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Yamaha YZ125 2019 Owner's Service Manual

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2019
OWNER'S SERVICE MANUAL
YZ125
Read this manual carefully before operating this vehicle.
YZ125K2
LIT-11626-32-19
B0V-28199-10

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Summary of Contents for Yamaha YZ125 2019

  • Page 1 2019 OWNER’S SERVICE MANUAL YZ125 Read this manual carefully before operating this vehicle. YZ125K2 LIT-11626-32-19 B0V-28199-10...
  • Page 2 Operating, servicing and maintaining a passenger vehicle or off-road vehicle can expose you to chemicals including engine exhaust, carbon monoxide, phthalates, and lead, which are known to the State of California to cause cancer and birth defects or other reproductive harm. To minimize exposure, avoid breathing exhaust, do not idle the engine except as necessary, service your vehicle in a well-ventilated area and wear gloves or wash your...
  • Page 3 YZ125K2 OWNER'S SERVICE MANUAL ©2019 by Yamaha Motor Corporation, U.S.A. 1st Edition, April 2018 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-11626-32-19...
  • Page 4 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 • 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 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 8 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 9 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 10 MEMO...

  • Page 11: Table Of Contents

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

  • Page 12: General Information

    CONTENTS CHAPTER 1 GENERAL INFORMATION LOCATION OF IMPORTANT LABELS ..1-1 DESCRIPTION ........... 1-2 CONSUMER INFORMATION ....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: Engine

    CHAPTER 4 ENGINE SEAT, FUEL TANK AND SIDE  COVERS ............ 4-1 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: Tuning

    CHAPTER 7 TUNING ENGINE ............7-1 CHASSIS............ 7-9...
  • Page 15 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 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 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 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 sides- tand.
  • Page 19 5. Keep away from fire. ALL REPLACEMENT PARTS 2. Use proper tools and cleaning equipment. 1. We recommend to use Yamaha genuine Refer to "SPECIAL TOOLS" section. parts for all replacements. Use oil and/or grease recommended by Yamaha for as- sembly and adjustment.
  • Page 20 IMPORTANT INFORMATION LOCK WASHERS/PLATES AND COTTER CIRCLIPS PINS 1. All circlips should be inspected carefully be- 1. All lock washers/plates "1" and cotter pins fore reassembly. Always replace piston pin must be replaced when they are removed. clips after one use. Replace distorted cir- Lock tab(s) should be bent along the bolt or clips.
  • Page 21 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 The proper special tools are necessary for complete and accurate tune-up and assembly. Using the correct special tool will help prevent damage caused by the use of improper tools or improvised tech- niques. The shape and part number used for the special tool differ by country, so two types are pro- vided.
  • Page 23 SPECIAL TOOLS Tool name/Part number How to use Illustration Fuel level gauge "1" This gauge is used to mea- YM-01312-A, 90890-01312 sure the fuel level in the float Fuel level gauge adapter "2" chamber. YM-01470, 90890-01470 Radiator cap tester These tools are used for YU-24460-A, 90890-01325 checking the cooling system.
  • 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 90890-85505 for crankcase mating surface, (Three bond No. 1215®) etc. 1-10...
  • Page 25 CONTROL FUNCTIONS CONTROL FUNCTIONS KICKSTARTER LEVER Rotate the kickstarter lever "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 Never mix two types of oil in the same ELEMENT" section in the CHAPTER 3, apply the Yamaha foam air filter oil or other quality batch; clotting of the oil could result. If you foam air filter oil to the element. (Excess oil in...
  • Page 28 STARTING AND BREAK-IN BREAK-IN PROCEDURES 1. Before starting the engine, fill the fuel tank • After the break-in or before each race, you with a break-in oil-fuel mixture as follows. must check the entire machine for loose Mixing oil: fittings and fasteners as per "TORQUE- YAMALUBE "2-R"...
  • Page 29 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 MAINTENANCE AFTER BREAK-IN MAINTENANCE AFTER BREAK-IN • Cable Grease and adjust cables. After a break-in, perform careful maintenance • Drive chain to get ready for the next practice or race. Lubricate the drive chain and adjust its ten- Refer to "PRE-OPERATION INSPECTION sion.
  • Page 31 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 32 GENERAL SPECIFICATIONS SPECIFICATIONS GENERAL SPECIFICATIONS Model name: YZ125K2 (USA) YZ125K (CAN, AUS, NZ, ZA) YZ125 (EUROPE) Model code number: B0V1 (USA, CAN) B0V2 (EUROPE) B0V4 (AUS, NZ, ZA) Dimensions: Overall length 2,135 mm (84.1 in) Overall width 825 mm (32.5 in) Overall height 1,295 mm (51.0 in) Seat height...
