NZ, ZA) Dimensions: USA, AUS, NZ, ZA EUROPE, CDN Overall length 2,135 mm (84.1 in) 2,139 mm (84.2 in) Overall width 827 mm (32.6 in)
  • Page 32 GENERAL SPECIFICATIONS Clutch type: Wet, multiple-disc Transmission: Primary reduction system Gear Primary reduction ratio 64/19 (3.368) Secondary reduction system Chain drive Secondary reduction ratio 48/13 (3.692) Transmission type Constant mesh, 6-speed Operation Left foot operation Gear ratio: 31/13 (2.385) 29/15 (1.933) 27/17 (1.588) 23/17 (1.353) 24/20 (1.200)

  • Page 33: Maintenance Specifications

    MAINTENANCE SPECIFICATIONS MAINTENANCE SPECIFICATIONS ENGINE Item Standard Limit Cylinder head: Combustion chamber capacity 8.4 cm (0.296 Imp oz, 0.284 US oz) ---- Warp limit ---- 0.03 mm (0.0012 in) Cylinder: Bore size 54.000–54.014 mm (2.1260–2.1265 in) 54.1 mm (2.130 in) Taper limit ---- 0.05 mm...
  • Page 34 MAINTENANCE SPECIFICATIONS Item Standard Limit Crankshaft: Crank width "A" 55.90–55.95 mm (2.201–2.203 in) ---- Runout limit "C" 0.03 mm (0.0012 in) 0.05 mm (0.0020 in) Connecting rod big end side clearance 0.06–0.64 mm (0.002–0.025 in) ---- "D" Small end free play "F" 0.8–1.0 mm (0.031–0.039 in) 2.0 mm (0.08 in)
  • Page 35 MAINTENANCE SPECIFICATIONS Item Standard Limit Carburetor: USA, CDN EUROPE AUS, NZ, ZA Type/Manufacturer TMXχ38SS ← ← /MIKUNI I.D. mark 1C35 30 1C36 40 ---- ← Main jet (M.J.) #410 #430 ---- ← Jet needle-clip position (J.N.) 6BFY42-74- 6BFY43-74- ---- ← Cutaway (C.A.) ---- ←...
  • Page 36 MAINTENANCE SPECIFICATIONS CHASSIS Item Standard Limit Steering system: Steering bearing type Taper roller bearing ---- Front suspension: USA, CDN, ZA, EUROPE AUS, NZ Front fork travel 300 mm (11.8 in) ---- ← Fork spring free length 454 mm (17.9 in) 449 mm ←...
  • Page 37 MAINTENANCE SPECIFICATIONS Item Standard Limit Wheel: Front wheel type Spoke wheel ---- Rear wheel type Spoke wheel ---- Front rim size/material 21 × 1.60/Aluminum ---- Rear rim size/material 19 × 1.85/Aluminum ---- Rim runout limit: Radial ---- 2.0 mm (0.08 in) Lateral ---- 2.0 mm...
  • Page 38 Ignition timing (B.T.D.C.) 0.48 mm (0.019 in) ---- Advancer type Electrical ---- CDI: Magneto-model (stator)/Manufacturer 1C3-10/YAMAHA ---- Charging coil 1 resistance (color) 720–1,080 Ωat 20 °C (68 °F) ---- (Green/White-Black/Red) Charging coil 2 resistance (color) 44–66 Ωat 20 °C (68 °F) (Black-...

  • Page 39: Tightening Torques

    TIGHTENING TORQUES TIGHTENING TORQUES ENGINE △ - marked portion shall be checked for torque tightening after break-in or before each race. Tightening torque Part to be tightened Thread size Q'ty m•kg ft•lb Spark plug M14S × 1.25 Cylinder head (nut) M8 ×...
  • Page 40 TIGHTENING TORQUES Tightening torque Part to be tightened Thread size Q'ty m•kg ft•lb Oil drain bolt M10 × 1.25 Kickstarter crank M6 × 1.0 Clutch cover M6 × 1.0 Primary drive gear M8 × 1.25 Clutch boss M16 × 1.0 Clutch spring M6 ×...
  • Page 41 TIGHTENING TORQUES Tightening torque Part to be tightened Thread size Q'ty m•kg ft•lb △ Front fork protector and brake hose holder M6 × 1.0 Throttle cable cap M4 × 0.7 △ Front brake master cylinder and bracket M6 × 1.0 Brake lever mounting bolt M6 ×...
  • Page 42 TIGHTENING TORQUES Tightening torque Part to be tightened Thread size Q'ty m•kg ft•lb △ Relay arm and swingarm M14 × 1.5 △ Relay arm and connecting rod M14 × 1.5 △ Connecting rod and frame M14 × 1.5 △ Rear shock absorber and frame M10 ×...
  • Page 43 TIGHTENING TORQUES GENERAL TORQUE SPECIFICATIONS This chart specifies torque for standard fasteners with standard I.S.O. pitch threads. Torque specifi- cations for special components or assemblies are included in the applicable sections of this book. To avoid warpage, tighten multi-fastener assemblies in a crisscross fashion, in progressive stages, until full torque is reached.
  • Page 44 TIGHTENING TORQUES DEFINITION OF UNITS Unit Read Definition Measure millimeter meter Length centimeter meter Length kilogram gram Weight Newton 1 kg × m/sec Force Newton meter N × m Torque m•kg Meter kilogram m × kg Torque Pascal Pressure N/mm Newton per millimeter N/mm Spring rate...
  • Page 45 MEMO...

  • Page 46: Cable Routing Diagram

    CABLE ROUTING DIAGRAM CABLE ROUTING DIAGRAM 2-15...
  • Page 47 CABLE ROUTING DIAGRAM 1. "ENGINE STOP" button lead M. Pass the air vent hose, overflow hose and 2. Throttle cable crankcase breather hose so that they do 3. Clutch cable not contact the rear shock absorber. 4. Ground lead N. Bring the connector cover into contact with 5.
  • Page 48 CABLE ROUTING DIAGRAM 2-17...
  • Page 49 CABLE ROUTING DIAGRAM 1. High tension cord 2. "ENGINE STOP" button lead 3. Ignition coil lead 4. Clamp 5. CDI unit 6. CDI unit band 7. Radiator breather hose 8. CDI magneto lead 9. Connector cover 10. Throttle cable 11. Clutch cable 12.
  • Page 50 CABLE ROUTING DIAGRAM 2-19...
  • Page 51 CABLE ROUTING DIAGRAM 1. Master cylinder 2. Brake hose holder 3. Brake hose A. Install the brake hose so that its pipe por- tion directs as shown and lightly touches the projection on the caliper. B. Pass the brake hose into the brake hose holders.
  • Page 52 CABLE ROUTING DIAGRAM 2-21...
  • Page 53 CABLE ROUTING DIAGRAM 1. Brake hose 2. Master cylinder 3. "ENGINE STOP" button lead 4. "ENGINE STOP" button 5. Throttle cable 6. Clutch cable 7. Clamp 8. Cable guide A. Install the brake hose so that its pipe por- tion directs as shown and lightly touches the projection on the master cylinder.

  • Page 54: Maintenance Intervals

    If you are a doubt as to what intervals to follow in main- taining and lubricating your machine, consult your Yamaha dealer. After...
  • Page 55 MAINTENANCE INTERVALS After Every As re- Every Every Item break Remarks race third fifth quired ROTOR NUT Retighten ● ● MUFFLER Inspect ● ● Clean ● Retighten ● ● CRANK Inspect and clean ● ● CARBURETOR Inspect, adjust and clean ●...
  • Page 56 MAINTENANCE INTERVALS After Every As re- Every Every Item break Remarks race third fifth quired BRAKES Adjust lever position and ● ● pedal height Lubricate pivot point ● ● Check brake disc surface ● ● Check fluid level and leak- ●...
  • Page 57 Retighten sprocket bolt ● ● Inspect bearings ● Replace bearings ● Lubricate Lithium base grease ● THROTTLE, CONTROL CABLE Check routing and con- ● ● nection Lubricate Yamaha cable lube or SAE ● ● 10W-40 motor oil...

  • Page 58: Pre-Operation Inspection And Maintenance

    PRE-OPERATION INSPECTION AND MAINTENANCE PRE-OPERATION INSPECTION AND MAINTENANCE Before riding for break-in operation, practice or a race, make sure the machine is in good operating condition. Before using this machine, check the following points. GENERAL INSPECTION AND MAINTENANCE Item Routine Page Check that coolant is filled up to the radiator cap.

