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Kawasaki KX250F Service Manual

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Table of Contents
KX250F
Motorcycle
Service Manual

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Table of Contents
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  Summary of Contents for Kawasaki KX250F

  • Page 1 KX250F Motorcycle Service Manual...
  • Page 3 Quick Reference Guide General Information Periodic Maintenance Fuel System (DFI) Cooling System Engine Top End Clutch Engine Lubrication System Engine Removal/Installation Crankshaft/Transmission Wheels/Tires 10 j Final Drive 11 j Brakes 12 j Suspension 13 j Steering 14 j Frame 15 j Electrical System 16 j Appendix...
  • Page 5 All rights reserved. No parts of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic mechanical photocopying, recording or otherwise, without the prior written permission of Quality Assurance Division/Motorcycle & Engine Company/Kawasaki Heavy Industries, Ltd., Japan.
  • Page 6 LIST OF ABBREVIATIONS ampere(s) pound(s) ABDC after bottom dead center meter(s) alternating current minute(s) ATDC after top dead center newton(s) BBDC before bottom dead center pascal(s) bottom dead center horsepower BTDC before top dead center pound(s) per square inch °C degree(s) Celsius revolution direct current...
  • Page 7: How To Use This Manual

    NOTE maintenance. • ○ This note symbol indicates points of par- Use proper tools and genuine Kawasaki Mo- ticular interest for more efficient and con- torcycle parts. Special tools, gauges, and venient operation. testers that are necessary when servicing Kawasaki motorcycles are introduced by the •...
  • Page 9: Table Of Contents

    GENERAL INFORMATION 1-1 General Information Table of Contents Before Servicing ........................Model Identification......................... General Specifications......................Technical Information - Dual Injector ..................1-11 Unit Conversion Table ......................1-13...
  • Page 10: Before Servicing

    1-2 GENERAL INFORMATION Before Servicing Before starting to perform an inspection service or carry out a disassembly and reassembly opera- tion on a motorcycle, read the precautions given below. To facilitate actual operations, notes, illustra- tions, photographs, cautions, and detailed descriptions have been included in each chapter wherever necessary.
  • Page 11: Replacement Parts

    Replacement Parts Replacement parts must be KAWASAKI genuine or recommended by KAWASAKI. Gaskets, O-rings, oil seals, grease seals, circlips, cotter pins or self-locking nuts must be replaced with new ones whenever disassembled.
  • Page 12: General Information

    1-4 GENERAL INFORMATION Before Servicing Tightening Torque Incorrect torque applied to a bolt, nut, or screw may lead to serious damage. Tighten fasteners to the specified torque using a good quality torque wrench. Often, the tightening sequence is followed twice-initial tightening and final tightening with torque wrench.
  • Page 13 GENERAL INFORMATION 1-5 Before Servicing Ball Bearing and Needle Bearing Do not remove pressed ball or needle unless removal is absolutely necessary. Replace with new ones whenever removed. Press bearings with the manufacturer and size marks facing out. Press the bearing into place by putting pressure on the correct bearing race as shown.
  • Page 14 1-6 GENERAL INFORMATION Before Servicing Direction of Engine Rotation When rotating the crankshaft by hand, the free play amount of rotating direction will affect the adjustment. Ro- tate the crankshaft to positive direction (clockwise viewed from output side). Electrical Leads A two-color lead is identified first by the primary color and then the stripe color.
  • Page 15: Model Identification

    GENERAL INFORMATION 1-7 Model Identification KX250YB Left Side View KX250YB Right Side View Frame Number Engine Number...
  • Page 16: General Specifications

    1-8 GENERAL INFORMATION General Specifications KX250YB ∼ YC Items Dimensions Overall Length 2 170 mm (85.43 in.) Overall Width 820 mm (32.3 in.) Overall Height 1 270 mm (50.00 in.) Wheelbase 1 475 mm (58.07 in.) Road Clearance 330 mm (13.0 in.) Seat Height 945 mm (37.2 in.) Curb Mass:...
  • Page 17 GENERAL INFORMATION 1-9 General Specifications KX250YB ∼ YC Items Engine Oil: Grade API SG, SH, SJ, SL or SM with JASO MA, MA1 or MA2 Viscosity SAE 10W-40 Capacity 1.0 L (1.1 US qt) Drive Train Primary Reduction System: Type Gear Reduction Ratio 3.350 (67/20)
  • Page 18 1-10 GENERAL INFORMATION General Specifications KX250YB ∼ YC Items Effective Disc Diameter: Front 225 mm (8.86 in.) Rear 215 mm (8.46 in.) Specifications are subject to change without notice, and may not apply to every country.
  • Page 19: Technical Information - Dual Injector

