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Yamaha YZ250F(R) Owner's Service Manual

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OWNER'S SERVICE MANUAL
YZ250FR
5UL-28199-10
LIT-11626-16-39

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Summary of Contents for Yamaha YZ250F(R)

  • Page 1 OWNER’S SERVICE MANUAL YZ250FR 5UL-28199-10 LIT-11626-16-39...
  • Page 3 YZ250FR OWNER’S SERVICE MANUAL ©2002 by Yamaha Motor Corporation, U.S.A. 1st Edition, July 2002 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-11626-16-39...
  • Page 4 EC020000 INTRODUCTION Congratulations on your purchase of a Yamaha YZ series. This model is the culmina- tion of Yamaha’s vast experience in the pro- duction of pacesetting racing machines. It represents the highest grade of craftsmanship and reliability that have made Yamaha a leader.

  • Page 6: Important Notice

    IMPORTANT NOTICE THIS MACHINE IS DESIGNED STRICTLY FOR COMPETITION USE, ONLY ON A CLOSED COURSE. It is illegal for this machine to be operated on any public street, road, or highway. Off-road use on public lands may also be illegal. Please check local regula- tions before riding.
  • Page 7 6. GASOLINE CAN CAUSE INJURY. If you should swallow some gasoline, inhale excess gasoline vapors, or allow any gasoline to get into your eyes, contact a doctor immediately. If any gasoline spills onto your skin or clothing, immediately wash skin areas with soap and water, and change your clothes.
  • Page 8 If you have any questions regarding the operation or maintenance of your machine, please consult your Yamaha dealer. NOTE: This manual should be considered a perma- nent part of this machine and should remain with it even if the machine is subsequently sold.
  • Page 9 EC080000 HOW TO USE THIS MANUAL EC081000 PARTICULARLY IMPORTANT INFORMATION The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR SAFETY INVOLVED! WARNING Failure to follow WARNING instructions could result in severe injury or death to the machine operator, a bystander, or a person inspecting or repairing the machine.
  • Page 10 EC083000 MANUAL FORMAT All of the procedures in this manual are organized in a sequential, step-by-step format. The informa- tion has been complied to provide the mechanic with an easy to read, handy reference that contains comprehensive explanations of all disassembly, repair, assembly, and inspection operations. In this revised format, the condition of a faulty component will precede an arrow symbol and the course of action required will follow the symbol, e.g., Bearings...
  • Page 11 ILLUSTRATED SYMBOLS (Refer to the illustration) Illustrated symbols 1 to 7 are designed as SPEC INFO thumb tabs to indicate the chapter’s number and content. 1 General information INSP 2 Specifications 3 Regular inspection and adjustments 4 Engine 5 Chassis 6 Electrical 7 Tuning –...
  • Page 12 MEMO...
  • Page 13 EC090000 INDEX GENERAL INFORMATION INFO SPECIFICATIONS SPEC REGULAR INSPECTION AND ADJUSTMENTS INSP ENGINE CHASSIS CHAS – ELECTRICAL ELEC TUNING...

  • Page 14: Table Of Contents

    EC0A0000 CONTENTS CHAPTER 1 GENERAL INFORMATION DESCRIPTION .......... 1-1 MACHINE IDENTIFICATION ....1-2 IMPORTANT INFORMATION ....1-3 CHECKING OF CONNECTION ....1-6 SPECIAL TOOLS ........1-7 CONTROL FUNCTIONS ......1-10 FUEL ............1-13 STARTING AND BREAK-IN ....1-14 TORQUE-CHECK POINTS ..... 1-18 CLEANING AND STORAGE ....
  • Page 15 CHAPTER 4 ENGINE SEAT, FUEL TANK AND SIDE COVERS ......... 4-1 EXHAUST PIPE AND SILENCER .... 4-3 RADIATOR ..........4-5 CARBURETOR ......... 4-8 CAMSHAFTS .......... 4-21 CYLINDER HEAD ........4-30 VALVES AND VALVE SPRINGS ... 4-33 CYLINDER AND PISTON ....... 4-42 CLUTCH ..........
  • Page 16 CHAPTER 6 ELECTRICAL ELECTRICAL COMPONENTS AND WIRING DIAGRAM ......6-1 MAP-CONTROLLED CDI UNIT ....6-2 IGNITION SYSTEM ........6-3 THROTTLE POSITION SENSOR SYSTEM ............ 6-7 CHAPTER 7 TUNING ENGINE ............. 7-1 CHASSIS ..........7-11...

  • Page 17: General Information

    DESCRIPTION INFO EC100000 GENERAL INFORMATION EC110000 DESCRIPTION 1 Clutch lever NOTE: 2 Hot starter lever The machine you have purchased may differ ● 3 Front brake lever slightly from those shown in the following. 4 Throttle grip Designs and specifications are subject to 5 Radiator cap ●...

  • Page 18: Machine Identification

    There are two significant reasons for knowing the serial number of your machine: 1. When ordering parts, you can give the number to your Yamaha dealer for posi- tive identification 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 19: Important Information

    IMPORTANT INFORMATION INFO EC130000 IMPORTANT INFORMATION EC131010 PREPARATION FOR REMOVAL AND DISASSEMBLY 1. Remove all dirt, mud, dust, and foreign material before removal and disassem- bly. When washing the machine with high pressured water, cover the parts follows. Silencer exhaust port ●...
  • Page 20 IMPORTANT INFORMATION INFO EC132000 ALL REPLACEMENT PARTS 1. We recommend to use Yamaha genuine parts for all replacements. Use oil and/or grease recommended by Yamaha for assembly and adjustment. EC133000 GASKETS, OIL SEALS AND O-RINGS 1. All gaskets, oil seals, and O-rings should be replaced when an engine is over- hauled.
  • Page 21 IMPORTANT INFORMATION INFO EC136000 CIRCLIPS 1. All circlips should be inspected carefully before reassembly. Always replace pis- ton pin clips after one use. Replace dis- torted circlips. When installing a circlip 1, make sure that the sharp-edged cor- ner 2 is positioned opposite to the thrust 3 it receives.

  • Page 22: Checking Of Connection

    CHECKING OF CONNECTION INFO EC1C0001 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.

  • Page 23: Special Tools

    SPECIAL TOOLS INFO 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 techniques. The shape and part number used for the special tool differ by country, so two types are provided.
  • Page 24 SPECIAL TOOLS INFO Part number Tool name/How to use Illustration YU-33975, 90890-01403 Steering nut wrench YU-33975 90890-01403 This tool is used when tighten the steering ring nut to specification. YM-1423, 90890-01423 Damper rod holder YM-1423 90890-01423 Use this tool to remove and install the damper rod. YM-01442, 90890-01442 Fork seal driver YM-01442...
  • Page 25 Dynamic spark tester YM-34487 90890-06754 90890-06754 Ignition checker This instrument is necessary for checking the ignition system components.  ACC-QUICK-GS-KT Quick gasket ACC-QUICK-GS-KT 90890-85505 90890-85505 YAMAHA Bond No. 1215 This sealant (Bond) is used for crankcase mating surface, etc. 1 - 9...

  • Page 26: Control Functions

    CONTROL FUNCTIONS INFO EC150000 CONTROL FUNCTIONS ENGINE STOP SWITCH The engine stop switch 1 is located on the left handlebar. Continue pushing the engine stop switch till the engine comes to a stop. EC152000 CLUTCH LEVER The clutch lever 1 is located on the left han- dlebar;...
  • Page 27 CONTROL FUNCTIONS INFO EC156000 FRONT BRAKE LEVER The front brake lever 1 is located on the right handlebar. Pull it toward the handlebar to acti- vate the front brake. EC157000 REAR BRAKE PEDAL The rear brake pedal 1 is located on the right side of the machine.
  • Page 28 CONTROL FUNCTIONS INFO EC15R001 DETACHABLE SIDESTAND This sidestand 1 is used to support only the machine when standing or transporting it. WARNING Never apply additional force to the side- ● stand. Remove this sidestand before starting ● out. EC15F000 VALVE JOINT This valve joint 1 prevents fuel from flowing out and is installed to the fuel tank breather hose.

  • Page 29: Fuel

    FUEL INFO FUEL Always use the recommended fuel as stated below. Also, be sure to use new gasoline the day of a race. Recommended fuel: Except for ZA: Premium unleaded gasoline only with a research octane number of 95 or higher. For ZA: Premium gasoline CAUTION:...

  • Page 30: Starting And Break-In

    STARTING AND BREAK-IN INFO STARTING AND BREAK-IN WARNING Never start or run the engine in a closed area. The exhaust fumes are poisonous; they can cause loss of consciousness and death in a very short time. Always operate the machine in a well-ventilated area. CAUTION: The carburetor on this machine has a ●...
  • Page 31 STARTING AND BREAK-IN INFO 6. Return the cold starter knob to its original position and run the engine at 3,000 ~ 5,000 r/min for 1 or 2 minutes. NOTE: Since this model is equipped with an accelera- tor pump, if the engine is raced (the throttle opened and closed), the air/fuel mixture will be too rich and the engine may stall.
  • Page 32 STARTING AND BREAK-IN INFO STARTING A WARM ENGINE Do not operate the cold starter knob and throt- tle. Pull the hot starter lever 1 and start the engine by kicking the kickstarter crank force- fully with a firm stroke. As soon as the engine starts, Release the hot starter lever to close the air passage.
  • Page 33 STARTING AND BREAK-IN INFO BREAK-IN PROCEDURES 1. Before starting the engine, fill the fuel tank with the fuel. 2. Perform the pre-operation checks on the machine. 3. Start and warm up the engine. Check the idle speed, and check the operation of the controls and the engine stop switch.

  • Page 34: Torque-Check Points

    TORQUE-CHECK POINTS INFO 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 Steering stem to frame Steering stem to upper bracket...

  • Page 35: Cleaning And Storage

    CLEANING AND STORAGE INFO EC1B0000 CLEANING AND STORAGE EC1B1000 CLEANING Frequent cleaning of your machine will enhance its appearance, maintain good over- all performance, and extend the life of many components. 1. Before washing the machine, block off the end of the exhaust pipe to prevent water from entering.
  • Page 36 CLEANING AND STORAGE INFO EC1B2001 STORAGE If your machine is to be stored for 60 days or more, some preventive measures must be taken to avoid deterioration. After cleaning the machine thoroughly, prepare it for storage as follows: 1. Drain the fuel tank, fuel lines, and the carburetor float bowl.

  • Page 37: Specifications

    SPEC GENERAL SPECIFICATIONS EC200000 SPECIFICATIONS EC211000 GENERAL SPECIFICATIONS Model name: YZ250FR (USA) YZ250F (EUROPE) YZ250F(R) (CDN, AUS, NZ, ZA) Model code number: 5UL1 (USA) 5UL2 (EUROPE) 5UL4 (CDN, AUS, NZ, ZA) Dimensions: Overall length 2,165 mm (85.2 in) Overall width 827 mm (32.6 in)
  • Page 38 SPEC GENERAL SPECIFICATIONS Oil capacity: Engine oil Periodic oil change 1.0 L (0.88 Imp qt, 1.06 US qt) With oil filter replacement 1.1 L (0.97 Imp qt, 1.16 US qt) Total amount 1.2 L (1.06 Imp qt, 1.27 US qt) Coolant capacity (including all routes): 0.9 L (0.79 Imp qt, 0.95 US qt) Air filter:...
  • Page 39 SPEC GENERAL SPECIFICATIONS Brake: Front brake type Single disc brake Operation Right hand operation Rear brake type Single disc brake Operation Right foot operation Suspension: Front suspension Telescopic fork Rear suspension Swingarm (link type monocross suspension) Shock absorber: Front shock absorber Coil spring/oil damper Rear shock absorber Coil spring/gas, oil damper...