  • Page 59: Engine

    ENGINE ENGINE CHANGING THE COOLANT CHECKING THE COOLANT LEVEL Do not remove the radiator cap when the en- gine is hot. Do not remove the radiator cap "1", drain bolt and hoses when the engine and radia- tor are hot. Scalding hot fluid and steam Take care so that coolant does not splash may be blown out under pressure, which on painted surfaces.
  • Page 60 ENGINE • Do not mix more than one type of ethylene glycol antifreeze containing corrosion in- hibitors for aluminum engine. • Do not use water containing impurities or oil. CHECKING THE RADIATOR CAP OPENING PRESSURE 1. Attach: • Radiator cap tester "1" and adapter "2" Radiator cap tester: YU-24460-01/90890-01325 Radiator cap tester adapter:...
  • Page 61 ENGINE 3. Apply the specified pressure. 2. Adjust: • Clutch lever free play Standard pressure: 180 kPa (1.8 kg/cm , 25.6 psi) Clutch lever free play adjustment steps: a. Loosen the locknuts "1". • Do not apply pressure more than specified b.
  • Page 62 ENGINE ADJUSTING THE THROTTLE CABLE FREE PLAY LUBRICATING THE THROTTLE 1. Check: 1. Remove: • Throttle grip free play "a" • Cap cover "1" Out of specification → Adjust. • Throttle cable cap "2" Throttle grip free play "a": 3–5 mm (0.12–0.20 in) 2.
  • Page 63 ENGINE Never run the engine without the air filter el- ement in place; this would allow dirt and dust to enter the engine and cause rapid wear and possible engine damage. 1. Remove: • Seat • Fitting bolt "1" • Washer "2" •...
  • Page 64 ENGINE CHECKING THE TRANSMISSION OIL CHANGING THE TRANSMISSION OIL LEVEL 1. Start the engine and warm it up for several 1. Start the engine, warm it up for several min- minutes and wait for five minute. utes and wait for five minutes. 2.
  • Page 65 ENGINE 6. Fill: • Transmission oil Recommended oil: Yamalube 4 (10W-40) or SAE 10W- 40 type SE motor oil Oil capacity (periodic oil change): 0.66 L (0.58 Imp qt, 0.69 US qt) 7. Check: • Oil leakage 8. Check: • Transmission oil level CHECKING THE EXHAUST PIPE 9.

  • Page 66: Chassis

    CHASSIS CHASSIS d. Place the other end of the tube into a con- tainer. BLEEDING THE HYDRAULIC BRAKE e. Slowly apply the brake lever or pedal sever- SYSTEM al times. f. Pull the lever in or push down on the pedal. Hold the lever or pedal in position.
  • Page 67 CHASSIS 2. Remove: b. Turn the adjusting nut "2" until the pedal • Brake lever cover height "a" is within specified height. 3. Adjust: c. Tighten the locknut. • Brake lever position • Adjust the pedal height between the maxi- Brake lever position adjustment steps: mum "A"...
  • Page 68 CHASSIS 2. Replace: f. Loosen the bleed screw and push the brake • Brake pad caliper piston in. Brake pad replacement steps: Do not reuse the drained brake fluid. a. Remove the pad pin plug "1". g. Tighten the bleed screw. Bleed screw: 6 Nm (0.6 m•kg, 4.3 ft•lb) h.
  • Page 69 CHASSIS j. Install the pad pin plug "10". Pad pin plug: 3 Nm (0.3 m•kg, 2.2 ft•lb) b. Loosen the pad pin "3". c. Remove the rear wheel "4" and brake caliper "5". Refer to "FRONT WHEEL AND REAR WHEEL" section in the CHAPTER 5. 3.
  • Page 70 CHASSIS f. Loosen the bleed screw and push the brake caliper piston in. Do not reuse the drained brake fluid. g. Tighten the bleed screw. Bleed screw: 6 Nm (0.6 m•kg, 4.3 ft•lb) h. Install the brake pad "10" and pad pin "11". •...

  • Page 71: Specifications

    CHASSIS • While measuring the drive chain length, push • Use only designated quality brake fluid to down on the drive chain to increase its ten- avoid poor brake performance. sion. • Refill with same type and brand of brake •...

  • Page 72: Adjustments

    CHASSIS 4. Check: ADJUSTING THE DRIVE CHAIN SLACK • Drive chain stiffness "a" 1. Elevate the rear wheel by placing the suit- Clean and oil the drive chain and hold as il- able stand under the engine. lustrated. 2. Check: Stiff →...
  • Page 73 CHASSIS 2. Clean: • Dust seal "a" Turn the adjuster so that the drive chain is in • Oil seal "b" line with the sprocket, as viewed from the rear. d. Tighten the axle nut while pushing down the • Clean the dust seal and oil seal after every drive chain.
  • Page 74 CHASSIS ADJUSTING THE FRONT FORK REBOUND Stiffer "a" → Increase the compression DAMPING FORCE damping force. (Turn the adjuster "1" in.) 1. Adjust: Softer "b" → Decrease the compression • Rebound damping force damping force. (Turn the adjuster "1" By turning the adjuster "1". out.) Stiffer "a"...
  • Page 75 CHASSIS • The I.D. mark "a" is marked at the end of the spring. • Spring specification varies according to the difference in the production lot. 4. Adjust: • Spring preload Adjustment steps: a. Loosen the locknut "1". ADJUSTING THE REAR SHOCK b.
  • Page 76 CHASSIS 5. Install: • Rear frame (upper) Rear frame (upper): 32 Nm (3.2 m•kg, 23 ft•lb) • Rear frame (lower) Rear frame (lower): 29 Nm (2.9 m•kg, 21 ft•lb) ADJUSTING THE REAR SHOCK ABSORBER REBOUND DAMPING FORCE ADJUSTING THE REAR SHOCK 1.
  • Page 77 CHASSIS ADJUSTING THE REAR SHOCK CHECKING THE TIRE PRESSURE ABSORBER HIGH COMPRESSION 1. Measure: DAMPING FORCE • Tire pressure 1. Adjust: Out of specification → Adjust. • High compression damping force Standard tire pressure: By turning the adjuster "1". 100 kPa (1.0 kgf/cm , 15 psi) Stiffer "a"...
  • Page 78 CHASSIS CHECKING AND TIGHTENING THE CHECKING THE WHEELS SPOKES 1. Inspect: The following procedure applies to all of the • Wheel runout spokes. Elevate the wheel and turn it. 1. Check: Abnormal runout → Replace. • Spokes Bend/damage → Replace. Loose spoke →...
  • Page 79 CHASSIS 3. Check: • Steering smooth action Turn the handlebar lock to lock. Unsmooth action → Adjust steering ring nut. e. Loosen the steering ring nut one turn. f. Retighten the steering ring nut using the steering nut wrench. 4. Adjust: Avoid over-tightening.
  • Page 80 CHASSIS 3-27...
  • Page 81 CHASSIS LUBRICATION To ensure smooth operation of all components, A. Use Yamaha cable lube or equivalent on lubricate your machine during setup, after these areas. break-in, and after every race. B. Use SAE 10W-40 motor oil or suitable 1. All control cable chain lubricants.

  • Page 82: Electrical

    ELECTRICAL ELECTRICAL CHECKING THE SPARK PLUG 1. Remove: • Spark plug 2. Inspect: • Electrode "1" Wear/damage → Replace. • Insulator color "2" Normal condition is a medium to light tan color. CHECKING THE IGNITION TIMING Distinctly different color → Check the engine 1.
  • Page 83 ELECTRICAL 5. From TDC, rotate the rotor clockwise until the dial gauge indicates that the piston is at a specified distance from TDC. Ignition timing (B.T.D.C.): 0.48 mm (0.019 in) 6. Check: • Ignition timing Punch mark "a" on rotor should be aligned with punch mark "b"...
  • Page 84 This section is intended for those who have basic knowledge and skill concerning the servicing of Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.) Those who have little knowl- edge and skill concerning servicing are requested not to undertake inspection, adjustment, disas- sembly, or reassembly only by reference to this manual.

  • Page 85: Seat, Fuel Tank And Side Covers

    SEAT, FUEL TANK AND SIDE COVERS SEAT, FUEL TANK AND SIDE COVERS REMOVING THE SEAT, FUEL TANK AND SIDE COVERS 19 Nm (1.9 m kg, 13 ft lb) 7 Nm (0.7 m kg, 5.1 ft lb) 6 Nm (0.6 m kg, 4.3 ft lb) 7 Nm (0.7 m kg, 5.1 ft lb) 7 Nm (0.7 m kg, 5.1 ft lb) 7 Nm (0.7 m kg, 5.1 ft lb)
  • Page 86 SEAT, FUEL TANK AND SIDE COVERS REMOVING THE SIDE COVER 1. Remove: • Bolt (side cover) • Side cover (left and right) "1" Draw the side cover downward to remove it be- cause its claws "a" are inserted in the air filter case.