  • Page 33 GENERAL SPECIFICATIONS Clutch type: Wet, multiple-disc Transmission: Primary reduction system Gear Primary reduction ratio 3.368 (64/19) Final drive Chain Secondary reduction ratio 3.692 (48/13) Transmission type Constant mesh, 6-speed Operation Left foot operation Gear ratio: 2.385 (31/13) 1.933 (29/15) 1.588 (27/17) 1.353 (23/17) 1.200 (24/20) 1.095 (23/21)
  • Page 34 MAINTENANCE SPECIFICATIONS MAINTENANCE SPECIFICATIONS ENGINE Item Standard Limit Cylinder head: Combustion chamber volume 8.30–8.50 cm (0.51–0.52 cu.in) ---- Warp limit ---- 0.03 mm (0.0012 in) Cylinder: Bore size 54.000–54.014 mm (2.1260–2.1265 in) 54.100 mm (2.1299 in) Taper limit ---- 0.050 mm (0.0020 in) Out of round limit ----...
  • Page 35 0.050 mm (0.0020 in) Kickstarter type: Kick and mesh ---- Kick clip friction force P=7.80–11.80 N (0.80–1.20 kg, 1.75– ---- 2.65 lb) Air filter oil grade (oiled filter): Yamaha foam air filter oil or other quality ---- foam air filter oil...
  • Page 36 MAINTENANCE SPECIFICATIONS Item Standard Limit Carburetor: USA, CAN EUROPE AUS, NZ, ZA ← ← Type/Manufacturer TMXχ38SS /MIKUNI ← I.D. mark 1C37 51 1C36 41 ---- ← ← Main jet (M.J.) #430 ---- ← ← Jet needle-clip position (J.N.) 6BFY43-74- ---- ←...
  • Page 37 ---- Optional spring ---- Oil capacity 510.0 cm (17.99 Imp oz, 17.24 US oz) ---- Oil grade Yamaha Suspension Oil S1 ---- Inner tube outer diameter 48 mm (1.9 in) ---- Front fork top end 5 mm (0.2 in) ----...
  • Page 38 MAINTENANCE SPECIFICATIONS Item Standard Limit Drive chain: Type DID520DMA4K SDH ---- Number of links ---- Chain slack 48.0–58.0 mm (1.89–2.28 in) ---- Chain length (15 links) ---- 242.8 mm (9.56 in) Front disc brake: Disc outside dia.×Thickness 270.0 × 3.0 mm (10.63 × 0.12 in) 270.0 ×...
  • Page 39 44.0–66.0 Ωat 20 °C (68 °F) Charging coil 2 resistance (color) ---- (Black-Green/Blue) 248.0–372.0 Ωat 20 °C (68 °F) Pickup coil resistance (color) ---- (White/Blue-White/Red) CDI unit-model/manufacturer 1C3-10/YAMAHA (USA, CAN) ---- 1SR-00/YAMAHA (EUROPE, AUS, ZA, NZ) Ignition coil: Model/manufacturer 1C3-00/YAMAHA ---- Minimum spark gap 6.0 mm (0.24 in)
  • Page 40 TIGHTENING TORQUES TIGHTENING TORQUES ENGINE △ - marked portion shall be checked for torque tightening after break-in or before each race. Threa Item Q'ty Tightening torque Remarks d size Spark plug M14S 20 Nm (2.0 m•kg, 14 ft•lb) Copper Cylinder head (nut) 28 Nm (2.8 m•kg, 20 ft•lb) washer Cylinder head (stud)
  • Page 41 TIGHTENING TORQUES Threa Item Q'ty Tightening torque Remarks d size Holder 10 Nm (1.0 m•kg, 7.2 ft•lb) Copper Oil check bolt 10 Nm (1.0 m•kg, 7.2 ft•lb) washer Copper Oil drain bolt 20 Nm (2.0 m•kg, 14 ft•lb) washer Kickstarter lever 10 Nm (1.0 m•kg, 7.2 ft•lb) Clutch cover 10 Nm (1.0 m•kg, 7.2 ft•lb)
  • Page 42 TIGHTENING TORQUES CHASSIS △ - marked portion shall be checked for torque tightening after break-in or before each race. Threa Item Q'ty Tightening torque Remarks d size △ Upper bracket and outer tube 21 Nm (2.1 m•kg, 15 ft•lb) △ Lower bracket and outer tube 21 Nm (2.1 m•kg, 15 ft•lb) △...
  • Page 43 TIGHTENING TORQUES Threa Item Q'ty Tightening torque Remarks d size △ Brake caliper (front and rear) and 18 Nm (1.8 m•kg, 13 ft•lb) pad pin △ Brake caliper (front and rear) and 6 Nm (0.6 m•kg, 4.3 ft•lb) bleed screw △...
  • Page 44 TIGHTENING TORQUES Threa Item Q'ty Tightening torque Remarks d size △ Swingarm and brake hose holder 3 Nm (0.3 m•kg, 2.2 ft•lb) Swingarm and patch 2 Nm (0.2 m•kg, 1.4 ft•lb) Drive chain tensioner 16 Nm (1.6 m•kg, 11 ft•lb) Drive chain support and swingarm 7 Nm (0.7 m•kg, 5.1 ft•lb) Seal guard and swingarm...