  • Page 40: Maintenance Specifications

    SPEC MAINTENANCE SPECIFICATIONS MAINTENANCE SPECIFICATIONS ENGINE Item Standard Limit Cylinder head: Warp limit ---- 0.05 mm (0.002 in) Cylinder: Bore size 77.00 ~ 77.01 mm ---- (3.0315 ~ 3.0319 in) Out of round limit ---- 0.05 mm (0.002 in) Camshaft: Drive method Chain drive (Left) ----...
  • Page 41 SPEC MAINTENANCE SPECIFICATIONS Item Standard Limit Timing chain: Timing chain type/No. of links 92RH2010-114M/114 ---- Timing chain adjustment method Automatic ---- Valve, valve seat, valve guide: Valve clearance (cold) 0.10 ~ 0.15 mm ---- (0.0039 ~ 0.0059 in) 0.17 ~ 0.22 mm ---- (0.0067 ~ 0.0087 in) Valve dimensions:...
  • Page 42 SPEC MAINTENANCE SPECIFICATIONS Item Standard Limit Stem runout limit ---- 0.01 mm (0.0004 in) Valve seat width 0.9 ~ 1.1 mm 1.6 mm (0.0354 ~ 0.0433 in) (0.0630 in) 0.9 ~ 1.1 mm 1.6 mm (0.0354 ~ 0.0433 in) (0.0630 in) Valve spring: Free length 37.81 mm (1.49 in)
  • Page 43 SPEC MAINTENANCE SPECIFICATIONS Item Standard Limit Piston pin bore inside diameter 16.002 ~ 16.013 mm 16.043 mm (0.6300 ~ 0.6304 in) (0.6316 in) Piston pin outside diameter 15.991 ~ 16.000 mm 15.971 mm (0.6296 ~ 0.6299 in) (0.6288 in) Piston rings: Top ring: Type Barrel...
  • Page 44 SPEC MAINTENANCE SPECIFICATIONS Item Standard Limit Clutch: Friction plate thickness 2.9 ~ 3.1 mm 2.7 mm (0.114 ~ 0.122 in) (0.106 in) Quantity ---- Clutch plate thickness 1.1 ~ 1.3 mm (0.043 ~ 0.051 in) ---- Quantity ---- Warp limit ---- 0.1 mm (0.004 in)
  • Page 45 SPEC MAINTENANCE SPECIFICATIONS Item Standard Limit Lubrication system: Oil filter type Wire mesh type ---- Oil pump type Trochoid type ---- Tip clearance 0.12 mm or less 0.20 mm (0.0047 in or less) (0.008 in) Side clearance 0.09 ~ 0.17 mm 0.24 mm (0.0035 ~ 0.0067 in) (0.009 in)
  • Page 46 SPEC MAINTENANCE SPECIFICATIONS Tightening torque Part to be tightened Thread size Q’ty m·kg ft·lb M10S × 1.0 Spark plug M6 × 1.0 Camshaft cap M12 × 1.0 Cylinder head blind plug screw M6 × 1.0 Cylinder head (stud bolt) M8 × 1.25 (stud bolt) M9 ×...
  • Page 47 SPEC MAINTENANCE SPECIFICATIONS Tightening torque Part to be tightened Thread size Q’ty m·kg ft·lb M8 × 1.25 Silencer M8 × 1.25 Silencer clamp M6 × 1.0 Crankcase M6 × 1.0 Crankcase bearing stopper M6 × 1.0 Crankcase bearing stopper (crankshaft) M6 ×...
  • Page 48 SPEC MAINTENANCE SPECIFICATIONS CHASSIS Item Standard Limit Steering system: Steering bearing type Taper roller bearing ---- Front suspension: USA, CDN EUROPE AUS, NZ, ZA 300 mm (11.8 in) ← Front fork travel ---- 460 mm (18.1 in) ← Fork spring free length 455 mm (17.9 in) Spring rate, STD K = 4.22 N/mm...
  • Page 49 SPEC MAINTENANCE SPECIFICATIONS Item Standard Limit Wheel: Front wheel type Spoke wheel ---- Rear wheel type Spoke wheel ---- 21 × 1.60/Aluminum Front rim size/material ---- 19 × 1.85/Aluminum Rear rim size/material ---- Rim runout limit: Radial ---- 2.0 mm (0.08 in) Lateral ---- 2.0 mm (0.08 in)
  • Page 50 SPEC MAINTENANCE SPECIFICATIONS Tightening torque Part to be tightened Thread size Q’ty m·kg ft·lb M8 × 1.25 Upper bracket and outer tube M8 × 1.25 Lower bracket and outer tube M24 × 1.0 Upper bracket and steering stem 14.5 M8 × 1.25 Handlebar holder and upper bracket M28 ×...
  • Page 51 SPEC MAINTENANCE SPECIFICATIONS Tightening torque Part to be tightened Thread size Q’ty m·kg ft·lb Nipple (spoke) — M8 × 1.25 Rear wheel sprocket M6 × 1.0 Rear brake disc cover M6 × 1.0 Rear brake caliper protector M8 × 1.25 Drive chain puller adjust bolt and locknut Engine mounting: M10 ×...
  • Page 52 Limit Ignition system: Advancer type Electrical ---- CDI: Magneto-model (stator)/manufac- 5SF-00/YAMAHA ---- turer 720 ~ 1,080 Ω at 20 ˚C (68 ˚F) Charging coil 1 resistance (color) ---- (Green – Brown) 44 ~ 66 Ω at 20 ˚C (68 ˚F)

  • Page 53: General Torque Specifications

    GENERAL TORQUE SPECIFICATIONS/ SPEC DEFINITION OF UNITS EC220001 GENERAL TORQUE SPECIFICATIONS This chart specifies torque for standard fasten- ers with standard I.S.O. pitch threads. Torque specifications for special components or assemblies 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 54: Cable Routing Diagram

    SPEC CABLE ROUTING DIAGRAM EC240000 CABLE ROUTING DIAGRAM 1 Fuel tank breather hose Å Pass the fuel tank breather hose Ï Fasten the neutral switch lead 2 Clutch cable between the handlebar and ten- and CDI magneto lead to the 3 Oil tank breather hose sion bar, then insert its end into cable guide with a plastic locking...
  • Page 55 SPEC CABLE ROUTING DIAGRAM Ò Make sure that the throttle  Pass the carburetor breather position sensor lead coupler hoses and overflow hose so does not go out side the chas- that all there hoses do not con- sis. tact the rear shock absorber. ˜...
  • Page 56 SPEC CABLE ROUTING DIAGRAM 1 CDI unit Å Pass the hot starter cable and Ï First install the CDI unit and 2 Hot starter cable throttle cables through the CDI unit band to the CDI unit 3 Throttle cable (return) cable guides.
  • Page 57 SPEC CABLE ROUTING DIAGRAM 1 Brake master cylinder Å Install the brake hose so that its pipe portion 2 Brake hose holder directs as shown and lightly touches the projection 3 Brake hose on the brake caliper. ı Pass the brake hose into the brake hose holders. Ç...
  • Page 58 SPEC CABLE ROUTING DIAGRAM 1 Throttle cable Å Fasten the engine stop switch lead to the handlebar. 2 Fuel tank breather hose ı Pass the brake hose in front of the number plate. 3 Clamp Ç Pass the clutch cable through the cable guide. 4 Clutch cable Î...

  • Page 59: Regular Inspection And Adjustments

    If you are a doubt as to what intervals to follow in maintaining and lubricating your machine, consult your Yamaha dealer. Every...
  • Page 60 INSP MAINTENANCE INTERVALS Every Every After Every As re- third fifth Item Remarks break-in race quired 500 km) 1,000 km) SHIFT FORK, SHIFT CAM, GUIDE BAR ● Inspect Inspect wear ROTOR NUT ● ● Retighten EXHAUST PIPE, SILENCER, PRO- TECTOR ●...
  • Page 61 Retighten sprocket bolt ● Inspect bearings ● Replace bearings ● Lubricate Lithium base grease THROTTLE, CONTROL CABLE Yamaha cable lube or ● ● Check routing and connection SAE 10W-30 motor oil ● ● Lubricate Inspect dirt and wear on ●...

  • Page 62: Pre-Operation Inspection And Maintenance

    INSP PRE-OPERATION INSPECTION AND MAINTENANCE EC320000 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...

  • Page 63: Engine

    INSP ENGINE/COOLANT LEVEL INSPECTION EC350000 ENGINE COOLANT LEVEL INSPECTION WARNING Do not remove the radiator cap 1, drain bolt and hoses when the engine and radia- tor are hot. Scalding hot fluid and steam may be blown out under pressure, which could cause serious injury.
  • Page 64 INSP COOLANT REPLACEMENT COOLANT REPLACEMENT WARNING Do not remove the radiator cap when the engine is hot. CAUTION: Take care so that coolant does not splash on painted surfaces. If it splashes, wash it away with water. 1. Place a container under the engine. 2.
  • Page 65 INSP RADIATOR CAP INSPECTION CAUTION: Do not mix more than one type of ethyl- ● ene glycol antifreeze containing corro- sion inhibitors for aluminum engine. Do not use water containing impurities or ● oil. Handling notes of coolant: The coolant is harmful so it should be han- dled with special care.
  • Page 66 RADIATOR CAP OPENING PRESSURE INSPECTION/ INSP COOLING SYSTEM INSPECTION RADIATOR CAP OPENING PRESSURE INSPECTION 1. Attach: Radiator cap tester 1 and adapter 2 ● Radiator cap tester: YU-24460-01/90890-01325 Radiator cap tester adapter: YU-33984/90890-01352 NOTE: Apply water on the radiator cap seal. 3 Radiator cap 2.
  • Page 67 INSP CLUTCH ADJUSTMENT NOTE: Do not apply pressure more than specified ● pressure. Radiator should be filled fully. ● 4. Inspect: Pressure ● Impossible to maintain the specified pressure for 10 seconds → Repair. Radiator 1 ● Radiator hose joint 2 ●...
  • Page 68 THROTTLE CABLE ADJUSTMENT/ INSP THROTTLE LUBRICATION THROTTLE CABLE ADJUSTMENT 1. Check: Throttle grip free play a ● Out of specification → Adjust. Throttle grip free play a: 3 ~ 5 mm (0.12 ~ 0.20 in) 2. Adjust: Throttle grip free play ●...
  • Page 69 HOT STARTER LEVER ADJUSTMENT/ INSP AIR FILTER CLEANING HOT STARTER LEVER ADJUSTMENT 1. Check: Hot starter lever free play a ● Out of specification → Adjust. Hot starter lever free play a: 3 ~ 6 mm (0.12 ~ 0.24 in) 2.
  • Page 70 INSP AIR FILTER CLEANING 2. Clean: Air filter element ● Clean them with solvent. NOTE: After cleaning, remove the remaining solvent by squeezing the element. CAUTION: Do not twist the element when squeezing ● the element. Leaving too much of solvent in the ele- ●...
  • Page 71 INSP ENGINE OIL LEVEL INSPECTION 7. Install: Air filter element 1 ● Washer ● Fitting bolt ● 2 Nm (0.2 m · kg, 1.4 ft · lb) NOTE: Align the projection a on filter guide with the hole b in air filter case. ENGINE OIL LEVEL INSPECTION 1.
  • Page 72 INSP ENGINE OIL LEVEL INSPECTION (For USA and CDN) Recommended oil: At 5 ˚C (40 ˚F) or higher Å Yamalube 4 (20W-40) or SAE 20W-40 type SG motor oil (Non- Friction modified) At 15 ˚C (60 ˚F) or lower ı Yamalube 4 (10W-30) or SAE 10W-30 type SG motor oil (Non- Friction modified)
  • Page 73 INSP ENGINE OIL REPLACEMENT ENGINE OIL REPLACEMENT 1. Start the engine and warm it up for sev- eral minutes, and then turn off the engine and wait for five minute. 2. Place the machine on a level place and hold it on upright position by placing the suitable stand under the engine.

  • Page 74: Engine Oil Replacement

    INSP ENGINE OIL REPLACEMENT 7. If the oil filter is to be replaced during this oil change, remove the following parts and reinstall them. Replacement steps: Remove the oil filter element cover 1 and ● oil filter element 2. Check the O-rings 3, if cracked or dam- ●...
  • Page 75 OIL PRESSURE INSPECTION/ INSP PILOT SCREW ADJUSTMENT OIL PRESSURE INSPECTION 1. Check: Oil pressure ● Checking steps: Slightly loosen the oil pressure check bolt ● Start the engine and keep it idling until oil ● starts to seep from the oil pressure check bolt.
  • Page 76 ENGINE IDLING SPEED ADJUSTMENT/ INSP VALVE CLEARANCE INSPECTION AND ADJUSTMENT ENGINE IDLING SPEED ADJUSTMENT 1. Start the engine and thoroughly warm it 2. Attach: Inductive tachometer ● To spark plug lead. 3. Adjust: Engine idling speed ● Adjustment steps: Adjust the pilot screw. ●...
  • Page 77 INSP VALVE CLEARANCE INSPECTION AND ADJUSTMENT 3. Remove: Right radiator ● Refer to “RADIATOR” section in the CHAPTER 4. Carburetor ● Refer to “CARBURETOR” section in the CHAPTER 4. Spark plug ● Upper engine bracket ● Cylinder head cover ● Refer to “CAMSHAFTS”...
  • Page 78 INSP VALVE CLEARANCE INSPECTION AND ADJUSTMENT Checking steps: Turn the crankshaft counterclockwise with ● a wrench. Align the T.D.C. mark a on the rotor with ● the align mark b on the crankcase cover when piston is at T.D.C. on compression stroke.
  • Page 79 INSP VALVE CLEARANCE INSPECTION AND ADJUSTMENT Remove the valve lifters 1 and the pads ● NOTE: Place a rag in the timing chain space to ● prevent pads from falling into the crank- case. Identity each valve lifter and pad position ●...
  • Page 80 INSP VALVE CLEARANCE INSPECTION AND ADJUSTMENT Install the new pads 3 and the valve lift- ● ers 4. NOTE: Apply the engine oil on the valve lifters. ● Apply the molybdenum disulfide oil on the ● valve stem ends. Valve lifter must turn smoothly when ●...