  • Page 87: Exhaust Pipe And Silencer

    EXHAUST PIPE AND SILENCER EXHAUST PIPE AND SILENCER REMOVING THE EXHAUST PIPE AND SILENCER 12 Nm (1.2 m kg, 8.7 ft lb) 12 Nm (1.2 m kg, 8.7 ft lb) 10 Nm (1.0 m kg, 7.2 ft lb) 12 Nm (1.2 m kg, 8.7 ft lb) 12 Nm (1.2 m kg, 8.7 ft lb) Order Part name...
  • Page 88 3. Replace: • Fiber "2" A. For USA and CDN B. Except for USA and CDN 4. Install: • Inner pipe ® Fully apply Quick gasket (Yamaha bond No.1215) or equivalent as shown. Yamaha bond No.1215 (Three ® Bond No.1215): 90890-85505...

  • Page 89: Radiator

    RADIATOR RADIATOR REMOVING THE RADIATOR 2 Nm (0.2 m kg, 1.4 ft lb) 10 Nm (1.0 m kg, 7.2 ft lb) 10 Nm (1.0 m kg, 7.2 ft lb) 10 Nm (1.0 m kg, 7.2 ft lb) 2 Nm (0.2 m kg, 1.4 ft lb) Order Part name Q'ty...
  • Page 90 RADIATOR HANDLING NOTE Do not remove the radiator cap when the en- gine and radiator are hot. Scalding hot fluid and steam may be blown out under pres- sure, which could cause serious injury. When the engine has cooled, open the radi- ator cap by the following procedure: Place a thick rag, like a towel, over the radi- ator cap, slowly rotate the cap counter-...
  • Page 91 RADIATOR 4. Tighten: • Radiator hose clamp 1, 3 "5" Radiator hose clamp 1, 3: 2 Nm (0.2 m•kg, 1.4 ft•lb) 5. Install: • Radiator guard "1" • Bolt (radiator guard) "2" Bolt (radiator guard): 10 Nm (1.0 m•kg, 7.2 ft•lb) Fit the hook "a"...

  • Page 92: Carburetor And Reed Valve

    CARBURETOR AND REED VALVE CARBURETOR AND REED VALVE REMOVING THE CARBURETOR AND REED VALVE 2 Nm (0.2 m kg, 1.4 ft lb) 2 Nm (0.2 m kg, 1.4 ft lb) 10 Nm (1.0 m kg, 7.2 ft lb) 1 Nm (0.1 m kg, 0.7 ft lb) Order Part name Q'ty...
  • Page 93 CARBURETOR AND REED VALVE DISASSEMBLING THE CARBURETOR 4 Nm (0.4 m kg, 2.9 ft lb) Order Part name Q'ty Remarks Mixing chamber top Refer to removal section. Throttle valve Needle holder Jet needle Float chamber Needle jet cover Float pin Float Valve seat Main jet...
  • Page 94 CARBURETOR AND REED VALVE HANDLING NOTE • Use a petroleum based solvent for cleaning. Blow out all passages and jets with com- Do not disassemble the venturi block "1" pressed air. and main nozzle "2" because it will cause a •...
  • Page 95 CARBURETOR AND REED VALVE CHECKING THE NEEDLE VALVE 1. Inspect: • Needle valve "1" • Valve seat "2" Grooved wear "a" → Replace. Dust "b" → Clean. Always replace the needle valve and valve seat as a set. CHECKING THE FILTER 1.
  • Page 96 CARBURETOR AND REED VALVE Keep the carburetor and fuel level gauge verti- cally when measuring the fuel level. e. If the fuel level is not within specification, in- spect the valve seat and needle valve. f. If either is worn, replace them both. g.
  • Page 97 CARBURETOR AND REED VALVE 2. Install: 2. Install: • Reed valve assembly "1" • Starter plunger "1" • Reed valve spacer "2" 3. Install: 3. Install: • Main jet holder "1" • Carburetor joint "1" • Main jet "2" • Bolt (carburetor joint) "2" •...
  • Page 98 CARBURETOR AND REED VALVE 5. Install: • Float chamber "1" • Plate "2" • Screw (float chamber) "3" 8. Install: • Mixing chamber top "1" • Screw (mixing chamber top) "2" To carburetor "3". 6. Install: • Jet needle "1" After installing, check the throttle grip for •...
  • Page 99 CARBURETOR AND REED VALVE 4. Adjust: INSTALLING THE CARBURETOR • Idle speed 1. Install: Refer to "ADJUSTING THE ENGINE • Carburetor "1" IDLING SPEED" section in the CHAPTER 3. Install the projection between the carburetor joint slots. 2. Tighten: • Bolt (air filter joint) "1" Bolt (air filter joint): 2 Nm (0.2 m•kg, 1.4 ft•lb) •...

  • Page 100: Cylinder Head, Cylinder And Piston

    CYLINDER HEAD, CYLINDER AND PISTON CYLINDER HEAD, CYLINDER AND PISTON REMOVING THE CYLINDER HEAD AND CYLINDER 20 Nm (2.0 m kg, 14 ft lb) 28 Nm (2.8 m kg, 20 ft lb) 34 Nm (3.4 m kg, 24 ft lb) 13 Nm (1.3 m kg, 9.4 ft lb) 30 Nm (3.0 m kg, 22 ft lb) 4 Nm (0.4 m kg, 2.9 ft lb)
  • Page 101 CYLINDER HEAD, CYLINDER AND PISTON REMOVING THE PISTON AND POWER VALVE 4 Nm (0.4 m kg, 2.9 ft lb) 8 Nm (0.8 m kg, 5.8 ft lb) 4 Nm (0.4 m kg, 2.9 ft lb) 5 Nm (0.5 m kg, 3.6 ft lb) Order Part name Q'ty...
  • Page 102 CYLINDER HEAD, CYLINDER AND PISTON REMOVING THE PUSH ROD 1. Remove: • Bolt (push rod) "1" • Push rod "2" Set the collar "3" included in owner's tool kit to remove the bolt (push rod). 3. Remove: • Piston ring "1" Take care not to scratch the piston or damage the piston ring by expanding it more than nec- essary.
  • Page 103 CYLINDER HEAD, CYLINDER AND PISTON 3. Measure: • Cylinder head warpage Out of specification → Resurface. Cylinder head warpage: Less than 0.03 mm (0.0012 in) Warpage measurement and resurfacing steps: a. Attach a straightedge "1" and a thickness gauge "2" on the cylinder head. 2.
  • Page 104 CYLINDER HEAD, CYLINDER AND PISTON CHECKING THE PISTON PIN AND SMALL END BEARING 1. Inspect: • Piston pin • Small end bearing Signs of heat discoloration → Replace. CHECKING THE PISTON 1. Eliminate: • Carbon deposits From the piston crown "a" and ring groove "b".
  • Page 105 CYLINDER HEAD, CYLINDER AND PISTON 3. Check: • Free play (when the piston pin "1" is in place in the piston "2") There should be no noticeable for the play. Free play exists→Replace piston pin and/or piston. 3. Measure: • Side clearance Use a thickness gauge "1".
  • Page 106 CYLINDER HEAD, CYLINDER AND PISTON Piston clearance: Standard <Limit> 0.040–0.045 mm 0.1 mm (0.004 in) (0.0016–0.0018 in) CHECKING THE COMBINATION OF PISTON AND CYLINDER 1. Check: • Cylinder mark "a" 3. Combination: Cylinder mark "a" Cylinder size Combine the piston and cylinder by the fol- 54.000–54.002 mm lowing chart.
  • Page 107 CYLINDER HEAD, CYLINDER AND PISTON Do not use a sharp instrument. Avoid scratch- ing the aluminum. 3. Install: • Thrust plate "1" • Screw (thrust plate) "2" Screw (thrust plate): INSTALLING THE POWER VALVE 4 Nm (0.4 m•kg, 2.9 ft•lb) 1.
  • Page 108 CYLINDER HEAD, CYLINDER AND PISTON INSTALLING THE PISTON RING AND 3. Install: PISTON • Piston "1" 1. Install: • Piston pin "2" • Piston ring "1" • Piston pin clip "3" • Take care not to scratch the piston or damage •...
  • Page 109 CYLINDER HEAD, CYLINDER AND PISTON INSTALLING THE CYLINDER HEAD AND CYLINDER 1. Apply: • Engine oil To piston "1", piston ring "2" and cylinder surface. 4. Install: • Collar "1" • Push rod "2" • Plain washer "3" • Bolt (push rod) "4" Bolt (push rod): 2.
  • Page 110 CYLINDER HEAD, CYLINDER AND PISTON 5. Install: 8. Install: • Gasket (power valve housing) • Engine bracket "1" • Power valve housing "1" • Bolt (engine bracket) "2" • Bolt (power valve housing) "2" Bolt (engine bracket): Bolt (power valve housing): 34 Nm (3.4 m•kg, 24 ft•lb) 4 Nm (0.4 m•kg, 2.9 ft•lb) •...