    Technical Information - Dual Injector Overview Although the Kawasaki Ninja super-sports models are already equipped with dual injectors, the 2012 KX250YC is the first motocross model to adopt dual-injector technology. The dual injectors are installed in the throttle body and intake duct.
  • Page 20 1-12 GENERAL INFORMATION Technical Information - Dual Injector Image of the fuel injection field A. Throttle Opening B. Engine Speed C. Fuel Injection Field of Both Injector...
  • Page 21: Unit Conversion Table

    GENERAL INFORMATION 1-13 Unit Conversion Table Prefixes for Units: Units of Length: × 0.6214 mile Prefix Symbol Power × 3.281 mega × 1 000 000 × 0.03937 kilo × 1 000 centi × 0.01 Units of Torque: milli × 0.001 micro µ...
  • Page 23: Periodic Maintenance

    PERIODIC MAINTENANCE 2-1 Periodic Maintenance Table of Contents Periodic Maintenance Chart ....................Torque and Locking Agent...................... Specifications ......................... 2-10 Special Tools .......................... 2-13 Periodic Maintenance Procedures..................2-15 Fuel System......................... 2-15 Fuel Hose and Connections Inspection ................2-15 Throttle Grip (Throttle Cable) Free Play Inspection ............2-15 Throttle Grip (Throttle Cable) Free Play Adjustment............
  • Page 24 2-2 PERIODIC MAINTENANCE Brakes..........................2-37 Brake Lever and Pedal Adjustment .................. 2-37 Brake Fluid Level Inspection..................... 2-38 Brake Fluid Change ......................2-39 Brake Pad Wear Inspection ....................2-41 Brake Master Cylinder Rubber Parts Replacement ............2-41 Caliper Rubber Parts Replacement .................. 2-42 Brake Hoses and Connections Inspection ................
  • Page 25: Periodic Maintenance Chart

    PERIODIC MAINTENANCE 2-3 Periodic Maintenance Chart The maintenance must be done in accordance with this chart to keep the motorcycle in good running condition. FREQUENCY Each Every Every 6 Every 12 race 3 races races races or or 2.5 or 7.5 or 15 Page 30 hours...
  • Page 26 2-4 PERIODIC MAINTENANCE Periodic Maintenance Chart FREQUENCY Each Every Every 6 Every 12 race 3 races races races or or 2.5 or 7.5 or 15 Page 30 hours OPERATION hours hours hours • Wheels/tires - inspect 2-32 • Rear sprocket - inspect † 2-36 •...
  • Page 27: Torque And Locking Agent