  • Page 81: Valve Clearance Inspection And Adjustment

    INSP VALVE CLEARANCE INSPECTION AND ADJUSTMENT INTAKE MEASURED INSTALLED PAD NUMBER CLEARANCE 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240 0.00 ~ 0.04 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 0.05 ~ 0.09 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235...

  • Page 82: Chassis

    INSP CHASSIS/BRAKE SYSTEM AIR BLEEDING EC360000 CHASSIS EC361012 BRAKE SYSTEM AIR BLEEDING WARNING Bleed the brake system if: The system has been disassembled. ● A brake hose has been loosened or ● removed. The brake fluid is very low. ● The brake operation is faulty.
  • Page 83 INSP FRONT BRAKE ADJUSTMENT NOTE: If bleeding is difficult, it may be necessary to let the brake fluid system stabilize for a few hours. Repeat the bleeding procedure when the tiny bubbles in the system have disap- peared. j. Add brake fluid to the level line on the reservoir.

  • Page 84: Rear Brake Adjustment

    REAR BRAKE ADJUSTMENT/ INSP FRONT BRAKE PAD INSPECTION AND REPLACEMENT EC364002 REAR BRAKE ADJUSTMENT 1. Check: Brake pedal height a ● Out of specification → Adjust. Brake pedal height a: 5 mm (0.20 in) 2. Adjust: Brake pedal height ● Pedal height adjustment steps: Loosen the locknut 1.
  • Page 85 INSP FRONT BRAKE PAD INSPECTION AND REPLACEMENT Loosen the pad pin 2. ● Remove the brake hose holder 3 and ● brake caliper 4 from the front fork. Remove the pad pin and brake pads 5. ● Connect the transparent hose 6 to the ●...
  • Page 86 INSP REAR BRAKE PAD INSPECTION AND REPLACEMENT Install the pad pin plug B. ● Pad pin plug: 3 Nm (0.3 m • kg, 2.2 ft • lb) 3. Inspect: Brake fluid level ● Refer “BRAKE FLUID LEVEL INSPECTION” section. 4. Check: Brake lever operation ●...
  • Page 87 INSP REAR BRAKE PAD INSPECTION AND REPLACEMENT Remove the pad pin 6 and brake pads 7. ● Connect the transparent hose 8 to the ● bleed screw 9 and place the suitable con- tainer under its end. Loosen the bleed screw and push the ●...
  • Page 88 REAR BRAKE PAD INSULATOR INSPECTION/ INSP BRAKE FLUID LEVEL INSPECTION 3. Inspect: Brake fluid level ● Refer “BRAKE FLUID LEVEL INSPECTION” section. 4. Check: Brake pedal operation ● A softy or spongy feeling → Bleed brake system. Refer “BRAKE SYSTEM BLEEDING”...
  • Page 89 INSP SPROCKETS INSPECTION/DRIVE CHAIN INSPECTION SPROCKETS INSPECTION 1. Inspect: Sprocket teeth a ● Excessive wear → Replace. NOTE: Replace the drive sprocket, rear wheel sprocket and drive chain as a set. EC369002 DRIVE CHAIN INSPECTION 1. Remove: Master link clip ●...
  • Page 90 INSP DRIVE CHAIN SLACK ADJUSTMENT 5. Install: Drive chain 1 ● Joint 2 ● Master link clip 3 ● CAUTION: Be sure to install the master link clip to the direction as shown. a Turning direction 6. Lubricate: Drive chain ●...
  • Page 91 INSP FRONT FORK INSPECTION 3. Adjust: Drive chain slack ● Drive chain slack adjustment steps: Loosen the axle nut 1 and locknuts 2. ● Adjust the drive chain slack by turning the ● adjusters 3. To tighten → Turn the adjuster 3 coun- terclockwise.
  • Page 92 FRONT FORK OIL SEAL AND DUST SEAL CLEANING/ INSP FRONT FORK INTERNAL PRESSURE RELIEVING/ FRONT FORK REBOUND DAMPING FORCE ADJUSTMENT EC36D001 FRONT FORK OIL SEAL AND DUST SEAL CLEANING 1. Remove: Protector ● Dust seal 1 ● NOTE: Use a thin screw driver, and be careful not to damage the inner fork tube and dust seal.
  • Page 93 FRONT FORK COMPRESSION DAMPING FORCE INSP ADJUSTMENT Extent of adjustment Maximum Minimum 20 clicks out (from Fully turned in maximum posi- position tion) STANDARD POSITION: ● This is the position which is back by the spe- cific number of clicks from the fully turned-in position.

  • Page 94: Rear Shock Absorber Inspection

    INSP REAR SHOCK ABSORBER INSPECTION Extent of adjustment Maximum Minimum 20 clicks out Fully turned in (from maximum position position) STANDARD POSITION: ● This is the position which is back by the spe- cific number of clicks from the fully turned-in position.
  • Page 95 REAR SHOCK ABSORBER SPRING PRELOAD INSP ADJUSTMENT REAR SHOCK ABSORBER SPRING PRELOAD ADJUSTMENT 1. Elevate the rear wheel by placing the suitable stand under the engine. 2. Remove: Rear frame ● 3. Loosen: Locknut 1 ● 4. Adjust: Spring preload ●...

  • Page 96: Rear Shock Absorber Rebound Damping Force Adjustment

    REAR SHOCK ABSORBER REBOUND INSP DAMPING FORCE ADJUSTMENT EC36N014 REAR SHOCK ABSORBER REBOUND DAMPING FORCE ADJUSTMENT 1. Adjust: Rebound damping force ● By turning the adjuster 1. Stiffer a → Increase the rebound damp- ing force. (Turn the adjuster 1 in.) Softer b →...
  • Page 97 REAR SHOCK ABSORBER LOW COMPRESSION INSP DAMPING FORCE ADJUSTMENT EC36c000 REAR SHOCK ABSORBER LOW COMPRESSION DAMPING FORCE ADJUSTMENT 1. Adjust: Low compression damping force ● By turning the adjuster 1. Stiffer a → Increase the low compres- sion damping force. (Turn the adjuster 1 in.) Softer b →...
  • Page 98 REAR SHOCK ABSORBER HIGH COMPRESSION INSP DAMPING FORCE ADJUSTMENT EC36d000 REAR SHOCK ABSORBER HIGH COMPRESSION DAMPING FORCE ADJUSTMENT 1. Adjust: High compression damping force ● By turning the adjuster 1. Stiffer a → Increase the high compres- sion damping force. (Turn the adjuster 1 in.) Softer b →...
  • Page 99 TIRE PRESSURE CHECK/SPOKES INSPECTION AND INSP TIGHTENING/WHEEL INSPECTION EC36Q000 TIRE PRESSURE CHECK 1. Measure: Tire pressure ● Out of specification → Adjust. Standard tire pressure: 100 kPa (1.0 kgf/cm , 15 psi) NOTE: Check the tire while it is cold. ●...
  • Page 100 INSP STEERING HEAD INSPECTION AND ADJUSTMENT 2. Inspect: Bearing free play ● Exist play → Replace. EC36U013 STEERING HEAD INSPECTION AND ADJUSTMENT 1. Elevate the front wheel by placing a suit- able stand under the engine. 2. Check: Steering stem ●...
  • Page 101 INSP STEERING HEAD INSPECTION AND ADJUSTMENT Tighten the steering ring nut 3 using ● steering nut wrench 4. NOTE: Apply the lithium soap base grease on the ● thread of the steering stem. Set the torque wrench to the steering nut ●...
  • Page 102 INSP LUBRICATION Å Use Yamaha cable lube or equivalent on these LUBRICATION areas. To ensure smooth operation of all compo- ı Use SAE 10W-30 motor oil or suitable chain nents, lubricate your machine during setup, lubricants. after break-in, and after every race.

  • Page 103: Electrical

    INSP ELECTRICAL/SPARK PLUG INSPECTION EC370000 ELECTRICAL EC371001 SPARK PLUG INSPECTION 1. Remove: Spark plug ● 2. Inspect: Electrode 1 ● Wear/damage → Replace. Insulator color 2 ● Normal condition is a medium to light tan color. Distinctly different color → Check the engine condition.
  • Page 104 INSP IGNITION TIMING CHECK IGNITION TIMING CHECK 1. Remove: Timing mark accessing screw 1 ● 2. Attach: Timing light ● Inductive tachometer ● To the spark plug lead. Timing light: YM-33277-A/90890-03141 Inductive tachometer: YU-8036-B Engine tachometer: 90890-03113 3. Check: Ignition timing ●...

  • Page 105: Seat, Fuel Tank And Side Covers

    SEAT, FUEL TANK AND SIDE COVERS EC400000 ENGINE SEAT, FUEL TANK AND SIDE COVERS 1 Seat removal 2 Fuel tank removal Extent of removal: 3 Side covers removal 4 Number plate removal Extent of removal Order Part name Q’ty Remarks SEAT, FUEL TANK AND SIDE COVERS REMOVAL Preparation for removal...
  • Page 106 SEAT, FUEL TANK AND SIDE COVERS REMOVAL POINTS Side cover 1. Remove: Bolt (side cover) ● Left side cover 1 ● Right side cover 2 ● NOTE: Draw the side cover downward to remove it because its claws a are inserted in the air fil- ter case.

  • Page 107: Exhaust Pipe And Silencer

    EXHAUST PIPE AND SILENCER EC4S0000 EXHAUST PIPE AND SILENCER Å Except for USA 1 Silencer removal 2 Exhaust pipe removal Extent of removal: Extent of removal Order Part name Q’ty Remarks EXHAUST PIPE AND SILENCER REMOVAL Preparation for removal Right side cover Refer to “SEAT, FUEL TANK AND SIDE COVERS”...
  • Page 108 EXHAUST PIPE AND SILENCER INSPECTION Silencer and exhaust pipe 1. Inspect: Gasket 1 ● Damage → Replace. ASSEMBLY AND INSTALLATION Silencer and exhaust pipe 1. Install: Gasket ● Exhaust pipe 1 ● Nut (exhaust pipe) 2 ● 13 Nm (1.3 m · kg, 9.4 ft · lb) Bolt (exhaust pipe) 3 ●...

  • Page 109: Radiator

    RADIATOR EC450001 RADIATOR 1 Radiator removal Extent of removal: Extent of removal Order Part name Q’ty Remarks RADIATOR REMOVAL Preparation for removal Drain the coolant. Refer to “COOLANT REPLACEMENT” section in the CHAPTER 3. Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE COVERS”...
  • Page 110 RADIATOR EC456000 HANDLING NOTE WARNING Do not remove the radiator cap when the engine and radiator are hot. Scalding hot fluid and steam may be blown out under pressure, 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 111 RADIATOR 3. Install: Right radiator 1 ● Bolt (right radiator) 2 ● 10 Nm (1.0 m · kg, 7.2 ft · lb) Radiator hose 3 3 ● Refer to “CABLE ROUTING DIA- GRAM” section in the CHAPTER 2. 4. Install: Left radiator 1 ●...