  • Page 111: Clutch

    CLUTCH CLUTCH REMOVING THE CLUTCH 10 Nm (1.0 m kg, 7.2 ft lb) 10 Nm (1.0 m kg, 7.2 ft lb) Order Part name Q'ty Remarks Refer to "CHANGING THE TRANS- Drain the transmission oil. MISSION OIL" section in the CHAP- TER 3.
  • Page 112 CLUTCH REMOVING THE CLUTCH BOSS 80 Nm (8.0 m kg, 58 ft lb) Order Part name Q'ty Remarks Push rod 1 Circlip Washer Bearing Ball Push rod 2 Nut (clutch boss) Refer to removal section. Lock washer Refer to removal section. Clutch boss Refer to removal section.
  • Page 113 CLUTCH REMOVING THE CLUTCH BOSS CHECKING THE PRIMARY DRIVEN GEAR 1. Remove: 1. Check: • Nut "1" • Circumferential play • Lock washer "2" Free play exists → Replace. • Clutch boss "3" • Gear teeth "a" Wear/damage → Replace. Straighten the lock washer tab and use the clutch holding tool "4"...
  • Page 114 CLUTCH CHECKING THE CLUTCH PLATES INSTALLING THE PUSH LEVER SHAFT 1. Measure: 1. Install: • Clutch plate warpage • Push lever shaft "1" Out of specification → Replace clutch plate as a set. Apply the lithium soap base grease on the oil Use a surface plate "1"...
  • Page 115 CLUTCH 3. Install: • Lock washer "1" • Install the clutch plates and friction plates al- • Nut (clutch boss) "2" ternately on the clutch boss, starting with a friction plate and ending with a friction plate. Nut (clutch boss): •...
  • Page 116 CLUTCH 8. Install: • Pressure plate "1" Tighten the bolts in stage, using a crisscross pattern. 9. Install: • Clutch spring "1" 12.Install: • Bolt (clutch spring) "2" • O-ring "1" Bolt (clutch spring): • Clutch cable "2" 10 Nm (1.0 m•kg, 7.2 ft•lb) Apply the lithium soap base grease on the O- ring.

  • Page 117: Kick Shaft And Shift Shaft

    KICK SHAFT AND SHIFT SHAFT KICK SHAFT AND SHIFT SHAFT REMOVING THE PRIMARY DRIVE GEAR Order Part name Q'ty Remarks Refer to "CHANGING THE TRANS- Drain the transmission oil. MISSION OIL" section in the CHAP- TER 3. Clutch cable Disconnect at engine side. Bolt (brake pedal) Shift the brake pedal downward.
  • Page 118 KICK SHAFT AND SHIFT SHAFT REMOVING THE KICK SHAFT AND SHIFT SHAFT Order Part name Q'ty Remarks Kick idle gear Kick shaft assembly Refer to removal section. Shift pedal Shift shaft Roller Shift guide Refer to removal section. Shift lever assembly Refer to removal section.
  • Page 119 KICK SHAFT AND SHIFT SHAFT REMOVING THE PRIMARY DRIVE GEAR 1. Loosen: • Bolt (primary drive gear) "1" Place an aluminum plate "a" between the teeth of the primary drive gear "2" and driven gear "3". CHECKING THE KICK SHAFT AND KICK GEAR 1.
  • Page 120 KICK SHAFT AND SHIFT SHAFT lever. • Torsion spring "3" Broken → Replace. CHECKING THE SHIFT SHAFT 1. Inspect: • Shift shaft "1" Bend/damage → Replace. CHECKING THE PRIMARY DRIVE GEAR • Spring "2" AND PRIMARY DRIVEN GEAR Broken → Replace. 1.
  • Page 121 KICK SHAFT AND SHIFT SHAFT 3. Install: • Shift lever assembly "1" • Shift guide "2" • The shift lever assembly is installed at the same time as the shift guide. • Apply the transmission oil on the bolt (seg- ment) shaft.
  • Page 122 KICK SHAFT AND SHIFT SHAFT INSTALLING THE KICK SHAFT ASSEMBLY 1. Install: • Kick gear "1" • Washer "2" • Torsion spring "3" To kick shaft "4". Make sure the stopper "a" of the torsion spring fits into the hole "b" on the kick shaft. 4.
  • Page 123 KICK SHAFT AND SHIFT SHAFT INSTALLING THE PRIMARY DRIVE GEAR 1. Install: • Spacer "1" • Primary drive gear "2" • Bolt "3" Install the primary drive gear with its depressed side toward you. 5. Install: • Crankcase cover (right) "1" Mesh the governor gear "2", and impeller shaft gear "3"...
  • Page 124 KICK SHAFT AND SHIFT SHAFT 7. Install: • Kick starter "1" • Plain washer "2" • Bolt (kick starter) "3" Bolt (kick starter) : 10 Nm (1.0 m•kg, 7.2 ft•lb) Install the kick starter closest to but not contact- ing the pillar tube "4". 8.

  • Page 125: Ypvs Governor

    YPVS GOVERNOR YPVS GOVERNOR REMOVING THE YPVS GOVERNOR Order Part name Q'ty Remarks Refer to "KICK SHAFT AND SHIFT Right crankcase cover SHAFT" section. Governor assembly Dowel pin Refer to removal section. Retainer Ball Retainer weight Plain washer Thrust bearing Collar Plate Compression spring...
  • Page 126 YPVS GOVERNOR REMOVING THE GOVERNOR INSTALLING THE GOVERNOR 1. Remove: 1. Install: • Dowel pin "1" • Governor gear "1" • Compression spring "2" While compressing the spring, remove the • Plate "3" dowel pin. • Washer "4" • Thrust bearing "5" •...
  • Page 127 YPVS GOVERNOR 3. Install: • Dowel pin "1" • While compressing the spring, install the dow- el pin. • Make sure the dowel pin fits into the groove "a" in the retainer. 4. Install: • Governor assembly "1" Align the groove "a" in the governor with the fork "b"...

  • Page 128: Water Pump

    WATER PUMP WATER PUMP DISASSEMBLING THE WATER PUMP Order Part name Q'ty Remarks Refer to "KICK SHAFT AND SHIFT Crankcase cover (right) SHAFT" section. Water pump housing cover Impeller shaft gear Dowel pin Plain washer Impeller shaft assembly Bearing Refer to removal section. Oil seal Refer to removal section.
  • Page 129 WATER PUMP REMOVING THE OIL SEAL CHECKING THE IMPELLER SHAFT GEAR 1. Inspect: • Replace the oil seal when transmission oil or • Gear teeth "a" coolant leaks out from the water pump hous- Wear/damage → Replace. ing hole at the bottom. •...
  • Page 130 WATER PUMP • Washer "5" • Circlip "6" Install the Impeller shaft gear with the dowel pin fitted in the groove "a" in the same gear. 2. Install: • Bearing "1" Install the bearing by pressing its outer race parallel. 3.

  • Page 131: Cdi Magneto

    CDI MAGNETO CDI MAGNETO REMOVING THE CDI MAGNETO Order Part name Q'ty Remarks Refer to "SEAT, FUEL TANK AND Seat and fuel tank SIDE COVERS" section. Bolt (Radiator) Refer to "RADIATOR" section. Disconnect the CDI magneto lead. Left crankcase cover Nut (rotor) Refer to removal section.
  • Page 132 CDI MAGNETO REMOVING THE ROTOR CHECKING THE CDI MAGNETO 1. Remove: 1. Inspect: • Nut (rotor) "1" • Rotor inner surface "a" • Washer "2" • Stator outer surface "b" Use the rotor holding tool "3". Damage→Inspect the crankshaft runout and crankshaft bearing.
  • Page 133 CDI MAGNETO 2. Install: 5. Tighten: • Woodruff key "1" • Screw (stator) "1" • Rotor "2" Screw (stator): 7 Nm (0.7 m•kg, 5.1 ft•lb) • Clean the tapered portions of the crankshaft and rotor. • When installing the woodruff key, make sure that its flat surface "a"...