    PERIODIC MAINTENANCE 2-5 Torque and Locking Agent Tighten all bolts and nuts to the proper torque using an accurate torque wrench. If insufficiently tightened, a bolt or nut may become damaged, strip an internal thread, or break and then fall out. The following table lists the tightening torque for the major bolts and nuts, and the parts requiring use of a non-permanent locking agent or silicone grease etc.
  • Page 28 2-6 PERIODIC MAINTENANCE Torque and Locking Agent Torque Fastener Remarks N·m kgf·m ft·lb Cylinder Head Bolts (M10) S, MO Cylinder Head Bolts (M6) 106 in·lb Plug Throttle Body Clamp Screw 0.20 18 in·lb Throttle Body Holder Clamp Screw 0.20 18 in·lb Cylinder Bolt 106 in·lb Camshaft Chain Tensioner Cap Bolt...
  • Page 29 PERIODIC MAINTENANCE 2-7 Torque and Locking Agent Torque Fastener Remarks N·m kgf·m ft·lb Kick Pedal Bolt Kick Ratchet Guide Bolt 0.90 78 in·lb Ratchet Plate Bolt 87 in·lb L, S Ratchet Plate Screw L, S Shift Drum Cam Bolt Gear Positioning Lever Nut 0.90 78 in·lb Shift Pedal Bolt...
  • Page 30 2-8 PERIODIC MAINTENANCE Torque and Locking Agent Torque Fastener Remarks N·m kgf·m ft·lb Left Front Fork Adjuster Assembly Pressure Relief Screws 0.13 12 in·lb Right Front Fork Top Plug Right Front Fork Piston Rod Nut Right Front Fork Bottom Plug Swingarm Pivot Shaft Nut Rocker Arm Pivot Nut G, R...
  • Page 31 PERIODIC MAINTENANCE 2-9 Torque and Locking Agent Basic Torque for General Fasteners Threads Torque diameter (mm) N·m kgf·m ft·lb 3.4 ∼ 4.9 0.35 ∼ 0.50 30 ∼ 43 in·lb 5.9 ∼ 7.8 0.60 ∼ 0.80 52 ∼ 69 in·lb 14 ∼ 19 1.4 ∼...
  • Page 32: Specifications

    2-10 PERIODIC MAINTENANCE Specifications Item Standard Service Limit Fuel System 2 ∼ 3 mm (0.08 ∼ 0.12 in.) Throttle Grip Free Play – – – Idle Speed 2 050 ±50 r/min (rpm) – – – Air Cleaner Element Oil High quality foam air filter oil –...
  • Page 33 PERIODIC MAINTENANCE 2-11 Specifications Item Standard Service Limit Wheels/Tires Rim Runout (with tire installed): Axial TIR 1.0 mm (0.04 in.) or less TIR 2.0 mm (0.08 in.) Radial TIR 1.0 mm (0.04 in.) or less TIR 2.0 mm (0.08 in.) Tires Air Pressure (Front/Rear) 100 kPa (1.00 kgf/cm², 14 psi) –...
  • Page 34 2-12 PERIODIC MAINTENANCE Specifications Item Standard Service Limit 130 ∼ 500 mL Capacity (Right Front Fork) 155 ±2.5 mL (5.24 ±0.085 US oz.) (4.4 ∼ 16.9 US oz.) (KX250YB) 205 ±2.5 mL (6.93 ±0.085 US oz.) (KX250YB) 130 ∼ 492 mL (KX250YC) (4.4 ∼...
  • Page 35: Special Tools

    PERIODIC MAINTENANCE 2-13 Special Tools Inside Circlip Pliers: Fork Piston Rod Puller, M10 × 1.0: 57001-143 57001-1298 Steering Stem Nut Wrench: Filler Cap Driver: 57001-1100 57001-1454 Jack: Fork Spring Compressor: 57001-1238 57001-1587 Attachment Jack: Jack Attachment: 57001-1252 57001-1608 Fork Oil Level Gauge: Top Plug Wrench, 50 mm: 57001-1290 57001-1645...
  • Page 36 2-14 PERIODIC MAINTENANCE Special Tools Clamp: Base and Extension Rod: 57001-1693 57001-1753...
  • Page 37: Periodic Maintenance Procedures

    PERIODIC MAINTENANCE 2-15 Periodic Maintenance Procedures Fuel System Fuel Hose and Connections Inspection ○ If the motorcycle is not properly handled, the high pres- sure inside the fuel line can cause fuel to leak [A] or the hose burst. Replace the fuel hose if any fraying, cracks [B] or bulges [C] are noticed.
  • Page 38: Throttle Body Cleaning

    2-16 PERIODIC MAINTENANCE Periodic Maintenance Procedures Throttle Body Cleaning • Check the throttle bore for cleanliness as follows. ○ Remove the throttle body assy (see Throttle Body Assy Removal in the Fuel System (DFI) chapter). ○ Check the throttle bore [A] at the throttle valve for carbon deposits by opening the throttle valve.
  • Page 39: Idle Speed Inspection