  • Page 45 TIGHTENING TORQUES GENERAL TORQUE SPECIFICATIONS This chart specifies torque for standard fasten- ers with standard I.S.O. pitch threads. Torque specifications for special components or as- semblies are included in the applicable sec- tions of this book. To avoid warpage, tighten multi-fastener assemblies in a crisscross fash- ion, in progressive stages, until full torque is reached.
  • Page 46 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 47 TIGHTENING TORQUES 2-16...
  • Page 48 CABLE ROUTING DIAGRAM CABLE ROUTING DIAGRAM 2-17...
  • Page 49 CABLE ROUTING DIAGRAM 1. Engine stop switch lead N. Tighten the clamp with its bolt head facing 2. Throttle cable the left side of the chassis (on both sides of 3. Clutch cable the carburetor joint and the air filter joint). 4.
  • Page 50 CABLE ROUTING DIAGRAM 2-19...
  • Page 51 CABLE ROUTING DIAGRAM 1. High tension cord 2. Engine stop switch lead 3. Ignition coil lead 4. Clamp 5. CDI unit 6. CDI unit band 7. Joint connector 8. Radiator breather hose 9. CDI magneto lead 10. Connector cover 11. Throttle cable 12.
  • Page 52 CABLE ROUTING DIAGRAM 2-21...
  • Page 53 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 54 CABLE ROUTING DIAGRAM 2-23...
  • Page 55 CABLE ROUTING DIAGRAM 1. Brake hose 2. Master cylinder 3. Engine stop switch lead 4. Engine stop switch 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 56 If you are a doubt as to what intervals to follow in maintaining and lubricating your machine, consult your Yamaha dealer. • Periodic inspection is essential in making full use of the machine performance. The service life of the parts varies substantially according to the environment in which the machine runs (e.g., rain,...
  • Page 57 MAINTENANCE INTERVALS Every Every Every After race third fifth As re- Item break Remarks (about (about (about quired 12.5 hours) hours) hours) TRANSMISSION ● ● Replace oil Recommended brand: YAMA- LUBE SAE 10W-40 API service SG type or higher JASO standard MA ●...
  • Page 58 Retighten Refer to "STARTING AND BREAK-IN" section in the CHAPTER 1. AIR FILTER ● ● Clean and lubricate Use the Yamaha foam air filter oil or other quality foam air filter ● Replace FRAME ● ● Clean and inspect FUEL TANK, COCK ●...
  • Page 59 ● ● 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 60 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 61 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 62 ENGINE CHECKING THE RADIATOR CAP 1. Inspect: • Do not mix more than one type of ethylene • Seal (radiator cap) "1" glycol antifreeze containing corrosion in- • Valve and valve seat "2" hibitors for aluminum engine. Crack/damage → Replace. •...
  • Page 63 ENGINE CHECKING THE COOLING SYSTEM ADJUSTING THE CLUTCH LEVER 1. Inspect: POSITION • Coolant level 1. Adjust: 2. Attach: • Clutch lever position • Radiator cap tester "1" and adapter "2" Clutch lever position adjustment steps: Radiator cap tester: a. Loosen the locknuts "1". YU-24460-A/90890-01325 b.
  • Page 64 ENGINE 2. Adjust: ADJUSTING THE THROTTLE GRIP FREE • Clutch lever free play PLAY 1. Check: • Throttle grip free play "a" Handlebar side Out of specification → Adjust. a. Turn the adjuster "1" until the specified clutch lever free play is obtained. Throttle grip free play "a": 3.0–5.0 mm (0.12–0.20 in) If the clutch lever free play cannot be obtained...
  • Page 65 Damage → Replace. Throttle cable cap: 4. Apply: 0.5 Nm (0.05 m•kg, 0.36 ft•lb) • Yamaha foam air filter oil or other quality foam air filter oil • Cap cover CLEANING THE AIR FILTER ELEMENT Squeeze out the excess oil. Element should be wet but not dripping.
  • Page 66 ENGINE 5. Install: CHECKING THE TRANSMISSION OIL • Air filter guide "1" LEVEL 1. Start the engine, warm it up for several min- utes and wait for five minutes. Align the projection "a" on filter guide with the 2. Place the machine on a level place and hold hole "b"...
  • Page 67 ENGINE CHANGING THE TRANSMISSION OIL 8. Check: 1. Start the engine and warm it up for several • Transmission oil level minutes and wait for five minute. 9. Install: 2. Place the machine on a level place and hold • Oil filler cap "2" it on upright position by placing the suitable ADJUSTING THE PILOT AIR SCREW stand under the engine.
  • Page 68 ENGINE CHECKING THE EXHAUST PIPE 1. Inspect: • O-ring "1" Damage → Replace. Install the O-rings with their depressed "a" fac- ing outward. 3-13...