  • Page 134: Engine Removal

    ENGINE REMOVAL ENGINE REMOVAL REMOVING THE ENGINE 26 Nm (2.6 m kg, 19 ft lb) 34 Nm (3.4 m kg, 24 ft lb) 5 Nm (0.5 m kg, 3.6 ft lb) 64 Nm (6.4 m kg, 46 ft lb) 64 Nm (6.4 m kg, 46 ft lb) 85 Nm (8.5 m kg, 61 ft lb) 75 Nm (7.5 m kg, 54 ft lb) Order...
  • Page 135 ENGINE REMOVAL 26 Nm (2.6 m kg, 19 ft lb) 34 Nm (3.4 m kg, 24 ft lb) 5 Nm (0.5 m kg, 3.6 ft lb) 64 Nm (6.4 m kg, 46 ft lb) 64 Nm (6.4 m kg, 46 ft lb) 85 Nm (8.5 m kg, 61 ft lb) 75 Nm (7.5 m kg, 54 ft lb) Order...
  • Page 136 ENGINE REMOVAL HANDLING NOTE Support the machine securely so there is no danger of it falling over. REMOVING THE DRIVE SPROCKET 1. Remove: • Nut (drive sprocket) "1" • Lock washer "2" 2. Remove: • Straighten the lock washer tab. •...
  • Page 137 ENGINE REMOVAL 2. Install: • Lock washer "1" • Nut (drive sprocket) "2" Nut (drive sprocket): 75 Nm (7.5 m•kg, 54 ft•lb) Tighten the nut while applying the rear brake. INSTALLING THE BRAKE PEDAL 1. Install: • Spring "1" • Brake pedal "2" •...

  • Page 138: Crankcase And Crankshaft

    CRANKCASE AND CRANKSHAFT CRANKCASE AND CRANKSHAFT REMOVING THE CRANKSHAFT 30 Nm (3.0 m kg, 22 ft lb) 10 Nm (1.0 m kg, 7.2 ft lb) 14 Nm (1.4 m kg, 10 ft lb) 20 Nm (2.0 m kg, 14 ft lb) Order Part name Q'ty...
  • Page 139 CRANKCASE AND CRANKSHAFT 30 Nm (3.0 m kg, 22 ft lb) 10 Nm (1.0 m kg, 7.2 ft lb) 14 Nm (1.4 m kg, 10 ft lb) 20 Nm (2.0 m kg, 14 ft lb) Order Part name Q'ty Remarks Bolt [L=75 mm (2.95 in)] Holder Crankcase (right)
  • Page 140 CRANKCASE AND CRANKSHAFT REMOVING THE SEGMENT 1. Remove: • Bolt (segment) "1" • Segment "2" Turn the segment counterclockwise until it stops and loosen the bolt. If the segment gets an impact, it may be REMOVING THE CRANKSHAFT damaged. Take care not to give an impact to 1.
  • Page 141 CRANKCASE AND CRANKSHAFT 3. Inspect: • Oil seal "1" Damage → Replace. CHECKING THE CRANKSHAFT 1. Measure: • Runout limit "a" • Small end free play limit "b" • Connecting rod big end side clearance "c" • Crank width "d" Out of specification →...
  • Page 142 CRANKCASE AND CRANKSHAFT INSTALLING THE CRANKSHAFT 1. Install: • Crankshaft "1" Use the crankshaft installing tool "2", "3", "4". Crankshaft installing pot "2": YU-90050/90890-01274 Crankshaft installing bolt "3": YU-90050/90890-01275 Adapter "4": INSTALLING THE CRANKCASE BEARING YU-90063/90890-01278 1. Install: • Bearing "1" •...
  • Page 143 • Apply molybdenum disulfide grease to the surface "a" where the crankshaft and bearing come in contact. 3. Apply: • Use two plain washers (Yamaha genuine: • Sealant 90201-243K3) "5" or the ones of a size as On the right crankcase "1".
  • Page 144 CRANKCASE AND CRANKSHAFT (1.77 1.97 in) • When installing the segment onto the shift cam "3", align the punch mark "a" with the dowel pin "b". • Turn the segment clockwise until it stops and tighten the bolt. (0.98 1.50 in) If the segment gets an impact, it may be (0.16 0.20 in) damaged.

  • Page 145: Transmission, Shift Cam And Shift Fork

    TRANSMISSION, SHIFT CAM AND SHIFT FORK TRANSMISSION, SHIFT CAM AND SHIFT FORK REMOVING THE TRANSMISSION, SHIFT CAM AND SHIFT FORK 10 Nm (1.0 m kg, 7.2 ft lb) 10 Nm (1.0 m kg, 7.2 ft lb) Order Part name Q'ty Remarks Refer to "ENGINE REMOVAL"...
  • Page 146 TRANSMISSION, SHIFT CAM AND SHIFT FORK REMOVING THE TRANSMISSION CHECKING THE BEARING 1. Remove: 1. Inspect: • Main axle "1" • Bearing "1" • Drive axle "2" Rotate inner race with a finger. Rough spot/seizure → Replace. • Tap lightly on the transmission drive axle with a soft hammer to remove.
  • Page 147 TRANSMISSION, SHIFT CAM AND SHIFT FORK 3. Check: 2. Install: • Shift fork movement • 2nd wheel gear (29T) "1" On its guide bar. • 5th wheel gear (24T) "2" Unsmooth operation → Replace shift fork • 3rd wheel gear (27T) "3" and/or guide bar.
  • Page 148 TRANSMISSION, SHIFT CAM AND SHIFT FORK INSTALLING THE SHIFT CAM AND SHIFT FORK 1. Install: • Shift fork 1 (L) "1" • Shift fork 2 (C) "2" • Shift fork 3 (R) "3" • Mesh the shift fork #1 (L) with the 5th wheel gear "4"...
  • Page 149 TRANSMISSION, SHIFT CAM AND SHIFT FORK 2. Install: • Shift cam "1" • Apply the transmission oil on the shift cam. • Install the shift cam while holding up the 5th wheel gear "2" and keeping the shift fork #1 "3"...
  • Page 150 This section is intended for those who have basic knowledge and skill concerning the servicing of Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.) Those who have little knowl- edge and skill concerning servicing are requested not to undertake inspection, adjustment, disas- sembly, or reassembly only by reference to this manual.

  • Page 151: Front Wheel And Rear Wheel

    FRONT WHEEL AND REAR WHEEL FRONT WHEEL AND REAR WHEEL REMOVING THE FRONT WHEEL Order Part name Q'ty Remarks Hold the machine by placing the suit- Refer to "HANDLING NOTE". able stand under the engine. Bolt (axle holder) Only loosening. Nut (front wheel axle) Front wheel axle Front wheel...
  • Page 152 FRONT WHEEL AND REAR WHEEL REMOVING THE REAR WHEEL Order Part name Q'ty Remarks Hold the machine by placing the suit- Refer to "HANDLING NOTE". able stand under the engine. Nut (rear wheel axle) Rear wheel axle Drive chain puller Rear wheel Refer to removal section.
  • Page 153 FRONT WHEEL AND REAR WHEEL HANDLING NOTE Support the machine securely so there is no danger of it falling over. REMOVING THE REAR WHEEL 1. Remove: • Wheel "1" Push the wheel forward and remove the drive 2. Inspect: chain "2". •...
  • Page 154 FRONT WHEEL AND REAR WHEEL CHECKING THE BRAKE DISC eter of the race of the bearing. 1. Measure: • Left side of bearing shall be installed first. • Brake disc deflection (only rear brake disc) • Install the oil seal with its manufacture's Use the dial gauge "1".
  • Page 155 FRONT WHEEL AND REAR WHEEL 3. Install: 6. Install: • Collar "1" • Nut (wheel axle) "1" Nut (wheel axle): • Apply the lithium soap base grease on the oil 105 Nm (10.5 m•kg, 75 ft•lb) seal lip. • Install the collars with their projections "a" fac- ing the wheel.
  • Page 156 FRONT WHEEL AND REAR WHEEL INSTALLING THE REAR WHEEL 1. Install: • Bearing (right) "1" • Circlip "2" • Spacer "3" • Bearing (left) "4" • Oil seal "5" • Apply the lithium soap base grease on the bearing and oil seal lip when installing. 3.
  • Page 157 FRONT WHEEL AND REAR WHEEL 5. Install: 8. Install: • Wheel • Right drive chain puller "1" • Washer "2" • Nut (wheel axle) "3" Install the brake disc "1" between the brake pads "2" correctly. Temporarily tighten the nut (wheel axle) at this point.