  • Page 112: Carburetor

    CARBURETOR CARBURETOR 4 Nm (0.4 m kg, 2.9 ft • • 2 Nm (0.2 m kg, 1.4 ft • • 3 Nm (0.3 m kg, 2.2 ft • • 3 Nm (0.3 m kg, 2.2 ft • • 1 Carburetor removal Extent of removal: Extent of removal Order...
  • Page 113 CARBURETOR EC468000 CARBURETOR DISASSEMBLY 1 Carburetor disassembly Extent of removal: Extent of removal Order Part name Q’ty Remarks CARBURETOR DISASSEMBLY Carburetor breather hose Valve lever housing cover Screw (throttle shaft) Throttle valve Needle holder Jet needle Accelerator pump cover Spring Diaphragm (accelerator pump) Float chamber Leak jet...
  • Page 114 CARBURETOR Extent of removal Order Part name Q’ty Remarks Main jet Needle jet Spacer Pilot jet Starter jet Push rod Pull the push rod. Throttle shaft assembly Push rod link lever assembly Pilot air jet Cold starter plunger 4 - 10...
  • Page 115 CARBURETOR HANDLING NOTE CAUTION: Do not loosen the screws (throttle position sensor) 1 except when changing the throt- tle position sensor due to failure because it will cause a drop in engine performance. REMOVAL POINTS Pilot screw 1. Remove: Pilot screw 1 ●...
  • Page 116 CARBURETOR 2. Inspect: Main jet 1 ● Pilot jet 2 ● Needle jet 3 ● Starter jet 4 ● Pilot air jet 5 ● Leak jet 6 ● Damage → Replace. Contamination → Clean. NOTE: Use a petroleum based solvent for cleaning. ●...
  • Page 117 CARBURETOR Float height 1. Measure: Float height a ● Out of specification → Adjust. Float height: 8.0 mm (0.31 in) Measurement and adjustment steps: Hold the carburetor in an upside down ● position. NOTE: Slowly tilt the carburetor in the opposite ●...
  • Page 118 CARBURETOR Starter plunger 1. Inspect: Cold starter plunger 1 ● Hot starter plunger 2 ● Wear/damage → Replace. Accelerator pump 1. Inspect: Diaphragm (accelerator pump) 1 ● Spring (accelerator pump) 2 ● Accelerator pump cover 3 ● O-ring 4 ● Push rod 5 ●...
  • Page 119 CARBURETOR 3. Install: Spring 1 1 ● Lever 1 2 ● To lever 2 3. NOTE: Make sure the spring 1 fits on the stopper a of the lever 2. 4. Install: Spring 2 1 ● To lever 2 2. 5.
  • Page 120 CARBURETOR 1 2 3 8. Install: Throttle shaft assembly 1 ● Washer (metal) 2 ● Washer (resin) 3 ● Valve lever 4 ● NOTE: Apply the fluorochemical grease on the bear- ● ings. Fit the projection a on the throttle shaft ●...
  • Page 121 CARBURETOR 11. Install: Needle valve 1 ● Float 2 ● Float pin 3 ● NOTE: After installing the needle valve to the float, ● install them to the carburetor. Check the float for smooth movement. ● 12. Install: Pilot screw 1 ●...
  • Page 122 CARBURETOR 15. Install: Jet needle 1 ● Collar 2 ● Spring 3 ● Needle holder 4 ● Throttle valve plate 5 ● To throttle valve 6. 16. Install: Throttle valve assembly 1 ● Screw (throttle shaft) 2 ● NOTE: Install the valve lever rollers 3 into the slits a of the throttle valve.
  • Page 123 CARBURETOR Fully turn in the accelerator pump adjust- ● ing screw 3. Check that the link lever 4 has free play ● b by pushing lightly on it. Gradually turn out the adjusting screw ● while moving the link lever until it has no more free play.
  • Page 124 CARBURETOR 5. Install: Throttle cable 1 ● 6. Adjust: Throttle grip free play ● Refer to “THROTTLE CABLE ADJUST- MENT” section in the CHAPTER 3. 7. Install: Throttle cable cover 1 ● Screw (throttle cable cover) 2 ● 4 Nm (0.4 m · kg, 2.9 ft · lb) 8.

  • Page 125: Camshafts

    CAMSHAFTS CAMSHAFTS CYLINDER HEAD COVER 1 Cylinder head cover removal Extent of removal: Extent of removal Order Part name Q’ty Remarks CYLINDER HEAD COVER REMOVAL Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE COVERS” section. Carburetor Refer to “CARBURETOR”...
  • Page 126 CAMSHAFTS CAMSHAFTS 1 Camshaft removal Extent of removal: Extent of removal Order Part name Q’ty Remarks CAMSHAFTS REMOVAL Timing mark accessing screw Crankshaft end accessing screw Timing chain tensioner cap bolt Timing chain tensioner Refer to “REMOVAL POINTS”. Camshaft cap Clip Exhaust camshaft Intake camshaft...
  • Page 127 CAMSHAFTS REMOVAL POINTS Camshaft 1. Remove: Timing mark accessing screw 1 ● Crankshaft end accessing screw 2 ● 2. Align: T.D.C. mark ● With align mark. Checking steps: Turn the crankshaft counterclockwise with ● a wrench. Align the T.D.C. mark a on the rotor with ●...
  • Page 128 CAMSHAFTS 5. Remove: Exhaust camshaft 1 ● Intake camshaft 2 ● NOTE: Attach a wire 3 to the timing chain to prevent it from falling into the crankcase. INSPECTION Camshaft 1. Inspect: Cam lobe ● Pitting/scratches/blue discoloration → Replace. 2. Measure: Cam lobe length a and b ●...
  • Page 129 CAMSHAFTS 4. Measure: Camshaft-to-cap clearance ● Out of specification → Measure cam- shaft outside diameter. Camshaft-to-cap clearance: 0.020 ~ 0.054 mm (0.0008 ~ 0.0021 in) <Limit>: 0.08 mm (0.003 in) Measurement steps: Install the camshaft onto the cylinder ● head. 1 onto the ®...
  • Page 130 CAMSHAFTS Decompression system 1. Check: Decompression system ● Checking steps: Check that the decompression mecha- ● nism cam 1 moves smoothly. Check that the decompression mechanism ● cam lever pin 2 projects from the camshaft. Timing chain tensioner 1. Check: While pressing the tensioner rod lightly ●...
  • Page 131 CAMSHAFTS Fit the timing chain 3 onto both camshaft ● sprockets and install the camshafts on the cylinder head. NOTE: The camshafts should be installed onto the cylinder head so that the punch mark c on the exhaust camshaft and the punch mark d on the intake camshaft must align with the cylinder head surface, as shown in the illustration.
  • Page 132 CAMSHAFTS With the rod fully wound and the chain ● tensioner UP mark a facing upward, install the gasket 1 and the timing chain tensioner 2, and tighten the bolt 3 to the specified torque. Bolt (timing chain tensioner): 10 Nm (1.0 m • kg, 7.2 ft • lb) Release the screwdriver, check the ten- ●...
  • Page 133 10 Nm (1.0 m · kg, 7.2 ft · lb) NOTE: Apply the sealant on the cylinder head cover gasket. ® Quick gasket ACC-QUICK-GS-KT YAMAHA Bond No. 1215: 90890-85505 7. Install: Oil tank breather hose ● Cylinder head breather hose ●...

  • Page 134: Cylinder Head

    CYLINDER HEAD CYLINDER HEAD 1 Cylinder head removal Extent of removal: Extent of removal Order Part name Q’ty Remarks CYLINDER HEAD REMOVAL Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE COVERS” section. Exhaust pipe and silencer Refer to “EXHAUST PIPE AND SILENCER”...
  • Page 135 CYLINDER HEAD INSPECTION Cylinder head 1. Eliminate: Carbon deposits (from the combustion ● chambers) Use a rounded scraper. NOTE: Do not use a sharp instrument to avoid dam- aging or scratching: Spark plug threads ● Valve seats ● 2. Inspect: Cylinder head ●...
  • Page 136 CYLINDER HEAD ASSEMBLY AND INSTALLATION Cylinder head 1. Install: Dowel pin 1 ● Cylinder head gasket 2 ● Timing chain guide (exhaust side) 3 ● Cylinder head 4 ● NOTE: While pulling up the timing chain, install the timing chain guide (exhaust side) and cylinder head.

  • Page 137: Valves And Valve Springs

    VALVES AND VALVE SPRINGS VALVES AND VALVE SPRINGS 1 Valve removal Extent of removal: Extent of removal Order Part name Q’ty Remarks VALVES AND VALVE SPRINGS REMOVAL Preparation for removal Cylinder head Refer to “CYLINDER HEAD” section. Valve lifter Use special tool. Adjusting pad Refer to “REMOVAL POINTS”.
  • Page 138 VALVES AND VALVE SPRINGS REMOVAL POINTS Valve lifter and valve cotter 1. Remove: Valve lifter 1 ● Pad 2 ● NOTE: Identify each lifter 1 and pad 2 position very carefully so that they can be reinstalled in their original place. 2.
  • Page 139 VALVES AND VALVE SPRINGS INSPECTION Valve 1. Measure: Stem-to-guide clearance ● Stem-to-guide clearance = valve guide inside diameter a – valve stem diameter b Out of specification → Replace the valve guide. Clearance (stem to guide): Intake: 0.010 ~ 0.037 mm (0.0004 ~ 0.0015 in) <Limit>: 0.08 mm (0.003 in) Exhaust:...
  • Page 140 VALVES AND VALVE SPRINGS Valve guide remover: Intake: 4.0 mm (0.16 in) YM-4111/90890-04111 Exhaust: 4.5 mm (0.18 in) YM-4116/90890-04116 Valve guide installer: Intake: 4.0 mm (0.16 in) YM-4112/90890-04112 Exhaust: 4.5 mm (0.18 in) YM-4117/90890-04117 Valve guide reamer: Intake: 4.0 mm (0.16 in) YM-4113/90890-04113 Exhaust: 4.5 mm (0.18 in) YM-4118/90890-04118...
  • Page 141 VALVES AND VALVE SPRINGS 5. Measure: Runout (valve stem) ● Out of specification → Replace. Runout limit: 0.01 mm (0.0004 in) NOTE: When installing a new valve always replace ● the guide. If the valve is removed or replaced always ●...
  • Page 142 VALVES AND VALVE SPRINGS 9. Lap: Valve face ● Valve seat ● NOTE: After refacing the valve seat or replacing the valve and valve guide, the valve seat and valve face should be lapped. Lapping steps: Apply a coarse lapping compound to the ●...
  • Page 143 VALVES AND VALVE SPRINGS Valve spring 1. Measure: Valve spring free length a ● Out of specification → Replace. Free length (valve spring): Intake: 37.81 mm (1.49 in) <Limit>: 35.9 mm (1.41 in) Exhaust: 37.54 mm (1.48 in) <Limit>: 35.7 mm (1.41 in) 2.
  • Page 144 VALVES AND VALVE SPRINGS Combination of cylinder head and valve lifter 1. Combination: For this combination, match the paint color on the cylinder head with that on the valve lifter according to the chart below. Combination Valve lifter mark b Cylinder head mark a (color) (color)
  • Page 145 VALVES AND VALVE SPRINGS 3. Install: Valve cotter ● NOTE: While compressing the valve spring with a valve spring compressor 1 install the valve cotters. Valve spring compressor: YM-4019/90890-04019 4. To secure the valve cotters onto the valve stem, lightly tap the valve tip with a piece of wood.

  • Page 146: Cylinder And Piston

    CYLINDER AND PISTON CYLINDER AND PISTON 1 Cylinder removal 2 Piston removal Extent of removal: Extent of removal Order Part name Q’ty Remarks CYLINDER AND PISTON REMOVAL Preparation for removal Cylinder head Refer to “CYLINDER HEAD” section. Bolt (cylinder) Cylinder Piston pin clip Piston pin Use special tool.
  • Page 147 CYLINDER AND PISTON REMOVAL POINTS Piston and piston ring 1. Remove: Piston pin clip 1 ● Piston pin 2 ● Piston 3 ● NOTE: Put identification marks on each piston head ● for reference during reinstallation. Before removing each piston pin, deburr the ●...
  • Page 148 CYLINDER AND PISTON 77.00 ~ 77.01 mm Cylinder bore “C” (3.0315 ~ 3.0319 in) Taper limit “T” 0.05 mm (0.002 in) Out of round “R” 0.05 mm (0.002 in) “C” = Maximum D “T” = (Maximum D or D – (Maximum D or D “R”...
  • Page 149 CYLINDER AND PISTON Piston ring 1. Measure: Ring side clearance ● Use a feeler gauge 1. Out of specification → Replace the pis- ton and rings as a set. NOTE: Clean carbon from the piston ring grooves and rings before measuring the side clearance. Side clearance: Standard <Limit>...
  • Page 150 CYLINDER AND PISTON Piston pin 1. Inspect: Piston pin ● Blue discoloration/grooves → Replace, then inspect the lubrication system. 2. Measure: Piston pin-to-piston clearance ● Measurement steps: Measure the outside diameter (piston pin) ● If out of specification, replace the piston pin.
  • Page 151 CYLINDER AND PISTON 2. Position: Top ring ● 2nd ring ● Oil ring ● 45° Offset the piston ring end gaps as 135° 135° shown. a Top ring end b 2nd ring end c Oil ring end (upper) d Oil ring e Oil ring end (lower) 3.
  • Page 152 CYLINDER AND PISTON 3. Install: Cylinder gasket 1 ● Cylinder 2 ● NOTE: Install the cylinder with one hand while com- pressing the piston rings with the other hand. CAUTION: Pass the timing chain 3 through the tim- ● ing chain cavity. Be careful not to damage the timing chain ●...