  • Page 69 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 70 CHASSIS 2. Remove: 2. Adjust: • Brake lever cover • Brake pedal height 3. Adjust: • Brake lever position Pedal height adjustment steps: a. Loosen the locknut "1". Brake lever position adjustment steps: b. Turn the adjusting nut "2" until the pedal a.
  • Page 71 CHASSIS 2. Replace: f. Loosen the bleed screw and push the brake • Brake pad caliper pistons 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 72 CHASSIS j. Install the pad pin plug "10". 2. Replace: • Brake pad Pad pin plug: 3 Nm (0.3 m•kg, 2.2 ft•lb) Brake pad replacement steps: a. Remove the protector "1" and pad pin plug "2". 3. Inspect: • Brake fluid level b.
  • Page 73 CHASSIS k. Install the pad pin plug "15" and protector "16". Pad pin plug: 3 Nm (0.3 m•kg, 2.2 ft•lb) Bolt (protector): 7 Nm (0.7 m•kg, 5.1 ft•lb) f. Loosen the bleed screw and push the brake caliper piston in. Do not reuse the drained brake fluid.
  • Page 74 CHASSIS CHECKING THE BRAKE FLUID LEVEL CHECKING THE DRIVE CHAIN 1. Place the brake master cylinder so that its 1. Measure: top is in a horizontal position. • Drive chain length (15 links) "a" Out of specification → Replace. 2. Inspect: •...
  • Page 75 CHASSIS 6. Lubricate: • Drive chain Drive chain lubricant: SAE 10W-40 motor oil or suitable chain lubricants 4. Check: • Drive chain stiffness "a" Clean and oil the drive chain and hold as il- lustrated. Stiff → Replace the drive chain. ADJUSTING THE DRIVE CHAIN SLACK 1.
  • Page 76 CHASSIS 3. Adjust: • Drive chain slack Drive chain slack adjustment steps: a. Loosen the axle nut "1" and locknuts "2". b. Adjust the drive chain slack by turning the adjusters "3". To tighten → Turn the adjuster "3" counter- clockwise.
  • Page 77 CHASSIS 2. Clean: ADJUSTING THE FRONT FORK REBOUND • Dust seal "a" DAMPING FORCE • Oil seal "b" 1. Adjust: • Rebound damping force By turning the adjuster "1". • Clean the dust seal and oil seal after every run. Stiffer "a"...
  • Page 78 CHASSIS ADJUSTING THE FRONT FORK COMPRESSION DAMPING FORCE 1. Adjust: • Compression damping force By turning the adjuster "1". Stiffer "a" → Increase the compression damping force. (Turn the adjuster "1" in.) Softer "b" → Decrease the compression damping force. (Turn the adjuster "1" out.) ADJUSTING THE REAR SHOCK ABSORBER SPRING PRELOAD...
  • Page 79 CHASSIS 4. Adjust: • Rear frame (lower) • Spring preload Rear frame (lower): 29 Nm (2.9 m•kg, 21 ft•lb) Adjustment steps: ADJUSTING THE REAR SHOCK a. Loosen the locknut "1". ABSORBER REBOUND DAMPING FORCE b. Loosen the adjuster "2" until there is some 1.
  • Page 80 CHASSIS ADJUSTING THE REAR SHOCK ADJUSTING THE REAR SHOCK ABSORBER LOW COMPRESSION ABSORBER HIGH COMPRESSION DAMPING FORCE DAMPING FORCE 1. Adjust: 1. Adjust: • Low compression damping force • High compression damping force By turning the adjuster "1". By turning the adjuster "1". Stiffer "a"...
  • Page 81 CHASSIS CHECKING THE TIRE PRESSURE 2. Tighten: 1. Measure: • Spoke • Tire pressure (with a spoke nipple wrench "1") Out of specification → Adjust. Be sure to tighten the spokes before and after Standard tire pressure: break-in. 100 kPa (1.00 kgf/cm , 15 psi) •...
  • Page 82 CHASSIS CHECKING AND ADJUSTING THE STEERING HEAD 1. Place a stand under the engine to raise the front wheel off the ground. WARNING! Se- curely support the vehicle so that there is no danger of it falling over. 2. Check: •...
  • Page 83 CHASSIS h. Install the washer "5", upper bracket "6", washer "7", steering stem nut "8", handlebar "9", upper handlebar holders "10" and num- ber plate "11". • The upper handlebar holders should be in- stalled with the punch marks "a" facing for- ward.
  • Page 84 CHASSIS LUBRICATION 3-29...
  • Page 85 8. Throttle roller sliding surface 9. Tube guide cable winding portion 10. Throttle cable end 11. Clutch cable end A. Use Yamaha cable lube or equivalent on these areas. B. Use SAE 10W-40 motor oil or suitable chain lubricants. C. Lubricate the following areas with high quality, lightweight lithium-soap base grease.
  • Page 86 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 87 ELECTRICAL 4. Set the dial gauge to zero at TDC. 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.): 0.50 mm (0.02 in) 6. Check: •...