  • Page 158: Front Brake And Rear Brake

    FRONT BRAKE AND REAR BRAKE FRONT BRAKE AND REAR BRAKE REMOVING THE FRONT BRAKE Order Part name Q'ty Remarks Hold the machine by placing the suit- Refer to "HANDLING NOTE". able stand under the engine. Drain the brake fluid. Refer to removal section. Brake hose holder (protector) Union bolt Brake hose...
  • Page 159 FRONT BRAKE AND REAR BRAKE REMOVING THE REAR BRAKE Order Part name Q'ty Remarks Hold the machine by placing the suit- Refer to "HANDLING NOTE". able stand under the engine. Refer to "FRONT WHEEL AND Rear wheel REAR WHEEL" section. Drain the brake fluid.
  • Page 160 FRONT BRAKE AND REAR BRAKE DISASSEMBLING THE BRAKE CALIPER Order Part name Q'ty Remarks A. Front B. Rear Pad pin Brake pad Pad support Brake caliper piston 1 Refer to removal section. Brake caliper piston dust seal 1 Refer to removal section. Brake caliper piston seal 1 Refer to removal section.
  • Page 161 FRONT BRAKE AND REAR BRAKE DISASSEMBLING THE BRAKE MASTER CYLINDER Order Part name Q'ty Remarks A. Front B. Rear Brake master cylinder cap Diaphragm Reservoir float Push rod (Front) Brake master cylinder boot Circlip Use a long nose circlip pliers. Washer Push rod (Rear) Brake master cylinder kit...
  • Page 162 FRONT BRAKE AND REAR BRAKE HANDLING NOTE 3. Loosen the bleed screw and drain the brake fluid while pulling the lever in or pushing down on the pedal. Support the machine securely so there is no danger of it falling over. •...
  • Page 163 FRONT BRAKE AND REAR BRAKE REMOVING THE BRAKE CALIPER PISTON SEAL KIT 1. Remove: • Brake caliper piston dust seal "1" • Brake caliper piston seal "2" Remove the brake caliper piston seals and brake caliper piston dust seals by pushing them with a finger.
  • Page 164 FRONT BRAKE AND REAR BRAKE CHECKING THE BRAKE CALIPER HANDLING NOTE 1. Inspect: • Brake caliper cylinder inner surface "a" • All internal parts should be cleaned in new Wear/score marks → Replace brake caliper brake fluid only. assembly. • Internal parts should be lubricated with brake fluid when installed.
  • Page 165 FRONT BRAKE AND REAR BRAKE • Install the brake pads with their projections "a" into the brake caliper recesses "b". • Temporarily tighten the pad pin at this point. A. Front B. Rear 3. Install: • Brake caliper piston "1" 2.
  • Page 166 FRONT BRAKE AND REAR BRAKE INSTALLING THE BRAKE MASTER CYLINDER KIT 1. Clean: • Brake master cylinder • Brake master cylinder kit Clean them with brake fluid. 2. Install: • Brake master cylinder cup (primary) "1" • Brake master cylinder cup (secondary) "2" To brake master cylinder piston "3".
  • Page 167 FRONT BRAKE AND REAR BRAKE INSTALLING THE FRONT BRAKE MASTER CYLINDER 1. Install: • Brake master cylinder "1" • Brake master cylinder bracket "2" • Bolt (brake master cylinder bracket) "3" Bolt (brake master cylinder brack- et): 9 Nm (0.9 m•kg, 6.5 ft•lb) 4.
  • Page 168 FRONT BRAKE AND REAR BRAKE INSTALLING THE REAR BRAKE MASTER CYLINDER 1. Install: • Copper washer "1" • Brake hose "2" • Union bolt "3" Union bolt: 30 Nm (3.0 m•kg, 22 ft•lb) 3. Install: Always use new copper washers. •...
  • Page 169 FRONT BRAKE AND REAR BRAKE INSTALLING THE FRONT BRAKE HOSE 1. Install: • Copper washer "1" • Brake hose "2" • Union bolt "3" Union bolt: 30 Nm (3.0 m•kg, 22 ft•lb) Always use new copper washers. 3. Pass the brake hose through the cable guide "1".
  • Page 170 FRONT BRAKE AND REAR BRAKE After installing the brake hose holders, make sure the brake hose does not contact the spring (rear shock absorber). If it does, correct its twist. INSTALLING THE REAR BRAKE HOSE 1. Install: • Copper washer "1" •...
  • Page 171 FRONT BRAKE AND REAR BRAKE Brake fluid may erode painted surfaces or After installation, while pulling the brake le- plastic parts. Always clean up spilled fluid ver in or pushing down on the brake pedal, immediately. check whether there is any brake fluid leak- ing where the union bolts are installed re- spectively at the brake master cylinder and brake caliper.

  • Page 172: Front Fork

    FRONT FORK FRONT FORK REMOVING THE FRONT FORK Order Part name Q'ty Remarks Hold the machine by placing the suit- Refer to "HANDLING NOTE". able stand under the engine. Refer to "FRONT WHEEL AND Front wheel REAR WHEEL" section. Refer to "FRONT BRAKE AND Front brake caliper REAR BRAKE"...
  • Page 173 FRONT FORK DISASSEMBLING THE FRONT FORK 30 Nm (3.0 m kg, 22 ft lb) 29 Nm (2.9 m kg, 21 ft lb) 1 Nm (0.1 m kg, 0.7 ft lb) 29 Nm (2.9 m kg, 21 ft lb) 55 Nm (5.5 m kg, 40 ft lb) Order Part name Q'ty...
  • Page 174 FRONT FORK HANDLING NOTE REMOVING THE ADJUSTER 1. Drain the outer tube of its front fork oil at its top. Support the machine securely so there is no 2. Loosen: danger of it falling over. • Adjuster "1" The front fork requires careful attention. So it is recommended that the front fork be maintained at the dealers.
  • Page 175 FRONT FORK 2. Remove: CHECKING THE DAMPER ASSEMBLY • Inner tube "1" 1. Inspect: • Damper assembly "1" Bend/damage → Replace. Oil seal removal steps: • O-ring "2" a. Push in slowly "a" the inner tube just before Wear/damage → Replace. it bottoms out and then pull it back quickly "b".
  • Page 176 FRONT FORK Inner tube bending limit: 0.2 mm (0.008 in) The bending value is shown by one half of the dial gauge reading. Do not attempt to straighten a bent inner tube as this may dangerously weaken the CHECKING THE COLLAR tube.
  • Page 177 FRONT FORK 5. Measure: ASSEMBLING THE FRONT FORK • Oil level (left and right) "a" 1. Wash the all parts in a clean solvent. Out of specification → Adjust. 2. Stretch the damper assembly fully. 3. Fill: Standard oil level: •...
  • Page 178 FRONT FORK 7. Loosen: Cap bolt wrench: • Compression damping adjuster "1" YM-01500/90890-01500 Cap bolt ring wrench: • Loosen the compression damping adjuster YM-01501/90890-01501 finger tight. • Record the set position of the adjuster (the amount of turning out the fully turned in posi- tion).
  • Page 179 FRONT FORK 13.Allow the overflowing oil to escape at the hole "a" in the damper assembly. 16.Install: • Piston metal "1" 14.Check: • Damper assembly smooth movement Install the piston metal onto the slot on inner Tightness/binding/rough spots → Repeat tube.
  • Page 180 FRONT FORK 18.Install: 20.Install: • Slide metal "1" • Stopper ring "1" • Oil seal washer "2" To outer tube slot. Fit the stopper ring correctly in the groove in the outer tube. Press the slide metal into the outer tube with fork seal driver "3".
  • Page 181 FRONT FORK 23.Measure: • Distance "a" Out of specification → Turn into the locknut. Distance "a": 16 mm (0.63 in) or more Between the damper assembly "1" bottom and locknut "2" bottom. 26.Loosen: • Rebound damping adjuster "1" • Loosen the rebound damping adjuster finger tight.
  • Page 182 FRONT FORK 28.Inspect: To inner tube. • Gap "a" between the adjuster "1" and lock- nut "2". Out of specification → Retighten and read- just the locknut. Gap "a" between the adjuster and locknut: 0.5–1.0 mm (0.02–0.04 in) If the adjuster is installed out of specification, proper damping force cannot be obtained.
  • Page 183 FRONT FORK 32.Install: • Damper assembly "1" Use the cap bolt ring wrench "2" to tighten the To outer tube. damper assembly with specified torque. Temporarily tighten the damper assembly. Cap bolt ring wrench: YM-01501/90890-01501 33.Install: 3. Adjust: • Protector guide "1" •...
  • Page 184 FRONT FORK 4. Tighten: • Pinch bolt (upper bracket) "1" Pinch bolt (upper bracket): 21 Nm (2.1 m•kg, 15 ft•lb) • Pinch bolt (lower bracket) "2" Pinch bolt (lower bracket): 21 Nm (2.1 m•kg, 15 ft•lb) Tighten the lower bracket to specified 7.