  • Page 153: Clutch

    CLUTCH EC4A0000 CLUTCH 1 Push rod 1, 2 and push lever shaft removal 2 Push pod 1 disassembly Extent of removal: 3 Friction plate and clutch plate removal 4 Primary driven gear removal Extent of removal Order Part name Q’ty Remarks CLUTCH REMOVAL Preparation for removal...
  • Page 154 CLUTCH Extent of removal Order Part name Q’ty Remarks Friction plate Clutch plate Cushion spring Seat plate Nut (clutch boss) Use special tool. Look washer Refer to “REMOVAL POINTS”. Clutch boss Thrust washer Primary driven gear Push lever shaft 4 - 50...
  • Page 155 CLUTCH EC4A3000 REMOVAL POINTS Clutch boss 1. Remove: Nut 1 ● Lock washer 2 ● Clutch boss 3 ● NOTE: Straighten the lock washer tab and use the clutch holding tool 4 to hold the clutch boss. Å ı Clutch holding tool: YM-91042/90890-04086 Å...
  • Page 156 CLUTCH Friction plate 1. Measure: Friction plate thickness ● Out of specification → Replace friction plate as a set. Measure at all four points. Friction plate thickness: 2.9 ~ 3.1 mm (0.114 ~ 0.122 in) <Limit>: 2.7 mm (0.106 in) EC484600 Clutch plate 1.
  • Page 157 CLUTCH EC4A5000 ASSEMBLY AND INSTALLATION Push lever shaft 1. Install: Push lever shaft 1 ● Bolt (push lever shaft) 2 ● 10 Nm (1.0 m · kg, 7.2 ft · lb) NOTE: Apply the lithium soap base grease on the oil ●...
  • Page 158 CLUTCH 3. Bend the lock washer 1 tab. 4. Install: Seat plate 1 ● Cushion spring 2 ● NOTE: Install the seat plate with its chamfered por- ● tion a facing the clutch boss 3. Install the seat plate so that it is not caught ●...
  • Page 159 CLUTCH 7. Install: Push rod 2 1 ● Ball 2 ● Push rod 1 3 ● NOTE: Apply the engine oil on the push rod 1, 2 and ball. 8. Install: Pressure plate 1 ● 9. Install: Clutch spring 1 ●...

  • Page 160: Oil Filter Element, Water Pump And Right Crankcase Cover

    OIL FILTER ELEMENT, WATER PUMP AND RIGHT CRANKCASE COVER OIL FILTER ELEMENT, WATER PUMP AND RIGHT CRANKCASE COVER 1 Oil filter element removal 2 Water pump removal Extent of removal: 3 Right crankcase cover removal Extent of removal Order Part name Q’ty Remarks OIL FILTER ELEMENT, WATER...
  • Page 161 OIL FILTER ELEMENT, WATER PUMP AND RIGHT CRANKCASE COVER Extent of removal Order Part name Q’ty Remarks Water pump housing Oil delivery pipe Bolt (oil hose) Kickstarter crank Right crankcase cover Impeller Washer Impeller shaft Refer to “REMOVAL POINTS”. Oil seal Bearing 4 - 57...
  • Page 162 OIL FILTER ELEMENT, WATER PUMP AND RIGHT CRANKCASE COVER REMOVAL POINTS Impeller shaft 1. Remove: Impeller 1 ● Washer 2 ● Impeller shaft 3 ● NOTE: Hold the impeller shaft on its width across the flats a with spanners, etc. and remove the impeller.
  • Page 163 OIL FILTER ELEMENT, WATER PUMP AND RIGHT CRANKCASE COVER EC444200 Impeller shaft 1. Inspect: Impeller shaft 1 ● Bend/wear/damage → Replace. Fur deposits → Clean. EC444300 Impeller shaft gear 1. Inspect: Gear teeth a ● Wear/damage → Replace. EC4H4600 Bearing 1.
  • Page 164 OIL FILTER ELEMENT, WATER PUMP AND RIGHT CRANKCASE COVER 2. Install: Bearing 1 ● NOTE: Install the bearing by pressing its outer race parallel. Impeller shaft 1. Install: Impeller shaft 1 ● Washer 2 ● Impeller 3 ● 14 Nm (1.4 m · kg, 10 ft · lb) NOTE: Take care so that the oil seal lip is not dam- ●...
  • Page 165 OIL FILTER ELEMENT, WATER PUMP AND RIGHT CRANKCASE COVER 2. Install: Right crankcase cover 1 ● Bolt (right crankcase cover) 2 ● 10 Nm (1.0 m · kg, 7.2 ft · lb) NOTE: Apply the engine oil on the impeller shaft ●...
  • Page 166 OIL FILTER ELEMENT, WATER PUMP AND RIGHT CRANKCASE COVER Water pump housing 1. Install: Dowel pin 1 ● O-ring 2 ● NOTE: Apply the lithium soap base grease on the O- ring. 2. Install: Water pump housing 1 ● Bolt (water pump housing) 2 ●...

  • Page 167: Balancer

    BALANCER BALANCER 1 Balancer shaft drive gear 2 Balancer shaft Extent of removal: Extent of removal Order Part name Q’ty Remarks BALANCER REMOVAL Preparation for removal Primary driven gear Refer to “CLUTCH” section. Right crankcase cover Refer to “OIL FILTER ELEMENT, WATER PUMP AND RIGHT CRANK- CASE COVER”...
  • Page 168 BALANCER REMOVAL POINTS Balancer shaft drive gear and balancer shaft driven gear 1. Straighten the lock washer tab. 2. Loosen: Nut (primary drive gear) 1 ● Nut (balancer shaft driven gear) 2 ● NOTE: Place an aluminum plate a between the teeth of the balancer shaft drive gear 3 and driven gear 4.
  • Page 169 BALANCER ASSEMBLY AND INSTALLATION Balancer shaft, balancer shaft drive gear and balancer shaft driven gear 1. Install: Balancer shaft 1 ● NOTE: Apply the engine oil on the bearing. ● When installing the balancer shaft, align the ● center a of the balancer shaft weight along the line connecting the centers of the crank- shaft and balancer shaft.

  • Page 170: Oil Pump

    OIL PUMP OIL PUMP 1 Oil pump removal 2 Oil pump disassembly Extent of removal: Extent of removal Order Part name Q’ty Remarks OIL PUMP REMOVAL AND DIS- ASSEMBLY Preparation for removal Primary driven gear Refer to “CLUTCH” section. Right crankcase cover Refer to “OIL FILTER ELEMENT, WATER PUMP AND RIGHT CRANK- CASE COVER”...
  • Page 171 OIL PUMP Extent of removal Order Part name Q’ty Remarks Dowel pin Washer Oil pump drive shaft Rotor housing 4 - 67...
  • Page 172 OIL PUMP INSPECTION Oil pump 1. Inspect: Oil pump drive gear 1 ● Oil pump drive shaft 2 ● Rotor housing 3 ● Oil pump cover 4 ● Cracks/wear/damage → Replace. 2. Measure: Tip clearance a ● (between the inner rotor 1 and outer rotor 2) Side clearance b ●...
  • Page 173 OIL PUMP ASSEMBLY AND INSTALLATION Oil pump 1. Install: Oil pump drive shaft 1 ● Washer 2 ● Dowel pin 3 ● Inner rotor 1 4 ● NOTE: Apply the engine oil on the oil pump drive ● shaft and inner rotor 1. Fit the dowel pin into the groove in the inner ●...
  • Page 174 OIL PUMP 4. Install: Outer rotor 2 1 ● Dowel pin 2 ● Oil pump assembly 3 ● Bolt (oil pump assembly) ● [L = 25 mm (0.94 in)] 4 10 Nm (1.0 m · kg, 7.2 ft · lb) Bolt (oil pump assembly) ●...

  • Page 175: Kick Shaft And Shift Shaft

    KICK SHAFT AND SHIFT SHAFT KICK SHAFT AND SHIFT SHAFT 1 Kick shaft removal 2 Kick shaft disassembly Extent of removal: 3 Shift shaft removal 4 Segment removal Extent of removal Order Part name Q’ty Remarks KICK SHAFT AND SHIFT SHAFT REMOVAL Preparation for removal Oil pump...
  • Page 176 KICK SHAFT AND SHIFT SHAFT Extent of removal Order Part name Q’ty Remarks Torsion spring Roller Shift guide Refer to “REMOVAL POINTS”. Shift lever assembly Shift lever Pawl Pawl pin Spring Bolt (stopper lever) Stopper lever Torsion spring Segment Refer to “REMOVAL POINTS”. 4 - 72...
  • Page 177 KICK SHAFT AND SHIFT SHAFT REMOVAL POINTS Kick shaft assembly 1. Remove: Kick shaft assembly 1 ● NOTE: Unhook the torsion spring 2 from the hole a in the crankcase. EC4C3101 Shift guide and shift lever assembly 1. Remove: Bolt (shift guide) ●...
  • Page 178 KICK SHAFT AND SHIFT SHAFT EC4B4400 Shift shaft 1. Inspect: Shift shaft 1 ● Bend/damage → Replace. Spring 2 ● Broken → Replace. EC4C4100 Shift guide and shift lever assembly 1. Inspect: Shift guide 1 ● Shift lever 2 ● Pawl 3 ●...
  • Page 179 KICK SHAFT AND SHIFT SHAFT EC4B5111 Stopper lever 1. Install: Torsion spring 1 ● Stopper lever 2 ● Bolt (stopper lever) 3 ● 10 Nm (1.0 m · kg, 7.2 ft · lb) NOTE: Align the stopper lever roller with the slot on segment.
  • Page 180 KICK SHAFT AND SHIFT SHAFT Shift shaft 1. Install: Roller 1 ● Collar 2 ● Torsion spring 3 ● Shift shaft 4 ● NOTE: Apply the engine oil on the roller and shift shaft. 2. Install: Shift pedal 1 ● Bolt (shift pedal) 2 ●...
  • Page 181 KICK SHAFT AND SHIFT SHAFT 3. Install: Spring guide 1 ● NOTE: Slide the spring guide into the kick shaft, make sure the groove a in the spring guide fits on the stopper of the torsion spring. 4. Install: Kick shaft assembly 1 ●...

  • Page 182: Cdi Magneto

    CDI MAGNETO EC4L0000 CDI MAGNETO 1 CDI magneto removal Extent of removal: Extent of removal Order Part name Q’ty Remarks CDI MAGNETO REMOVAL Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE COVERS” section. Bolt (left radiator) Refer to “RADIATOR”...
  • Page 183 CDI MAGNETO EC4L3000 REMOVAL POINTS Rotor 1. Remove: Nut (rotor) 1 ● Washer 2 ● Use the rotor holding tool 3. Rotor holding tool: YU-1235/90890-01235 2. Remove: Rotor 1 ● Use the flywheel puller 2. Flywheel puller: YM-1189/90890-01189 NOTE: When installing the flywheel puller, turn it counterclockwise.
  • Page 184 Apply the sealant on the grommet of the CDI ● magneto lead. Tighten the screws using the T30 bit. ● ® Quick gasket ACC-QUICK-GS-KT YAMAHA Bond No. 1215: 90890-85505 2. Install: Woodruff key 1 ● Rotor 2 ● NOTE: Clean the tapered portions of the crankshaft ●...
  • Page 185 CDI MAGNETO 4. Connect: CDI magneto lead ● Refer to “CABLE ROUTING DIA- GRAM” section in the CHAPTER 2. 5. Install: Dowel pin ● Gasket (left crankcase cover) ● Left crankcase cover 1 ● Hose guide (cylinder head breather ● hose) 2 Bolt (left crankcase cover) 3 ●...

  • Page 186: Engine Removal

    ENGINE REMOVAL EC4M0000 ENGINE REMOVAL Extent of removal Order Part name Q’ty Remarks ENGINE REMOVAL Preparation for removal Hold the machine by placing the WARNING suitable stand under the frame. Support the machine securely so there is no danger of it falling over. Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE COVERS”...
  • Page 187 ENGINE REMOVAL 1 Engine removal Extent of removal: Extent of removal Order Part name Q’ty Remarks Ignition coil Disconnect the CDI magneto lead. Right engine guard Lower engine guard Neutral switch Bolt (oil hose) Drive chain sprocket cover Nut (drive sprocket) Lock washer Refer to “REMOVAL POINTS”.
  • Page 188 ENGINE REMOVAL EC4M3000 REMOVAL POINTS EC4F3100 Drive sprocket 1. Remove: Nut (drive sprocket) 1 ● Lock washer 2 ● NOTE: Straighten the lock washer tab. ● Loosen the nut while applying the rear brake. ● 2. Remove: Drive sprocket 1 ●...
  • Page 189 ENGINE REMOVAL EC4M5000 ASSEMBLY AND INSTALLATION Engine installation 1. Install: Engine 1 ● Install the engine from right side. Pivot shaft 2 ● 85 Nm (8.5 m · kg, 61 ft · lb) Engine mounting bolt (lower) 3 ● 69 Nm (6.9 m · kg, 50 ft · lb) Lower engine bracket 4 ●...
  • Page 190 ENGINE REMOVAL 2. Install: Lock washer 1 ● Nut (drive sprocket) 2 ● 75 Nm (7.5 m · kg, 54 ft · lb) NOTE: Tighten the nut while applying the rear brake. 3. Bend the lock washer tab to lock the nut. 4.