  • Page 88 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 89 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) 10 Nm (1.0 m kg, 7.2 ft lb) 19 Nm (1.9 m kg, 13 ft lb)
  • Page 90 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 backward to remove it be- cause its claws "a" are inserted in the air filter case.
  • Page 91 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 92 4. Install: • Inner pipe ® Fully apply Quick gasket (Yamaha bond No.1215) or equivalent as shown. Yamaha bond No. 1215: 90890-85505 (Three bond No. 1215®) 5. Install: • Bolt (fiber) "1" Bolt (fiber): 10 Nm (1.0 m•kg, 7.2 ft•lb) •...
  • Page 93 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 94 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 95 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 96 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 97 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 98 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 99 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 100 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 101 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 102 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 103 CARBURETOR AND REED VALVE INSTALLING THE CARBURETOR 4. Adjust: 1. Install: • Idle speed • Carburetor "1" Refer to "ADJUSTING THE ENGINE 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 104 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 105 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 106 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 107 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 108 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 109 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.
  • Page 110 CYLINDER HEAD, CYLINDER AND PISTON CHECKING THE PISTON CLEARANCE 1. Calculate: • Piston clearance Out of specification → Replace piston, and piston ring and/or cylinder. Refer to "Cylinder" and "Piston". PISTON CLEARANCE = CYLINDER BORE - PISTON DIAMETER Piston clearance: 3.
  • Page 111 CYLINDER HEAD, CYLINDER AND PISTON CHECKING THE POWER VALVE HOLE ON CYLINDER • Install the spring to the link lever, and then to 1. Remove: the cylinder. • Carbon deposits • Install the spring with its stopper portion "a" From power valve hole surface "a". facing inward.
  • Page 112 CYLINDER HEAD, CYLINDER AND PISTON 5. Install: 2. Install: • Gasket (power valve cover) "1" • Gasket (cylinder) "1" • Power valve cover "2" • Small end bearing "2" • Screw (power valve cover) "3" • Dowel pin "3" Screw (power valve cover): •...
  • Page 113 CYLINDER HEAD, CYLINDER AND PISTON 3. Install: • Nut (cylinder) "1" Nut (cylinder): 30 Nm (3.0 m•kg, 22 ft•lb) Tighten the nuts in stage, using a crisscross pattern. INSTALLING THE CYLINDER HEAD AND CYLINDER 1. Apply: • Engine oil To piston "1", piston ring "2" and cylinder surface.
  • Page 114 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 115 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 116 CLUTCH REMOVING THE CLUTCH BOSS 80 Nm (8.0 kg m) 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 117 CLUTCH REMOVING THE CLUTCH BOSS CHECKING THE PRIMARY DRIVEN GEAR 1. Remove: 1. Check: • Circumferential play • Nut "1" Free play exists → Replace. • Lock washer "2" • Gear teeth "a" • Clutch boss "3" Wear/damage → Replace. Straighten the lock washer tab and use the clutch holding tool "4"...
  • Page 118 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 119 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 120 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 121 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 122 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 123 KICK SHAFT AND SHIFT SHAFT REMOVING THE PRIMARY DRIVE GEAR REMOVING THE SEGMENT 1. Loosen: 1. Remove: • Bolt (primary drive gear) "1" • Bolt (segment) "1" • Segment "2" Place an aluminum plate "a" between the teeth of the primary drive gear "2" and driven gear Turn the segment counterclockwise until it "3".
  • Page 124 KICK SHAFT AND SHIFT SHAFT CHECKING THE KICK GEAR CLIP CHECKING THE STOPPER LEVER 1. Measure: 1. Inspect: • Kick clip friction force • Stopper lever "1" Out of specification → Replace. Wear/damage → Replace. Use a spring gauge "1". •...
  • Page 125 KICK SHAFT AND SHIFT SHAFT INSTALLING THE SEGMENT 1. Install: • Segment "1" • Bolt (segment) Bolt (segment): 30 Nm (3.0 m•kg, 22 ft•lb) Align the notch "a" on the segment with the pin "b" on the shift cam. INSTALLING THE SHIFT GUIDE AND SHIFT LEVER ASSEMBLY If the segment gets an impact, the stopper 1.
  • Page 126 KICK SHAFT AND SHIFT SHAFT 4. Install: 2. Install: • Bolt (shift guide) "1" • Spring guide "1" Bolt (shift guide): Slide the spring guide into the kick shaft, make 10 Nm (1.0 m•kg, 7.2 ft•lb) sure the groove "a" in the spring guide fits on the stopper of the torsion spring.
  • Page 127 KICK SHAFT AND SHIFT SHAFT 3. Tighten: • Bolt (primary drive gear) "1" Bolt (primary drive gear): 48 Nm (4.8 m•kg, 35 ft•lb) Place an aluminum plate "a" between the teeth of the primary drive gear and driven gear. INSTALLING THE KICK IDLE GEAR 1.