  • Page 185: Handlebar

    HANDLEBAR HANDLEBAR REMOVING THE HANDLEBAR 1 Nm (0.1 m kg, 0.7 ft lb) 9 Nm (0.9 m kg, 6.5 ft lb) 28 Nm (2.8 m kg, 20 ft lb) 4 Nm (0.4 m kg, 2.9 ft lb) 4 Nm (0.4 m kg, 2.9 ft lb) 40 Nm (4.0 m kg, 29 ft lb) 4 Nm (0.4 m kg, 2.9 ft lb) Order...
  • Page 186 HANDLEBAR DISASSEMBLING THE THROTTLE Order Part name Q'ty Remarks Grip cap (lower) Grip cap (upper) Grip assembly Grip (right) Refer to removal section. Tube guide 5-37...
  • Page 187 HANDLEBAR REMOVING THE BRAKE MASTER CYLINDER 1. Remove: • Brake master cylinder bracket "1" • Brake master cylinder "2" • Do not let the brake master cylinder hang on the brake hose. • Keep the brake master cylinder cap side horizontal to prevent air from coming in.
  • Page 188 HANDLEBAR 2. Install: • Grip cap (upper) "1" • Grip cap (lower) "2" • Bolt (grip cap) "3" Temporarily tighten the bolts (grip cap). 2. Install: • Handlebar "1" • Handlebar upper holder "2" • Bolt (handlebar upper holder) "3" Bolt (handlebar upper holder): 28 Nm (2.8 m•kg, 20 ft•lb) INSTALLING THE HANDLEBAR...
  • Page 189 HANDLEBAR 5. Install: • Collar "1" • Grip cap cover "2" • Throttle grip "3" • Apply the lithium soap base grease on the throttle grip sliding surface. • Tighten the grip cap bolts temporarily without the throttle being fixed to the handlebar. 3.
  • Page 190 HANDLEBAR 7. Install: 11.Install: • Roller "1" • Brake master cylinder "1" • Collar "2" • Brake master cylinder bracket "2" • Bolt (brake master cylinder bracket) "3" • Apply the lithium soap base grease on the Bolt (brake master cylinder bracket): roller sliding surface and cable guide.
  • Page 191 HANDLEBAR 15.Adjust: 13.Install: • Clutch lever free play • Engine stop switch "1" • Clutch lever holder "2" Refer to "ADJUSTING THE CLUTCH CA- • Bolt (clutch lever holder) "3" BLE FREE PLAY" section in the CHAPTER Bolt (clutch lever holder): 4 Nm (0.4 m•kg, 2.9 ft•lb) •...

  • Page 192: Steering

    STEERING STEERING REMOVING THE STEERING Order Part name Q'ty Remarks TIGHTENING STEPS: • Tighten ring nut. 38 Nm (3.8 m•kg, 27 ft•lb) • Loosen it one turn. • Retighten it. 7 Nm (0.7 m•kg, 5.1 ft•lb) Hold the machine by placing the suit- Refer to "HANDLING NOTE".
  • Page 193 STEERING Order Part name Q'ty Remarks Steering ring nut Refer to removal section. Lower bracket Bearing race cover Upper bearing Lower bearing Refer to removal section. Bearing race Refer to removal section. 5-44...
  • Page 194 STEERING HANDLING NOTE Support the machine securely so there is no danger of it falling over. REMOVING THE STEERING RING NUT 1. Remove: • Steering ring nut "1" Use the steering nut wrench "2". Steering nut wrench: CHECKING THE STEERING STEM YU-33975/90890-01403 1.
  • Page 195 STEERING 4. Install: INSTALLING THE LOWER BRACKET • Steering ring nut "1" 1. Install: • Lower bearing "1" Steering ring nut: 7 Nm (0.7 m•kg, 5.1 ft•lb) Apply the lithium soap base grease on the dust Tighten the steering ring nut using the steer- seal lip and bearing inner circumference.
  • Page 196 STEERING 7. Install: 11.Tighten: • Front fork "1" • Pinch bolt (upper bracket) "1" • Upper bracket "2" Pinch bolt (upper bracket): 21 Nm (2.1 m•kg, 15 ft•lb) • Temporarily tighten the pinch bolts (lower • Pinch bolt (lower bracket) "2" bracket).

  • Page 197: Swingarm

    SWINGARM SWINGARM REMOVING THE SWINGARM Order Part name Q'ty Remarks Hold the machine by placing the suit- Refer to "HANDLING NOTE". able stand under the engine. Refer to "FRONT BRAKE AND Brake hose holder REAR BRAKE" section. Refer to "FRONT BRAKE AND Rear brake caliper REAR BRAKE"...
  • Page 198 SWINGARM DISASSEMBLING THE SWINGARM 70 Nm (7.0 m kg, 50 ft lb) 2 Nm (0.2 m kg, 1.4 ft lb) 6 Nm (0.6 m kg, 4.3 ft lb) 80 Nm (8.0 m kg, 58 ft lb) Order Part name Q'ty Remarks Refer to removal section.
  • Page 199 SWINGARM HANDLING NOTE Support the machine securely so there is no danger of it falling over. REMOVING THE CAP 1. Remove: • Left cap "1" Remove with a slotted-head screwdriver insert- CHECKING THE RELAY ARM ed under the mark "a" on the left cap. 1.
  • Page 200 SWINGARM INSTALLING THE BEARING AND OIL SEAL 1. Install: • Bearing "1" • Oil seal "2" To swingarm. • Apply the molybdenum disulfide grease on the bearing when installing. • Install the bearing by pressing it on the side having the manufacture's marks or numbers. •...
  • Page 201 SWINGARM INSTALLING THE SWINGARM 1. Install: • Bushing "1" • Thrust bearing "2" • Oil seal "3" • Collar "4" To swingarm "5". Apply the molybdenum disulfide grease on the bushings, thrust bearings, oil seal lips and con- 4. Install: tact surfaces of the collar and thrust bearing.
  • Page 202 SWINGARM 6. Install: • Swingarm "1" • Pivot shaft "2" Pivot shaft: 85 Nm (8.5 m•kg, 61 ft•lb) • Apply the molybdenum disulfide grease on the pivot shaft. • Insert the pivot shaft from right side. 9. Install: • Bolt (rear shock absorber-relay arm) "1" •...
  • Page 203 SWINGARM 11.Tighten: 14.Install: • Nut (relay arm) "1" • Drive chain support "1" • Drive chain support cover "2" Nut (relay arm): • Bolt {drive chain support [L = 50 mm (1.97 70 Nm (7.0 m•kg, 50 ft•lb) in)]} "3" •...

  • Page 204: Rear Shock Absorber

    REAR SHOCK ABSORBER REAR SHOCK ABSORBER REMOVING THE REAR SHOCK ABSORBER 56 Nm (5.6 m kg, 40 ft lb) 2 Nm (0.2 m kg, 1.4 ft lb) 32 Nm (3.2 m kg, 23 ft lb) 29 Nm (2.9 m kg, 21 ft lb) 53 Nm (5.3 m kg, 38 ft lb) Order Part name...
  • Page 205 REAR SHOCK ABSORBER 56 Nm (5.6 m kg, 40 ft lb) 2 Nm (0.2 m kg, 1.4 ft lb) 32 Nm (3.2 m kg, 23 ft lb) 29 Nm (2.9 m kg, 21 ft lb) 53 Nm (5.3 m kg, 38 ft lb) Order Part name Q'ty...
  • Page 206 "1". Wear eye protection to prevent eye damage from escaping gas and/or metal chips. To dispose of a damaged or worn-out rear shock absorber, take the unit to your Yamaha dealer for this disposal procedure. 5-57...
  • Page 207 REAR SHOCK ABSORBER 3. Remove: • Lower bearing "1" Remove the bearing by pressing its outer race. INSTALLING THE BEARING 1. Install: • Upper bearing "1" Install the bearing parallel until the stopper ring CHECKING THE REAR SHOCK ABSORBER groove appears by pressing its outer race. 1.
  • Page 208 REAR SHOCK ABSORBER 3. Install: 3. Tighten: • Lower bearing "1" • Adjuster "1" Install the bearing by pressing it on the side having the manufacture's marks or numbers. Installed depth of the bearing "a": 4 mm (0.16 in) 4. Adjust: •...
  • Page 209 REAR SHOCK ABSORBER 2. Install: • Bushing "1" • Collar "2" • Dust seal "3" • Apply the molybdenum disulfide grease on the bearing and dust seal lips. • Install the dust seals with their lips facing out- ward. 6. Install: •...
  • Page 210 This section is intended for those who have basic knowledge and skill concerning the servicing of Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.) Those who have little knowl- edge and skill concerning servicing are requested not to undertake inspection, adjustment, disas- sembly, or reassembly only by reference to this manual.
  • Page 211 ELECTRICAL COMPONENTS AND WIRING DIAGRAM ELECTRICAL COMPONENTS AND WIRING DIAGRAM ELECTRICAL COMPONENTS 1. Engine stop switch 4. CDI magneto 2. CDI unit 5. Spark plug 3. Ignition coil...