    PERIODIC MAINTENANCE 2-17 Periodic Maintenance Procedures Idle Speed Inspection NOTICE This motorcycle is designed for competition use only. Therefore, the radiator does not incorporate a coolant reserve tank or cooling fan. Prolonged idling of the engine with no airflow through the radiator can cause coolant loss and engine over- heating resulting in possible engine damage.
  • Page 40: Air Cleaner Element Cleaning And Inspection

    2-18 PERIODIC MAINTENANCE Periodic Maintenance Procedures Air Cleaner Element Cleaning and Inspection NOTE ○ In dusty areas, the element should be cleaned more frequently than recommended interval. ○ After riding through rain or on muddy roads, the element should be cleaned immediately. ○...
  • Page 41 PERIODIC MAINTENANCE 2-19 Periodic Maintenance Procedures • Clean the element [A] in a bath of a high-flash point sol- vent using a soft bristle brush. • Squeeze it dry in a clean towel [A]. Do not wring the ele- ment or blow it dry; the element can be damaged. •...
  • Page 42: Fuel Tank Clean

    2-20 PERIODIC MAINTENANCE Periodic Maintenance Procedures Fuel Tank Clean WARNING Gasoline and low-flash point solvents can be flammable and/or explosive and cause severe burns. Clean the tank in a well-ventilated area, and take care that there are no sparks or flame any- where near the working area.
  • Page 43: Coolant Deterioration Inspection

    PERIODIC MAINTENANCE 2-21 Periodic Maintenance Procedures • Check the coolant level. The coolant level [A] should be at the bottom of the filler neck [B]. If the coolant level is low, add coolant through the filler opening to the bottom of the filler neck. Install the cap. Recommended Coolant Permanent type antifreeze (soft water and ethylene glycol plus corrosion and rust inhibitor chemicals for...
  • Page 44: Water Hoses And Connections Inspection

    2-22 PERIODIC MAINTENANCE Periodic Maintenance Procedures Water Hoses and Connections Inspection • Remove the radiator shroud (see Radiator Removal in the Cooling System chapter). ○ The high pressure inside the water hoses [A] can cause coolant to leak [B] or the hose to burst if the line is not properly maintained.
  • Page 45: Valve Clearance Adjustment

    PERIODIC MAINTENANCE 2-23 Periodic Maintenance Procedures • Using a thickness gauge [A], measure the clearance be- tween each cam lobe and valve lifter for all 4 valves. ○ For the purpose of adjusting the valve clearances, record the measured values. Valve Clearance Standard: 0.17 ∼...
  • Page 46: Adjustment Shims

    2-24 PERIODIC MAINTENANCE Periodic Maintenance Procedures Adjustment Shims Thick- Thick- P/No. Mark P/No. Mark ness ness 2.500 92180-0167 3.025 92180-0188 2.525 92180-0168 3.050 92180-0189 2.550 92180-0169 3.075 92180-0190 2.575 92180-0170 3.100 92180-0191 2.600 92180-0171 3.125 92180-0192 2.625 92180-0172 3.150 92180-0193 2.650 92180-0173 3.175...
  • Page 47: Cylinder Head Warp Inspection

    PERIODIC MAINTENANCE 2-25 Periodic Maintenance Procedures Cylinder Head Warp Inspection • Remove the cylinder head (see Cylinder Head Removal in the Engine Top End chapter). • Lay a straightedge [A] across the lower surface of the head at several different points, and measure warp by inserting a thickness gauge between the straightedge and the head.
  • Page 48: Piston/Cylinder Clearance Inspection

    2-26 PERIODIC MAINTENANCE Periodic Maintenance Procedures Piston/Cylinder Clearance Inspection The piston-to-cylinder clearance is measured whenever a piston or cylinder is replaced with a new one. The standard piston-to-cylinder clearance must be adhered to whenever the cylinder is replaced. If only a piston is replaced, the clearance may exceed the standard slightly.
  • Page 49: Clutch

    PERIODIC MAINTENANCE 2-27 Periodic Maintenance Procedures • Insert the new silencer wool [A] and muffler cover [B]. ○ Fit the muffler pipe end [C] and the exhaust hole of the baffle. • Apply a non-permanent locking agent to the muffler cover bolts, and tighten them.
  • Page 50: Clutch Plates Inspection