  • Page 128 KICK SHAFT AND SHIFT SHAFT 6. Install: • Bolt [crankcase cover (right)] "1" Bolt [crankcase cover (right)]: 10 Nm (1.0 m•kg, 7.2 ft•lb) Tighten the bolts in stage, using a crisscross pattern. 7. Install: • Kickstarter "1" • Plain washer "2" •...
  • Page 129 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 130 YPVS GOVERNOR REMOVING THE GOVERNOR INSTALLING THE GOVERNOR 1. Remove: 1. Install: • Dowel pin "1" • Governor gear "1" • Compression spring "2" • Plate "3" While compressing the spring, remove the • Washer "4" dowel pin. • Thrust bearing "5" •...
  • Page 131 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 132 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 133 WATER PUMP REMOVING THE OIL SEAL • Replace the oil seal when transmission oil or coolant leaks out from the water pump hous- ing hole at the bottom. • Do not reuse the removed bearing and oil seal. 1. Remove: •...
  • Page 134 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 135 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 136 CDI MAGNETO REMOVING THE ROTOR 1. Remove: • Nut (rotor) "1" • Washer "2" Use the rotor holding tool "3". Rotor holding tool: YU-01235/90890-01235 CHECKING THE WOODRUFF KEY 1. Inspect: • Woodruff key "1" Damage → Replace. 2. Remove: • Rotor "1" Use the flywheel puller "2".
  • Page 137 CDI MAGNETO 2. Install: • Woodruff key "1" • Rotor "2" • Clean the tapered portions of the crankshaft and rotor. • When installing the woodruff key, make sure that its flat surface "a" is in parallel with the crankshaft center line "b". •...
  • Page 138 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 139 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 140 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 141 ENGINE REMOVAL • Nut [engine mounting bolt (upper)] "12" INSTALLING THE DRIVE SPROCKET 1. Install: Nut [engine mounting bolt (upper)]: • Drive sprocket "1" 34 Nm (3.4 m•kg, 24 ft•lb) • Drive chain "2" Apply the molybdenum disulfide grease on the Install the drive sprocket together with the drive pivot shaft.
  • Page 142 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 143 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 144 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, the stopper REMOVING THE CRANKSHAFT lever may be damaged. Take care not to 1.
  • Page 145 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 146 CRANKCASE AND CRANKSHAFT INSTALLING THE CRANKSHAFT 1. Install: • Crankshaft "1" Use the crankshaft installing tools "2", "3", "4". Crankshaft installer pot "2": YU-90058/90890-01274 Crankshaft installer bolt "3": YU-90060/90890-01275 Adapter (M12) "4": INSTALLING THE CRANKCASE BEARING YU-90063/90890-01278 1. Install: • Bearing "1" •...
  • Page 147 • 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 148 CRANKCASE AND CRANKSHAFT 8. Install: • Segment "1" • Bolt (segment) "2" Bolt (segment): 30 Nm (3.0 m•kg, 22 ft•lb) • When installing the segment onto the shift cam "3", align the punch mark "a" with the dowel pin "b". •...
  • Page 149 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 150 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 151 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 152 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 153 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" moved in the direction of the arrow.
  • Page 154 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 155 FRONT WHEEL AND REAR WHEEL Order Part name Q'ty Remarks Bearing Refer to removal section. Brake disc...
  • Page 156 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 157 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 158 FRONT WHEEL AND REAR WHEEL CHECKING THE BRAKE DISC • Use a socket that matches the outside diam- 1. Measure: eter of the race of the bearing. • Brake disc deflection (only rear brake disc) • Left side of bearing shall be installed first. Use the dial gauge "1".
  • Page 159 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 160 FRONT WHEEL AND REAR WHEEL • Apply the lithium soap base grease on the bearing and oil seal lip when installing. • Install the bearing with seal facing outward. • Use a socket that matches the outside diam- eter of the race of the bearing. •...
  • Page 161 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 162 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 163 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 164 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 165 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 166 FRONT BRAKE AND REAR BRAKE HANDLING NOTE • Do not reuse the drained brake fluid. Support the machine securely so there is no • Brake fluid may erode painted surfaces or danger of it falling over. plastic parts. Always clean up spilled fluid immediately.
  • Page 167 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 168 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 169 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 170 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 171 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 172 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 173 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 174 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 175 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 176 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 177 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 178 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 179 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 180 FRONT FORK Inner tube bending limit: 0.2 mm (0.01 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 181 3. Fill: assembly. • Front fork oil "1" To damper assembly. Recommended oil: Yamaha Suspension Oil S1 Oil capacity: 205 cm (7.21 Imp oz, 6.93 US oz) • Be sure to use recommended fork oil. If other oils are used, they may have an ex- cessively adverse effect on the front fork performance.
  • Page 182 FRONT FORK 8. Install: 11.After filling, pump the damper assembly "1" • Base valve "1" slowly up and down more than 10 times to To damper assembly "2". distribute the fork oil. First bring the damper rod pressure to a maxi- mum.