  • Page 191: Crankcase And Crankshaft

    CRANKCASE AND CRANKSHAFT CRANKCASE AND CRANKSHAFT 1 Crankcase separation 2 Crankshaft removal Extent of removal: Extent of removal Order Part name Q’ty Remarks CRANKCASE AND CRANK- SHAFT REMOVAL Preparation for removal Engine Refer to “ENGINE REMOVAL” section. Piston Refer to “CYLINDER AND PISTON” sec- tion.
  • Page 192 CRANKCASE AND CRANKSHAFT Extent of removal Order Part name Q’ty Remarks Bolt [L = 45 mm (1.77 in)] Bolt [L = 55 mm (2.17 in)] Bolt [L = 70 mm (2.76 in)] Hose guide Refer to “REMOVAL POINTS”. Clutch cable holder Right crankcase Left crankcase Oil strainer...
  • Page 193 CRANKCASE AND CRANKSHAFT CRANKCASE BEARING 1 Crankcase bearing removal Extent of removal: Extent of removal Order Part name Q’ty Remarks CRANKCASE BEARING REMOVAL Preparation for removal Transmission Refer to “TRANSMISSION, SHIFT Shift cam and shift fork CAM AND SHIFT FORK” section. Oil seal Bearing Refer to “REMOVAL POINTS”.
  • Page 194 CRANKCASE AND CRANKSHAFT REMOVAL POINTS Crankcase 1. Separate: Right crankcase ● Left crankcase ● Separation steps: Remove the crankcase bolts 1, hose ● guide 2 and clutch cable holder 3. NOTE: Loosen each bolt 1/4 of a turn at a time and after all the bolts are loosened, remove them.
  • Page 195 CRANKCASE AND CRANKSHAFT Crankshaft 1. Remove: Crankshaft 1 ● Use the crankcase separating tool 2. Crankcase separating tool: YU-1135-A/90890-01135 CAUTION: Do not use a hammer to drive out the crankshaft. Crankcase bearing 1. Remove: Bearing 1 ● NOTE: Remove the bearing from the crankcase by ●...
  • Page 196 CRANKCASE AND CRANKSHAFT EC4N4201 Crankshaft 1. Measure: Runout limit a ● Small end free play limit b ● Connecting rod big end side clearance ● Crank width d ● Out of specification → Replace. Use the dial gauge and a thickness gauge.
  • Page 197 CRANKCASE AND CRANKSHAFT EC4N5000 ASSEMBLY AND INSTALLATION Crankcase bearing 1. Install: Bearing ● Bearing stopper ● Bolt (bearing stopper) ● 10 Nm (1.0 m · kg, 7.2 ft · lb) Screw (bearing stopper) ● 10 Nm (1.0 m · kg, 7.2 ft · lb) Screw [bearing stopper (crankshaft)] 1 ●...
  • Page 198 10 Nm (1.0 m · kg, 7.2 ft · lb) 4. Apply: Sealant ● On the right crankcase 1. ® Quick gasket ACC-QUICK-GS-KT YAMAHA Bond No. 1215: 90890-85505 NOTE: Clean the contacting surface of left and right crankcase before applying the sealant. 5. Install: Dowel pin 1 ●...
  • Page 199 CRANKCASE AND CRANKSHAFT 6. Tighten: Hose guide 1 ● Clutch cable holder 2 ● Bolt (crankcase) 3 ● 12 Nm (1.2 m · kg, 8.7 ft · lb) NOTE: Tighten the crankcase tightening bolts in stage, using a crisscross pattern. 7.

  • Page 200: Transmission, Shift Cam And Shift Fork

    TRANSMISSION, SHIFT CAM AND SHIFT FORK EC4H0000 TRANSMISSION, SHIFT CAM AND SHIFT FORK 1 Shift fork, shift cam, main axle and drive axle removal Extent of removal: Extent of removal Order Part name Q’ty Remarks TRANSMISSION, SHIFT CAM AND SHIFT FORK REMOVAL Preparation for removal Engine Refer to “ENGINE REMOVAL”...
  • Page 201 TRANSMISSION, SHIFT CAM AND SHIFT FORK EC4H3000 REMOVAL POINTS EC4H3230 Transmission 1. Remove: Main axle 1 ● Drive axle 2 ● Shift cam ● Shift fork 3 ● Shift fork 2 ● Shift fork 1 ● NOTE: Remove assembly with the collar 3 installed ●...
  • Page 202 TRANSMISSION, SHIFT CAM AND SHIFT FORK EC4H4810 Shift fork, shift cam and segment 1. Inspect: Shift fork 1 ● Wear/damage/scratches → Replace. 2. Inspect: Shift cam 1 ● Segment 2 ● Wear/damage → Replace. 3. Check: Shift fork movement ● Unsmooth operation →...
  • Page 203 TRANSMISSION, SHIFT CAM AND SHIFT FORK 2. Install: 2nd wheel gear (28T) 1 ● 4th wheel gear (27T) 2 ● 3rd wheel gear (29T) 3 ● 5th wheel gear (25T) 4 ● 1st wheel gear (30T) 5 ● O-ring 6 ●...
  • Page 204 TRANSMISSION, SHIFT CAM AND SHIFT FORK 5. Install: Shift fork 1 (L) 1 ● Shift fork 2 (C) 2 ● Shift fork 3 (R) 3 ● Shift cam 4 ● To main axle and drive axle. NOTE: Apply the molybdenum disulfide oil on the ●...

  • Page 205: Chassis

    CHAS FRONT WHEEL AND REAR WHEEL EC500000 CHASSIS EC590000 FRONT WHEEL AND REAR WHEEL EC598000 FRONT WHEEL 1 Front wheel removal 2 Wheel bearing removal Extent of removal: 3 Brake disc removal Extent of removal Order Part name Q’ty Remarks FRONT WHEEL REMOVAL WARNING Hold the machine by placing the...
  • Page 206 CHAS FRONT WHEEL AND REAR WHEEL EC598100 REAR WHEEL 1 Rear wheel removal 2 Wheel bearing removal Extent of removal: 3 Brake disc removal Extent of removal Order Part name Q’ty Remarks REAR WHEEL REMOVAL WARNING Preparation for removal Hold the machine by placing the Support the machine securely so there is no danger of it falling over.
  • Page 207 CHAS FRONT WHEEL AND REAR WHEEL EC593000 REMOVAL POINTS EC523101 Rear wheel 1. Remove: Wheel 1 ● NOTE: Push the wheel forward and remove the drive chain 2. EC513201 Wheel bearing (if necessary) 1. Remove: Bearing 1 ● NOTE: Remove the bearing using a general bearing puller 2.
  • Page 208 CHAS FRONT WHEEL AND REAR WHEEL EC514200 Wheel axle 1. Measure: Wheel axle bends ● Out of specification → Replace. Use the dial gauge 1. Wheel axle bending limit: 0.5 mm (0.020 in) NOTE: The bending value is shown by one half of the dial gauge reading.
  • Page 209 CHAS FRONT WHEEL AND REAR WHEEL EC595000 ASSEMBLY AND INSTALLATION Front wheel 1. Install: Bearing (left) 1 ● Spacer 2 ● Bearing (right) 3 ● Oil seal 4 ● NOTE: Apply the lithium soap base grease on the ● bearing and oil seal lip when installing. Use a socket that matches the outside diam- ●...
  • Page 210 CHAS FRONT WHEEL AND REAR WHEEL 5. Install: Wheel axle 1 ● NOTE: Apply the lithium soap base grease on the wheel axle. 6. Install: Nut (wheel axle) 1 ● 105 Nm (10.5 m · kg, 75 ft · lb) 7.
  • Page 211 CHAS FRONT WHEEL AND REAR WHEEL 9. Install: Brake hose cover 1 ● Washer 2 ● Bolt [brake hose cover (M8)] 3 ● 16 Nm (1.6 m · kg, 11 ft · lb) Bolt [brake hose cover (M6)] 4 ● 7 Nm (0.7 m ·...
  • Page 212 CHAS FRONT WHEEL AND REAR WHEEL 3. Install: Rear wheel sprocket 1 ● Bolt (rear wheel sprocket) 2 ● Washer (rear wheel sprocket) 3 ● Nut (rear wheel sprocket) 4 ● 42 Nm (4.2 m · kg, 30 ft · lb) NOTE: Tighten the nuts in stage, using a crisscross pattern.
  • Page 213 CHAS FRONT WHEEL AND REAR WHEEL 8. Install: Right drive chain puller 1 ● Washer 2 ● Nut (wheel axle) 3 ● NOTE: Temporarily tighten the nut (wheel axle) at this point. 9. Adjust: Drive chain slack a ● Drive chain slack: 40 ~ 50 mm (1.6 ~ 2.0 in) Refer “DRIVE...

  • Page 214: Front Brake And Rear Brake

    CHAS FRONT BRAKE AND REAR BRAKE EC5A0000 FRONT BRAKE AND REAR BRAKE EC5A8000 FRONT BRAKE 1 Brake hose removal 2 Brake caliper removal Extent of removal: 3 Brake master cylinder removal Extent of removal Order Part name Q’ty Remarks FRONT BRAKE REMOVAL WARNING Preparation for removal Hold the machine by placing the...
  • Page 215 CHAS FRONT BRAKE AND REAR BRAKE EC5A8100 REAR BRAKE 1 Brake master cylinder removal 2 Brake hose removal Extent of removal: 3 Brake caliper removal Extent of removal Order Part name Q’ty Remarks REAR BRAKE REMOVAL WARNING Preparation for removal Hold the machine by placing the Support the machine securely so there is no suitable stand under the engine.
  • Page 216 CHAS FRONT BRAKE AND REAR BRAKE BRAKE CALIPER DISASSEMBLY Å Front ı Rear 1 Front brake caliper disassembly 2 Rear brake caliper disassembly Extent of removal: Extent of removal Order Part name Q’ty Remarks BRAKE CALIPER DISASSEM- Pad pin Brake pad Pad support Brake caliper piston Refer to “REMOVAL POINTS”.
  • Page 217 CHAS FRONT BRAKE AND REAR BRAKE BRAKE MASTER CYLINDER DISASSEMBLY Å Front ı Rear 1 Front brake master cylinder disassembly 2 Rear brake master cylinder disassembly Extent of removal: Extent of removal Order Part name Q’ty Remarks BRAKE MASTER CYLINDER DISASSEMBLY Brake master cylinder cap Diaphragm...
  • Page 218 CHAS FRONT BRAKE AND REAR BRAKE EC5A3000 Å REMOVAL POINTS Brake fluid 1. Remove: [Front] Brake master cylinder cap 1 ● [Rear] Brake master cylinder cap 1 ● Protector ● NOTE: Do not remove the diaphragm. ı Å Front ı Rear 2.
  • Page 219 CHAS FRONT BRAKE AND REAR BRAKE Brake caliper piston seal kit Å 1. Remove: Dust seal 1 ● Piston seal 2 ● NOTE: Remove the piston seals and dust seals by pushing them with a finger. CAUTION: ACHTUNG: Never attempt to pry out piston seals and ı...
  • Page 220 CHAS FRONT BRAKE AND REAR BRAKE Brake caliper Å ı 1. Inspect: Brake caliper cylinder inner surface a ● Wear/score marks → Replace brake caliper assembly. Å Front ı Rear 2. Inspect: Brake caliper piston 1 ● Wear/score marks → Replace brake caliper piston assembly.
  • Page 221 CHAS FRONT BRAKE AND REAR BRAKE 2. Install: Å Piston seal 1 ● Dust seal 2 ● WARNING Always use new piston seals and dust seals. NOTE: Fit the piston seals and dust seals onto the slot ı on brake caliper correctly. Å...
  • Page 222 CHAS FRONT BRAKE AND REAR BRAKE 2. Install: Copper washer 1 ● Union bolt 2 ● 30 Nm (3.0 m · kg, 22 ft · lb) WARNING Always use new copper washers. CAUTION: ACHTUNG: Install the brake hose so that its pipe por- tion a directs as shown and lightly touches the projection b on the brake cali- per.
  • Page 223 CHAS FRONT BRAKE AND REAR BRAKE 2. Install: Brake disc cover 1 ● Bolt (brake disc cover) 2 ● 7 Nm (0.7 m · kg, 5.1 ft · lb) 3. Install: Brake caliper 1 ● Rear wheel 2 ● Refer to “FRONT WHEEL AND REAR WHEEL”...
  • Page 224 CHAS FRONT BRAKE AND REAR BRAKE 3. Install: Å ı Spring 1 ● To brake master cylinder piston 2. NOTE: Install the spring at the smaller dia. side. Å Front ı Rear 4. Install: Å [Front] Brake master cylinder kit 1 ●...
  • Page 225 CHAS FRONT BRAKE AND REAR BRAKE 2. Install: Brake lever 1 ● Bolt (brake lever) 2 ● 6 Nm (0.6 m · kg, 4.3 ft · lb) Nut (brake lever) 3 ● 6 Nm (0.6 m · kg, 4.3 ft · lb) NOTE: Apply the lithium soap base grease on the brake lever sliding surface, bolt and contacting...
  • Page 226 CHAS FRONT BRAKE AND REAR BRAKE 4. Install: Pin 1 ● Washer 2 ● Cotter pin 3 ● NOTE: After installing, check the brake pedal height. Refer to “REAR BRAKE ADJUSTMENT” sec- tion in the CHAPTER 3. Front brake hose 1.
  • Page 227 CHAS FRONT BRAKE AND REAR BRAKE 4. Install: Copper washer 1 ● Brake hose 2 ● Union bolt 3 ● 30 Nm (3.0 m · kg, 22 ft · lb) WARNING Always use new copper washers. CAUTION: ACHTUNG: Install the brake hose so that its pipe por- tion a directs as shown and lightly touches the projection b on the brake master cylinder.
  • Page 228 CHAS FRONT BRAKE AND REAR BRAKE 2. Install: Brake hose holder 1 ● Screw (brake hose holder) 2 ● 1 Nm (0.1 m · kg, 0.7 ft · lb) CAUTION: ACHTUNG: After installing the brake hose holders, make sure the brake hose does not contact the spring (rear shock absorber).
  • Page 229 CHAS FRONT BRAKE AND REAR BRAKE 2. Air bleed: Brake system ● Refer “BRAKE SYSTEM BLEEDING” section in the CHAPTER 3. Inspect: Brake fluid level ● Fluid at lower level → Fill up. Refer “BRAKE FLUID LEVEL INSPECTION” section in the CHAP- TER 3.