    2-28 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Remove the number plate (see Front Fork Removal in the Suspension chapter). • Loosen the locknut [A] at the clutch cable, and turn the adjusting nut [B] so that clutch lever has 8 ∼ 13 mm (0.3 ∼...
  • Page 51: Engine Oil Change

    PERIODIC MAINTENANCE 2-29 Periodic Maintenance Procedures Engine Oil Change • Warm up the engine thoroughly so that the oil will pick up any sediment and drain easily. Then stop the engine. • Place an oil pan beneath the engine. • Remove the oil filler plug [A].
  • Page 52: Oil Filter Change

    2-30 PERIODIC MAINTENANCE Periodic Maintenance Procedures Oil Filter Change • Drain: Engine Oil (see Engine Oil Change) • Remove: Oil Filter Cap Bolts [A] Oil Filter Cap [B] • Remove the oil filter [A]. • Replace the oil filter with a new one. •...
  • Page 53: Crankshaft/Transmission

    PERIODIC MAINTENANCE 2-31 Periodic Maintenance Procedures Crankshaft/Transmission Crankshaft Inspection • Remove: Cylinder Head (see Cylinder Head Removal in the En- gine Top End chapter) Cylinder (see Cylinder Removal in the Engine Top End chapter) Piston (see Piston Removal in the Engine Top End chap- ter) •...
  • Page 54: Tires Inspection

    2-32 PERIODIC MAINTENANCE Periodic Maintenance Procedures Tires Inspection • Remove any imbedded stones or other foreign particles from the tread. Repair or replace with a new one if necessary. • Visually inspect the tire for cracks and cuts. Replace the tire, if any damage are noticed. ○...
  • Page 55: Wheel Bearing Inspection

    PERIODIC MAINTENANCE 2-33 Periodic Maintenance Procedures • Set a dial gauge against the side of the rim, and rotate the rim to measure the axial runout [A]. ○ The difference between the highest and lowest dial read- ings is the amount of runout. •...
  • Page 56: Drive Chain Slack Inspection

    2-34 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Stretch the chain taut by hanging a 10 kg (22 lb) weight [A] on the chain. • Measure the length of 20 links [B] on the straight part [C] of the chain from the pin center of the 1st pin to the pin center of the 21st pin.
  • Page 57: Drive Chain Slack Adjustment

    PERIODIC MAINTENANCE 2-35 Periodic Maintenance Procedures Drive Chain Slack Adjustment • Loosen the left and right chain adjuster locknuts [A]. • Remove the cotter pin [B] and loosen the axle nut [C]. If the chain is too tight, back out the left and right chain adjusting bolts [D] evenly, and push the wheel forward until the chain is too loose.
  • Page 58: Drive Chain Lubrication

    2-36 PERIODIC MAINTENANCE Periodic Maintenance Procedures Drive Chain Lubrication ○ The chain should be lubricated with a lubricant which will both prevent the exterior from rusting and also absorb shock and reduce friction in the interior of the chain. If the chain is especially dirty, it should be washed in diesel oil or kerosene, and afterward soaked in a heavy oil.
  • Page 59: Brakes

    PERIODIC MAINTENANCE 2-37 Periodic Maintenance Procedures Brakes Brake Lever and Pedal Adjustment • Slide the dust cover [A]. • Adjust the brake lever to suit you. ○ Loosen the adjuster locknut [B] and turn the adjuster [C] to either side. •...
  • Page 60: Brake Fluid Level Inspection

    2-38 PERIODIC MAINTENANCE Periodic Maintenance Procedures Brake Fluid Level Inspection • Check the brake fluid level in the front or rear brake reser- voir [A] and the front or rear reservoir must be kept above the lower level line [B]. NOTE ○...
  • Page 61: Brake Fluid Change

    PERIODIC MAINTENANCE 2-39 Periodic Maintenance Procedures Brake Fluid Change WARNING When working with the disc brake, observe the pre- cautions listed below. 1. Never reuse old brake fluid. 2. Do not use fluid from a container that has been left unsealed or that has been open for a long time.
  • Page 62 2-40 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Remove the rubber cap [A] on the bleed valve [B]. • Attach a clear plastic hose [A] to the bleed valve on the caliper, and run the other end of the hose into a container. •...
  • Page 63: Brake Pad Wear Inspection