  • Page 183 FRONT FORK 14.Check: 16.Install: • Damper assembly smooth movement • Piston metal "1" Tightness/binding/rough spots → Repeat the steps 2 to 13. Install the piston metal onto the slot on inner tube. 15.Install: • Dust seal "1" 17.Install: • Stopper ring "2" •...
  • Page 184 FRONT FORK 21.Install: • Dust seal "1" Apply the lithium soap base grease on the inner tube. 19.Install: • Oil seal "1" Press the oil seal into the outer tube with fork seal driver "2". 22.Check: Fork seal driver: • Inner tube smooth movement YM-A0948/90890-01502 Tightness/binding/rough spots →...
  • Page 185 FRONT FORK 26.Loosen: • Rebound damping adjuster "1" • Loosen the rebound damping adjuster finger tight. • Record the set position of the adjuster (the amount of turning out the fully turned in posi- tion). 24.Install: • Collar "1" • Fork spring "2" To damper assembly "3".
  • Page 186 • Front fork oil "1" If the adjuster is installed out of specification, From outer tube top. proper damping force cannot be obtained. Recommended oil: Yamaha Suspension Oil S1 Standard oil amount: 315 cm (11.1 Imp oz, 10.7 US oz) Extent of adjustment: 300–365 cm...
  • Page 187 FRONT FORK 33.Install: 3. Adjust: • Protector guide "1" • Front fork top end "a" Front fork top end (standard) "a": 5 mm (0.2 in) INSTALLING THE FRONT FORK 1. Install: • Front fork "1" 4. Tighten: • Pinch bolt (upper bracket) "1" •...
  • Page 188 FRONT FORK 6. Adjust: • Rebound damping force Turn in the damping adjuster "1" finger-tight and then turn out to the originally set position. 7. Adjust: • Compression damping force Turn in the damping adjuster "1" finger-tight and then turn out to the originally set position. 5-35...
  • Page 189 HANDLEBAR HANDLEBAR REMOVING THE HANDLEBAR 0.5 Nm (0.05 m kg, 0.36 ft lb) 9 Nm (0.9 m kg, 6.5 ft lb) 28 Nm (2.8 m kg, 20 ft lb) 5 Nm (0.5 m kg, 3.6 ft lb) 4 Nm (0.4 m kg, 2.9 ft lb) 0.5 Nm (0.05 m kg, 0.36 ft lb) 40 Nm (4.0 m kg, 29 ft lb) 4 Nm (0.4 m kg, 2.9 ft lb)
  • Page 190 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 191 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 192 HANDLEBAR 2. Install: • Handlebar "1" • Upper handlebar holder "2" • Bolt (upper handlebar holder) "3" Bolt (upper handlebar holder): 28 Nm (2.8 m•kg, 20 ft•lb) • The upper handlebar holders should be in- stalled with the punch marks "a" facing for- ward.
  • Page 193 HANDLEBAR • Tighten the grip cap bolts temporarily without the throttle being fixed to the handlebar. 3. Tighten: • Nut (lower handlebar holder) "1" Nut (lower handlebar holder): 6. Install: 40 Nm (4.0 m•kg, 29 ft•lb) • Throttle cables "1" To tube guide "2".
  • Page 194 HANDLEBAR 8. Install: • Throttle cable cap "1" • Screw (throttle cable cap) "2" Screw (throttle cable cap): 0.5 Nm (0.05 m•kg, 0.36 ft•lb) 12.Install: • Bolt (grip cap) "1" Bolt (grip cap): 4 Nm (0.4 m•kg, 2.9 ft•lb) 9. Adjust: •...
  • Page 195 HANDLEBAR • The engine stop switch, clutch lever holder and clamp should be installed according to the dimensions shown. • Pass the engine stop switch lead in the middle of the clutch lever holder. 0 mm (0 in) 0 mm (0 in) 14.Install: •...
  • Page 196 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 197 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 198 STEERING HANDLING NOTE REMOVING THE BEARING RACE 1. Remove: • Bearing race "1" Support the machine securely so there is no Remove the bearing race using long rod "2" danger of it falling over. and the hammer. REMOVING THE STEERING RING NUT 1.
  • Page 199 STEERING INSTALLING THE LOWER BRACKET 4. Install: 1. Install: • Steering ring nut "1" • 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 200 STEERING 7. Install: 10.Adjust: • Front fork "1" • Front fork top end "a" • Upper bracket "2" Front fork top end (standard) "a": 5 mm (0.2 in) • Temporarily tighten the pinch bolts (lower bracket). • Do not tighten the pinch bolts (upper bracket) yet.
  • Page 201 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 202 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 203 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 204 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 205 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- tact surfaces of the collar and thrust bearing. 4.
  • Page 206 SWINGARM • Apply the molybdenum disulfide grease on the bolt. • Do not tighten the nut yet. 6. Install: • Swingarm "1" • Pivot shaft "2" Pivot shaft: 85 Nm (8.5 m•kg, 61 ft•lb) 9. Install: • Bolt (rear shock absorber-relay arm) "1" •...