  • Page 230: Front Fork

    CHAS FRONT FORK EC550000 FRONT FORK 1 Front fork removal Extent of removal: Extent of removal Order Part name Q’ty Remarks FRONT FORK REMOVAL WARNING Preparation for removal Hold the machine by placing the Support the machine securely so there is no suitable stand under the engine.
  • Page 231 CHAS FRONT FORK EC558000 FRONT FORK DISASSEMBLY 1 Oil seal removal 2 Damper rod removal Extent of removal: Extent of removal Order Part name Q’ty Remarks FRONT FORK DISASSEMBLY Front fork cap bolt Refer to “REMOVAL POINTS”. Fork spring Drain the fork oil. Dust seal Stopper ring Refer to “REMOVAL POINTS”.
  • Page 232 CHAS FRONT FORK EC556000 HANDLING NOTE NOTE: The front fork requires careful attention. So it is recommended that the front fork be main- tained at the dealers. CAUTION: ACHTUNG: To prevent an accidental explosion of air, following instructions should observed: The front fork with a built-in piston rod ●...
  • Page 233 CHAS FRONT FORK EC553201 Inner tube 1. Remove: Dust seal 1 ● Stopper ring 2 ● Using slotted-head screwdriver. CAUTION: ACHTUNG: Take care not to scratch the inner tube. 2. Remove: Inner tube 1 ● Oil seal removal steps: Push in slowly a the inner tube just before ●...
  • Page 234 CHAS FRONT FORK EC554200 Base valve 1. Inspect: Valve assembly 1 ● Wear/damage → Replace. O-ring 2 ● Damage → Replace. EC554400 Fork spring 1. Measure: Fork spring free length a ● Out of specification → Replace. Fork spring free length: 460 mm (18.1 in) <Limit>: 455 mm (17.9 in) EC554502...
  • Page 235 CHAS FRONT FORK Front fork cap bolt 1. Inspect: Front fork cap bolt 1 ● O-ring 2 ● Air bleed screw 3 ● Wear/damage → Replace. EC555000 ASSEMBLY AND INSTALLATION Front fork assembly 1. Wash the all parts in a clean solvent. 2.
  • Page 236 CHAS FRONT FORK 5. Install: Spring guide 1 ● Locknut 2 ● To damper rod 3. NOTE: Install the spring guide with its cut a facing ● upward. With its thread b facing upward, fully finger ● tighten the locknut onto the damper rod. 6.
  • Page 237 CHAS FRONT FORK 9. Install: Slide metal 1 ● Oil seal washer 2 ● To outer tube slot. NOTE: Press the slide metal into the outer tube with fork seal driver 3. Fork seal driver: YM-01442/90890-01442 10. Install: Oil seal 1 ●...
  • Page 238 CHAS FRONT FORK 13. Check: Inner tube smooth movement ● Tightness/binding/rough spots → Repeat the steps 2 to 12. 14. Compress the front fork fully. 15. Fill: Front fork oil ● Until outer tube top surface with recom- mended fork oil 1. Recommended oil: Suspension oil “01”...
  • Page 239 CHAS FRONT FORK 19. Wait ten minutes until the air bubbles have been removed from the front fork, and the oil has dispense evenly in system before setting recommended oil level. NOTE: Fill with the fork oil up to the top end of the outer tube, or the fork oil will not spread over to every part of the front forks, thus making it impossible to obtain the correct level.
  • Page 240 CHAS FRONT FORK 21. Measure: Distance a ● Out of specification → Turn into the locknut. Distance a: 20 mm (0.79 in) or more Between damper rod 1 top and locknut 2 top. 22. Loosen: Rebound damping adjuster 1 ● NOTE: Loosen the rebound damping adjuster finger ●...
  • Page 241 CHAS FRONT FORK 26. Tighten: Front fork cap bolt (locknut) 1 ● 29 Nm (2.9 m · kg, 21 ft · lb) NOTE: While compressing the fork spring, set the ● thin type spanners 2 between the spacer 3 and spring guide 4. Hold the locknut 5 and tighten the front fork ●...
  • Page 242 CHAS FRONT FORK 4. Tighten: Pinch bolt (upper bracket) 1 ● 23 Nm (2.3 m · kg, 17 ft · lb) Pinch bolt (lower bracket) 2 ● 20 Nm (2.0 m · kg, 14 ft · lb) CAUTION: ACHTUNG: Tighten the lower bracket to specified torque.

  • Page 243: Handlebar

    CHAS HANDLEBAR EC5B0000 HANDLEBAR 1 Handlebar removal Extent of removal: Extent of removal Order Part name Q’ty Remarks HANDLEBAR REMOVAL Preparation for removal Number plate Remove the clamp portion only. Hot starter cable Disconnect at the lever side. Hot starter lever holder Clutch cable Disconnect at the lever side.
  • Page 244 CHAS HANDLEBAR EC5B3000 REMOVAL POINTS Brake master cylinder 1. Remove: Brake master cylinder bracket 1 ● Brake master cylinder 2 ● CAUTION: ACHTUNG: Do not let the brake master cylinder hang ● on the brake hose. Keep the brake master cylinder cap side ●...
  • Page 245 CHAS HANDLEBAR EC5B5000 ASSEMBLY AND INSTALLATION Handlebar 1. Install: Handlebar 1 ● Handlebar upper holder 2 ● Bolt (handlebar upper holder) 3 ● 28 Nm (2.8 m · kg, 20 ft · lb) NOTE: The handlebar upper holder should be ●...
  • Page 246 CHAS HANDLEBAR 4. Install: Collar 1 ● Grip cap cover 2 ● Throttle grip 3 ● NOTE: Apply the lithium soap base grease on the throttle grip sliding surface. 5. Install: Throttle cables 1 ● To tube guide 2. NOTE: Apply the lithium soap base grease on the throttle cable end and tube guide cable wind- ing portion.
  • Page 247 CHAS HANDLEBAR 8. Install: Brake master cylinder 1 ● Brake master cylinder bracket 2 ● Bolt (brake master cylinder bracket) 3 ● 9 Nm (0.9 m · kg, 6.5 ft · lb) NOTE: Install the bracket so that the arrow mark a ●...
  • Page 248 CHAS HANDLEBAR 12. Clamp the clamp portion a of the num- ber plate to the handlebar. 13. Insert the end of the fuel tank breather hose 1 into the hole of the number plate. 5 - 44...

  • Page 249: Steering

    CHAS STEERING EC560000 STEERING 1 Lower bracket removal 2 Bearing removal Extent of removal: Extent of removal Order Part name Q’ty Remarks STEERING REMOVAL WARNING Preparation for removal Hold the machine by placing the Support the machine securely so there is no suitable stand under the engine.
  • Page 250 CHAS STEERING EC563000 REMOVAL POINTS Steering ring nut 1. Remove: Steering ring nut 1 ● Use the steering nut wrench 2. Steering nut wrench: YU-33975/90890-01403 WARNING Support the steering stem so that it may not fall down. Lower bearing 1. Remove: Lower bearing 1 ●...
  • Page 251 CHAS STEERING EC564101 Bearing and ball race 1. Wash the bearings and ball races with a solvent. 2. Inspect: Bearing 1 ● Ball race ● Pitting/damage → Replace bearings and ball races as a set. Install the bearing in the ball races. Spin the bearings by hand.
  • Page 252 CHAS STEERING 4. Install: Steering ring nut 1 ● 7 Nm (0.7 m · kg, 5.1 ft · lb) Tighten the steering ring nut using the steering nut wrench 2. Refer to “STEERING HEAD INSPEC- TION AND ADJUSTMENT” section in the CHAPTER 3.
  • Page 253 CHAS STEERING 10. Tighten: Pinch bolt (upper bracket) 1 ● 23 Nm (2.3 m · kg, 17 ft · lb) Pinch bolt (lower bracket) 2 ● 20 Nm (2.0 m · kg, 14 ft · lb) CAUTION: ACHTUNG: Tighten the lower bracket to specified torque.

  • Page 254: Swingarm

    CHAS SWINGARM EC570000 SWINGARM 1 Swingarm removal Extent of removal: Extent of removal Order Part name Q’ty Remarks SWINGARM REMOVAL WARNING Preparation for removal Hold the machine by placing the Support the machine securely so there is no suitable stand under the engine. danger of it falling over.
  • Page 255 CHAS SWINGARM EC578000 SWINGARM DISASSEMBLY 1 Swingarm disassembly 2 Connecting rod removal and disassembly Extent of removal: 3 Relay arm removal and disassembly Extent of removal Order Part name Q’ty Remarks SWINGARM DISASSEMBLY Relay arm Connecting rod Collar Oil seal Thrust bearing Bushing Oil seal...
  • Page 256 CHAS SWINGARM EC573000 REMOVAL POINTS EC573200 Bearing 1. Remove: Bearing 1 ● NOTE: Remove the bearing by pressing its outer race. INSPECTION Wash the bearings, bushings, collars, and cov- ers in a solvent. Swingarm 1. Inspect: Bearing 1 ● Bushing 2 ●...
  • Page 257 CHAS SWINGARM EC574310 Connecting rod 1. Inspect: Bearing (polylube bearing) 1 ● Collar 2 ● Free play exists/unsmooth revolution/rust → Replace bearing and collar as a set. 2. Inspect: Bearing (polylube bearing) 1 ● Loss of solid lubrication → Replace. Oil seal 3 ●...
  • Page 258 CHAS SWINGARM 2. Install: Bearing 1 ● Oil seal 2 ● To relay arm. NOTE: 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. Installed depth of bearings a: 5 mm (0.20 in) 3.
  • Page 259 CHAS SWINGARM 3. Install: Collar 1 ● To connecting rod 2. NOTE: Apply the molybdenum disulfide grease on the collar and oil seal lips. 4. Install: Connecting rod 1 ● Bolt (connecting rod) 2 ● Washer 3 ● Nut (connecting rod) 4 ●...
  • Page 260 CHAS SWINGARM 8. Install: Bolt (connecting rod) 1 ● Washer 2 ● Nut (connecting rod) 3 ● NOTE: Apply the molybdenum disulfide grease on ● the bolt. Do not tighten the nut yet. ● 9. Install: Bolt (rear shock absorber-relay arm) 1 ●...
  • Page 261 CHAS SWINGARM 13. Install: Bolt (lower chain tensioner) 1 ● Washer 2 ● Collar 3 ● Lower chain tensioner 4 ● Nut (lower chain tensioner) 5 ● 20 Nm (2.0 m · kg, 14 ft · lb) 14. Install: Drive chain support 1 ●...