  • Page 212: Electrical Components And Wiring Diagram

    ELECTRICAL COMPONENTS AND WIRING DIAGRAM WIRING DIAGRAM 1. Engine stop switch 2. CDI unit 3. Ignition coil 4. CDI magneto 5. Spark plug COLOR CODE Black Orange Yellow Black/Red B/W Black/White Green/Blue G/W Green/White White/Blue W/R White/Red...
  • Page 213 IGNITION SYSTEM IGNITION SYSTEM INSPECTION STEPS Use the following steps for checking the possibility of the malfunctioning engine being attributable to ignition system failure and for checking the spark plug which will not spark. Spark gap test Spark → *Clean or replace spark plug. No spark ↓...
  • Page 214 IGNITION SYSTEM SPARK GAP TEST CHECKING THE ENGINE STOP SWITCH 1. Disconnect the spark plug cap from spark 1. Inspect: plug. • Engine stop switch conduction 2. Connect the dynamic spark tester "1" (igni- Tester (+) lead → Black/White lead "1" tion checker "2") as shown.
  • Page 215 IGNITION SYSTEM 2. Inspect: • Secondary coil resistance Out of specification → Replace. Tester (+) lead → Spark plug lead "1" Tester (-) lead → Yellow lead "2" Secondary coil Tester selector resistance position 5.7–8.5 kΩat 20 kΩ × 1 °C (68 °F) CHECKING THE CDI MAGNETO 1.
  • Page 216 IGNITION SYSTEM 3. Inspect: • Charging coil 2 resistance Out of specification → Replace. Tester (+) lead → Green/Blue lead "1" Tester (-) lead → Black lead "2" Charging coil 2 Tester selector resistance position 44–66 Ω at 20 °C Ω...

  • Page 217: Tuning

    ENGINE TUNING the same air. • Lower atmospheric pressure (at a high alti- ENGINE tude) reduces the density of the air. CARBURETOR SETTING TEST RUN • The role of fuel is to cool the engine, and in After warming up the engine equipped with the the case of a 2-stroke engine, to lubricate the standard type carburetor(s) and spark plug(s), engine in addition to power generation.
  • Page 218 ENGINE EFFECT OF SETTING PARTS IN RELATION TO THROTTLE VALVE OPENING ADJUSTING THE PILOT AIR SCREW The richness of the air-fuel mixture with full closed to 1/4 throttle can be set by turning the pilot air screw "1". Turning in the pilot air screw will enrich the mixture at low speeds, and turn- ing out it will lean out the mixture.
  • Page 219 ENGINE ADJUSTING THE JET NEEDLE GROOVE In the case of the same number of clip position, POSITION changing from 6BFY42-74 to 6BFY43-74 has Should the engine be hard to run smoothly at the same effect as a rising of 0.5-clip position. intermediate speeds, the jet needle "1"...
  • Page 220 ENGINE 6BFY42-74-3 6BFY42-74-2 6BFY42-75-3 (For EUROPE, AUS, NZ and ZA) 6BFY43-73 6BFY43-74 6BFY43-75 6BFY43-74-3 6BFY43-74-2 6BFY43-75-3 A. Lean (larger diameter) 6BFY44-74 B. Rich (smaller diameter) C. 1st taper D. 2nd taper E. 3rd taper 6BFY43-74 F. 4th taper 1. Full closed 2.
  • Page 221 ENGINE CARBURETOR SETTING PARTS Part name Size Part number Rich 6BFY43 284-14116-J2 Part name Size Part number Main jet Rich #470 137-14143-94 6BFY43 284-14116-J3 "1" #460 137-14143-92 **(STD) 6BFY43 284-14116-J4 #450 137-14143-90 #440 137-14143-88 6BFY43 284-14116-J5 **(STD) #430 137-14143-86 #420 137-14143-84 Lean 6BFY43 284-14116-J6...
  • Page 222 ENGINE ROAD CONDITION AND EXAMPLES OF CARBURETOR SETTING General condition Sandy condition Under 10°C 15–25°C Over 30°C Under 10°C 15–25°C Over 30°C (50°F) (59–77°F) (86°F) (50°F) (59–77°F) (86°F (Winter) (Spring, Au- (Summer) (Winter) (Spring, Au- (Summer) tumn) tumn) Main jet #420 #410 #410...
  • Page 223 ENGINE EXAMPLES OF CARBURETOR SETTING DEPENDING ON SYMPTOM Symptom Setting Checking At full throttle Increase main jet calibration no. Discoloration of spark plug → If tan Stall at high speeds (Gradually) color, it is in good condition. *Hard breathing If cannot be corrected: Shearing noise Clogged float valve seat Whitish spark plug...
  • Page 224 ENGINE Symptom Setting Checking Poor response when Check overall settings. Check air filter for fouling. throttle is opened quickly Use main jet having lower calibra- tion no. Raise jet needle clip position. (1 groove up) If no effect, reverse the above pro- cedures.
  • Page 225 ENGINE CHANGE OF THE HEAT RANGE OF SPARK PLUGS Judging from the discoloration of spark plugs, if they are found improper, it can be corrected by the following two methods; changing carburetor settings and changing the heat range of spark plug.
  • Page 226 CHASSIS CHASSIS DRIVE AND REAR WHEEL SPROCKETS SETTING PARTS SELECTION OF THE SECONDARY REDUCTION RATIO (SPROCKET) Part name Size Part number Drive sprocket "1" Secondary reduction ratio = Number of rear wheel sprocket teeth/Number of (STD) 9383B-13218 drive sprocket teeth Rear wheel sprocket "2"...
  • Page 227 CHASSIS • Under a stony or hard road condition, the tire pressure should be higher to prevent a flat tire. Extent of adjustment: 100–120 kPa (1.0–1.2 kgf/cm , 15– 18 psi) FRONT FORK SETTING The front fork setting should be made depend- ing on the rider's feeling of an actual run and the circuit conditions.
  • Page 228 CHASSIS REAR SUSPENSION SETTING Generally a stiff spring gives a stiff riding feel- The rear suspension setting should be made ing. Rebound damping tends to become weak- depending on the rider's feeling of an actual run er, resulting in lack of a sense of contact with and the circuit conditions.
  • Page 229 CHASSIS Length "a" of standard shock: • If the machine is new and after it is broken in, 490 mm (19.29 in) the same set length of the spring may change because of the initial fatigue, etc. of the spring. Therefore, be sure to make reevalua- tion.
  • Page 230 CHASSIS REAR SHOCK ABSORBER SETTING • The unequal-pitch spring is softer in initial PARTS characteristic than the equal-pitch spring and • Rear shock spring "1" is difficult to bottom out under full compres- [Equal-pitch titanium spring] sion. SPRING PART I.D. •...
  • Page 231 CHASSIS SUSPENSION SETTING (FRONT FORK) • If any of the following symptoms is experienced with the standard position as the base, make reset- ting by reference to the adjustment procedure given in the same chart. • Before any change, set the rear shock absorber sunken length to the standard figure 90–100 mm (3.5–3.9 in).
  • Page 232 CHASSIS SUSPENSION SETTING (REAR SHOCK ABSORBER) • If any of the following symptoms is experienced with the standard position as the base, make reset- ting by reference to the adjustment procedure given in the same chart. • Adjust the rebound damping in 2-click increments or decrements. •...
  • Page 234 YAMAHA MOTOR CO., LTD. PRINTED ON RECYCLED PAPER PRINTED IN JAPAN 2008.4—0.4 × 1 ! 2500 SHINGAI IWATA SHIZUOKA JAPAN...

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