  • Page 207 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 208 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 209 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 210 "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 211 REAR SHOCK ABSORBER CHECKING THE REAR SHOCK ABSORBER 1. Inspect: • Damper rod "1" Bends/damage → Replace rear shock ab- sorber assembly. • Shock absorber "2" Oil leaks → Replace rear shock absorber as- sembly. Gas leaks → Replace rear shock absorber assembly.
  • Page 212 REAR SHOCK ABSORBER INSTALLING THE SPRING (REAR SHOCK INSTALLING THE REAR SHOCK ABSORBER) ABSORBER 1. Install: 1. Install: • Spring "1" • Dust seal "1" • Upper spring guide "2" • O-ring "2" • Lower spring guide "3" • Collar "3" •...
  • Page 213 REAR SHOCK ABSORBER 4. Install: • Bolt (rear shock absorber-frame) "1" • Washer "2" • Nut (rear shock absorber-frame) "3" Nut (rear shock absorber-frame): 56 Nm (5.6 m•kg, 40 ft•lb) Apply the molybdenum disulfide grease on the bolt. 7. Tighten: •...
  • Page 214 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 215 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 216 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 → Spark gap test *Clean or replace spark plug. No spark ↓...
  • Page 217 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 218 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 5.68–8.52 kΩat kΩ × 1 20 °C (68 °F) CHECKING THE CDI MAGNETO 1.
  • Page 219 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 44.0–66.0 Ω at Ω × 10 20 °C (68 °F) CHECKING THE CDI UNIT Check all electrical components.
  • Page 220 ENGINE TUNING • Lower atmospheric pressure (at a high alti- tude) reduces the density of the air. ENGINE TEST RUN CARBURETOR SETTING After warming up the engine equipped with the • The role of fuel is to cool the engine, and in standard type carburetor(s) and spark plug(s), the case of a 2-stroke engine, to lubricate the run two or three laps of the circuit and check the...
  • Page 221 ENGINE EFFECT OF SETTING PARTS IN RELATION ADJUSTING THE PILOT AIR SCREW TO THROTTLE VALVE OPENING 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 222 ENGINE ADJUSTING THE JET NEEDLE GROOVE ADJUSTING THE JET NEEDLE POSITION On the carburetors used in the YZ125, the main Should the engine be hard to run smoothly at nozzle is a non disassembly type, so it can not intermediate speeds, the jet needle "1" must be be replaced.
  • Page 223 ENGINE RELATIONSHIP WITH THROTTLE OPENING CARBURETOR SETTING PARTS The flow of the fuel through the carburetor main Part name Size Part number system is controlled by the main jet and then, it Main jet Rich #470 137-14143-94 is further regulated by the area between the "1"...
  • Page 224 ENGINE Part name Size Part number Rich 6BFY43 284-14116-J2 6BFY43 284-14116-J3 (STD) 6BFY43 284-14116-J4 6BFY43 284-14116-J5 Lean 6BFY43 284-14116-J6 Rich 6BFY42 284-14116-H2 6BFY42 284-14116-H3 6BFY42 284-14116-H4 6BFY42 284-14116-H5 Lean 6BFY42 284-14116-H6 * For USA and CAN ** Except for USA and CAN...
  • Page 225 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 #440 #430 #420...
  • Page 226 ENGINE Symptom Setting Checking Lean mixture Lower jet needle clip position. (1 Groove 1 Clip groove down) Groove 2 Groove 3 Rich mixture Raise jet needle clip position. (1 Leaner Groove 4 Groove 5 groove up) (Standard) 1/4–3/4 throttle Lower jet needle clip position. (1 *Hard breathing groove down) Richer...
  • Page 227 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 228 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 229 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 (1.00–1.20 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 230 CHASSIS 2. Use of stiff spring REAR SUSPENSION SETTING • Change the rebound damping. The rear suspension setting should be made Turn in one or two clicks. depending on the rider's feeling of an actual run • Change the compression damping. and the circuit conditions.
  • Page 231 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 232 CHASSIS • Extent of adjustment (spring preload) SPRING PART Maximum Minimum NUMBER (-22212-) 5UN-00 5UN-10 5UN-20 5UN-30 5UN-40 Position in Position in 5UN-50 which the which the 5UN-60 spring is spring is 5UN-70 turned in 18 turned in 1.5 mm (0.71 in) mm (0.06 in) 5UN-A0 from its free...
  • Page 233 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 234 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 235 For your best ownership experience, think Genuine Yamaha! Genuine Yamaha Parts – Genuine Yamaha replacement parts are the exact same parts as the ones originally equipped on your vehicle, providing you with the performance and durability you have come to expect.
  • Page 236 PRINTED ON RECYCLED PAPER PRINTED IN JAPAN 2018.04-0.4×1 !

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Yz125k2 2019