  • Page 262: Rear Shock Absorber

    CHAS REAR SHOCK ABSORBER EC580000 REAR SHOCK ABSORBER 1 Rear shock absorber removal 2 Rear shock absorber disassembly Extent of removal: Extent of removal Order Part name Q’ty Remarks REAR SHOCK ABSORBER WARNING REMOVAL Support the machine securely so there is no Preparation for removal Hold the machine by placing the danger of it falling over.
  • Page 263 CHAS REAR SHOCK ABSORBER Extent of removal Order Part name Q’ty Remarks Upper spring guide Spring (rear shock absorber) Bearing Refer to “REMOVAL POINTS”. 5 - 59...
  • Page 264 1. Wear eye protection to prevent eye damage from escaping gas and/or metal chips. WARNING To dispose of a damaged or worn-out rear shock absorber, take the unit to your Yamaha dealer for this disposal procedure. 5 - 60...
  • Page 265 CHAS REAR SHOCK ABSORBER EC583000 REMOVAL POINTS EC583320 Bearing 1. Remove: Stopper ring (upper bearing) 1 ● NOTE: Press in the bearing while pressing its outer race and remove the stopper ring. 2. Remove: Upper bearing 1 ● NOTE: Remove the bearing by pressing its outer race. 3.
  • Page 266 CHAS REAR SHOCK ABSORBER EC585000 ASSEMBLY AND INSTALLATION EC585300 Bearing 1. Install: Upper bearing 1 ● NOTE: Install the bearing parallel until the stopper ring groove appears by pressing its outer race. CAUTION: ACHTUNG: Do not apply the grease on the bearing outer race because it will wear the rear shock absorber surface on which the bear- ing is press fitted.
  • Page 267 CHAS REAR SHOCK ABSORBER 2. Tighten: Adjuster 1 ● 3. Adjust: Spring length (installed) a ● Spring length (installed) a: Standard Extent of length adjustment 248 mm (9.76 in) 240.5 ~ 258.5 mm (9.47 ~ 10.18 in) *260 mm (10.24 in) *255.5 ~ 273.5 mm (10.06 ~ 10.77 in) * For EUROPE...
  • Page 268 CHAS REAR SHOCK ABSORBER 2. Install: Bushing 1 ● Collar 2 ● Dust seal 3 ● NOTE: Apply the molybdenum disulfide grease on ● the bearing. Apply the lithium soap base grease on the ● bushing, collars and dust seals. Install the dust seals with their lips facing ●...

  • Page 269: Electrical Components And Wiring Diagram

    – ELEC ELECTRICAL COMPONENTS AND WIRING DIAGRAM EC600000 ELECTRICAL EC610000 ELECTRICAL COMPONENTS AND WIRING DIAGRAM EC611000 ELECTRICAL COMPONENTS 1 Engine stop switch COLOR CODE 2 Throttle position sensor W .....White B...... Black Y ......Yellow 3 Neutral switch Br ....Brown B/L ....Black/Blue G .....

  • Page 270: Map-Controlled Cdi Unit

    – ELEC MAP-CONTROLLED CDI UNIT MAP-CONTROLLED CDI UNIT A map-controlled, CDI ignition system is used in the YZ250F. The microcomputer in the CDI unit detects the engine speed and throttle position, thus determining the optimum ignition timing through the entire operating range. In this way, quick throttle response can be achieved according to various riding conditions.

  • Page 271: Ignition System

    – ELEC IGNITION SYSTEM EC620000 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 *Clean or replace Spark gap test spark plug.
  • Page 272 – ELEC IGNITION SYSTEM SPARK GAP TEST Å 1. Disconnect the spark plug cap from spark plug. 2. Remove the ignition coil cap. 3. Connect the dynamic spark tester 1 (ignition checker 2) as shown. Ignition coil 3 ● Spark plug 4 ●...
  • Page 273 – ELEC IGNITION SYSTEM EC626002 IGNITION COIL INSPECTION 1. Inspect: Primary coil resistance ● Out of specification → Replace. Tester (+) lead → Orange lead 1 Tester (–) lead → Black lead 2 Primary coil Tester selector resistance position 0.08 ~ 0.10 Ω at Ω...
  • Page 274 – ELEC IGNITION SYSTEM 2. Inspect: Charging coil 1 resistance ● Out of specification → Replace. Tester (+) lead → Brown lead 1 Tester (–) lead → Green lead 2 Charging coil 1 Tester selector resistance position 720 ~ 1,080 Ω Ω...

  • Page 275: Throttle Position Sensor System

    – ELEC THROTTLE POSITION SENSOR SYSTEM THROTTLE POSITION SENSOR SYSTEM INSPECTION STEPS If the throttle position sensor will not operate, use the following inspection steps. No good Check entire ignition Repair or replace. system for connection. No good Check throttle position Throttle posi- Replace.
  • Page 276 – ELEC THROTTLE POSITION SENSOR SYSTEM HANDLING NOTE CAUTION: Do not loosen the screws (throttle position sensor) 1 except when changing the throt- tle position sensor due to failure because it will cause a drop in engine performance. EC624000 COUPLERS AND LEADS CONNECTION INSPECTION 1.
  • Page 277 – ELEC THROTTLE POSITION SENSOR SYSTEM 3. Inspect: Throttle position sensor coil variable ● resistance Check that the resistance in increased as the throttle grip is moved from the full close position to the full open posi- tion. Out of specification → Replace. Tester (+) lead →...
  • Page 278 – ELEC THROTTLE POSITION SENSOR SYSTEM 4. Install: Throttle position sensor coupler ● 5. Adjust: Engine idling speed ● Refer to “ENGINE IDLING SPEED ADJUSTMENT” section in the CHAP- TER 3. 6. Insert the thin electric conductors 2 (lead) into the throttle position sensor coupler 1, as shown, and connect the tester to them.
  • Page 279 – ELEC THROTTLE POSITION SENSOR SYSTEM 9. Tighten: Screw (throttle position sensor) 1 ● NOTE: Tighten the screws (throttle position sensor) using the T25 bit. 10. Stop the engine. THROTTLE POSITION SENSOR INPUT VOLTAGE INSPECTION 1. Disconnect the throttle position sensor coupler.

  • Page 280: Tuning

    T U N SETTING EC700000 TUNING EC710000 ENGINE Carburetor setting The air/fuel mixture will vary depending on ● atmospheric conditions. Therefore, it is nec- essary to take into consideration the air pres- sure, ambient temperature, humidity, etc., when adjusting the carburetor. Perform a test run to check for proper engine ●...
  • Page 281 T U N SETTING CAUTION: The carburetor is extremely sensitive to ● foreign matter (dirt, sand, water, etc.). During installation, do not allow foreign matter to get into the carburetor. Always handle the carburetor and its ● components carefully. Even slight scratches, bends or damage to carbure- tor parts may prevent the carburetor from...
  • Page 282 T U N SETTING Effects of the setting parts on the throttle valve opening Å ı Å Closed ı Fully open 1 Pilot screw/pilot jet 2 Throttle valve cutaway 3 Jet needle 4 Main jet Main system The FLATCR carburetor has a primary main jet.
  • Page 283 T U N SETTING 1 Jet needle 2 Pilot air jet 3 Needle jet 4 Main jet 5 Pilot jet 6 Pilot screw Main jet adjustment The richness of the air-fuel mixture at full throt- tle can be set by changing the main jet 1. Standard main jet #178 If the air-fuel mixture is too rich or too lean, the...
  • Page 284 T U N SETTING Pilot screw adjustment The richness of the air-fuel mixture with the throttle fully closed to 1/4 open can be set by turning the pilot screw 1. Turning in the pilot screw will make the mixture lean at low speeds, and turning it out will enrich it.
  • Page 285 T U N SETTING Effects of adjusting the pilot jet (reference) Å ı –5% Å Idle ı Fully open Jet needle groove position adjustment Adjusting the jet needle 1 position affects the acceleration when the throttle is 1/8 to 3/4 open.
  • Page 286 T U N SETTING Jet needle adjustment The jet needle is adjusted by changing it. OBELP Standard jet needle *OBEKP * For EUROPE The tapered sections of all jet needles have the same starting positions, but the needles are available with different straight-portion diameters.
  • Page 287 T U N SETTING Leak jet adjustment (accelerator pump adjustment) The leak jet 1 is a setting part that adjusts the flow of fuel discharged by the accelerator pump. Since the accelerator pump operates only when throttle is open, the leak jet is used to adjust a fuel mixture ratio for quick throttle opening and is therefore different from other setting parts that adjust a fuel mixture for each...
  • Page 288 T U N SETTING EC71Q000 Carburetor setting parts Part name Size Part number Main jet Rich #190 4MX-14943-45 #188 4MX-14943-95 #185 4MX-14943-44 #182 4MX-14943-94 #180 4MX-14943-43 (STD) #178 4MX-14943-93 #175 4MX-14943-42 #172 4MX-14943-92 #170 4MX-14943-41 #168 4MX-14943-91 Lean #165 4MX-14943-40 Pilot jet Rich 4MX-14948-07...
  • Page 289 T U N SETTING Examples of carburetor setting depending on symptom Symptom Setting Checking Discoloration of spark plug → At full throttle Increase main jet calibration no. Hard breathing (Gradually) If tan color, it is in good condition. Shearing noise If cannot be corrected: Whitish spark plug Clogged float valve seat...

  • Page 290: Chassis

    T U N SETTING EC720000 CHASSIS Selection of the secondary reduction ratio (Sprocket) Secondary Number of rear wheel sprocket teeth reduction = Number of drive sprocket teeth ratio Standard secondary 48/13 (3.692) reduction ratio <Requirement for selection of secondary gear reduction ratio>...
  • Page 291 T U N SETTING EC72N000 Drive and driven sprockets setting parts Part name Size Part number Drive sprocket 1 (STD) 9383B-13218 Rear wheel 5ET-25447-00 sprocket 2 (STD) 5NY-25448-00 5NY-25449-00 5NY-25450-00 5NY-25451-00 5NY-25452-00 EC721002 Tire pressure Tire pressure should be adjust to suit the road surface condition of the circuit.
  • Page 292 T U N SETTING EC722011 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. The front fork setting includes the following three factors: 1. Setting of air spring characteristics Change the fork oil level.
  • Page 293 T U N SETTING EC727020 Spring preload adjustment The spring preload is adjusted by installing the adjustment washer 1 between the fork spring 2 and damper rod 3. CAUTION: Do not install three or more adjustment washers for each front fork. WARNING Always adjust each front fork to the same setting.
  • Page 294 T U N SETTING 2. Use of stiff spring Generally a stiff spring gives a stiff riding feeling. Rebound damping tends to become weaker, resulting in lack of a sense of contact with the road surface or in a vibrating handlebar. To set a stiff spring: Change the rebound damping.
  • Page 295 T U N SETTING EC72P000 Front fork setting parts Adjustment washer 1 ● TYPE (thickness) PART NUMBER T = 2.3 mm (0.09 in) 4SS-23364-L0 Front fork spring 2 ● [Equal pitch spring] I.D. SPRING SPRING TYPE MARK RATE PART NUMBER (slits) 0.380 4SS-23141-10...
  • Page 296 T U N SETTING EC72B000 Rear suspension setting The rear suspension setting should be made depending on the rider’s feeling of an actual run and the circuit conditions. The rear suspension setting includes the fol- lowing two factors: 1. Setting of spring preload Change the set length of the spring.
  • Page 297 T U N SETTING NOTE: If the machine is new and after it is broken in, ● the same set length of the spring may change because of the initial fatigue, etc. of the spring. Therefore, be sure to make re- evaluation.
  • Page 298 T U N SETTING CAUTION: When using a rear shock absorber other than currently installed, use the one whose overall length a does not exceed the stan- dard as it may result in faulty performance. Never use one whose overall length is greater than standard.
  • Page 299 T U N SETTING EC72Q000 Rear shock absorber setting parts Rear shock spring 1 ● [Equal pitch spring] I.D. SPRING SPRING SPRING TYPE COLOR/ FREE RATE PART NUMBER POINT LENGTH 5UN-22212-00 Brown/1 SOFT 5UN-22212-10 Green/1 5UN-22212-20 Red/1 5UN-22212-30 Black/1 5UN-22212-40 Blue/1 STIFF 5UN-22212-50...

  • Page 300: Suspension Setting

    T U N SETTING EC72H002 Suspension setting Front fork ● NOTE: If any of the following symptoms is experienced with the standard position as the base, make ● resetting 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 ~ ●...
  • Page 301 T U N SETTING Rear shock absorber ● NOTE: If any of the following symptoms is experienced with the standard position as the base, make ● resetting by reference to the adjustment procedure given in the same chart. Adjust the rebound damping in 2-click increments or decrements. ●...
  • Page 304 YAMAHA MOTOR CO., LTD. PRINTED ON RECYCLED PAPER PRINTED IN JAPAN 2002.07-3.4×1 CR 2500 SHINGAI IWATA SHIZUOKA JAPAN...

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