    PERIODIC MAINTENANCE 2-41 Periodic Maintenance Procedures Brake Pad Wear Inspection • Check the lining thickness and condition of the brake pads in each caliper. NOTE ○ It is able to check with the pads installed. If either pad is damaged, replace both pads in the caliper as a set.
  • Page 64: Caliper Rubber Parts Replacement

    2-42 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Slide the dust cover [A] on the push rod [B] out of place, and remove the circlip [C]. Special Tool - Inside Circlip Pliers: 57001-143 • Pull out the push rod. • Take off the piston assy [D]. Assembly •...
  • Page 65 PERIODIC MAINTENANCE 2-43 Periodic Maintenance Procedures • Separate the caliper holder [A] from the caliper [B]. • Remove the anti-rattle spring [C]. • Using compressed air, remove the pistons. One way to remove the pistons is as follows. ○ Cover the caliper opening with a clean, heavy cloth [A]. ○...
  • Page 66 2-44 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Using compressed air, remove the piston. ○ Cover the caliper opening with a clean, heavy cloth [A]. ○ Remove the piston by lightly applying compressed air [B] to the hose joint opening. WARNING The piston in the brake caliper can crush hands and fingers.
  • Page 67 PERIODIC MAINTENANCE 2-45 Periodic Maintenance Procedures • Install the anti-rattle springs [A] as shown in the figure. • Replace the shaft rubber boot [A] and dust boot [B] if they are damaged. • Apply a thin coat of PBC (Poly Butyl Cuprysil) grease to the caliper holder shafts [C] and holder holes (PBC is a special high-temperature, water-resistance grease).
  • Page 68: Brake Hoses And Connections Inspection

    2-46 PERIODIC MAINTENANCE Periodic Maintenance Procedures Brake Hoses and Connections Inspection • Inspect the brake hose and fittings for deterioration, cracks and signs of leakage. ○ The high pressure inside the brake line can cause fluid to leak [A] or the hose to burst if the line is not properly main- tained.
  • Page 69: Suspension

    PERIODIC MAINTENANCE 2-47 Periodic Maintenance Procedures • Remove the front/rear brake hose banjo bolts [A] and washers [B]. • Replace the washers with new ones. ○ When removing the brake hose, take care not to spill the brake fluid on the painted or plastic parts. ○...
  • Page 70 2-48 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Remove: Bolts [A] and Brake Hose Clamp [B] Bolts [C] and Guard [D] Caliper Mounting Bolts [E] Front Wheel (see Front Wheel Removal in the Wheels/Tires chapter) ○ Rest the caliper [A] on a stand [B] so that it does not dan- gle.
  • Page 71 PERIODIC MAINTENANCE 2-49 Periodic Maintenance Procedures • Unscrew the left front fork cylinder unit [A] from the outer tube [B]. Special Tool - Top Plug Wrench, 50 mm: 57001-1645 • Slowly slide down the outer tube. • Hold the left front fork tube [A] upside down over a clean container [B] and drain the oil.
  • Page 72 2-50 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Remove the push rod [A]. NOTICE Removing the locknut and pushing the piston rod thread into the left front fork cylinder unit will dam- age the oil seal. Do not remove the locknut from the piston rod.
  • Page 73 PERIODIC MAINTENANCE 2-51 Periodic Maintenance Procedures • Hold the left front fork cylinder unit [A] upside down over a clean container [B] and drain the oil. NOTE ○ Pump the piston rod up and down to discharge the fork oil. •...
  • Page 74 2-52 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Apply fork oil to the sliding surface of the piston rod. • Purge the air from the fork cylinder [A] by gently moving [B] the piston rod up and down several times. • With the piston rod fully stretched, check the oil level in the left front fork cylinder unit.
  • Page 75 PERIODIC MAINTENANCE 2-53 Periodic Maintenance Procedures • Hold the top plug wrench [A] with a vise. • Hold the left front fork cylinder unit [B] with the top plug wrench. • Tighten the left front fork base valve assembly [C]. Special Tool - Top Plug Wrench, 50 mm: 57001-1645 Torque - Left Front Fork Base Valve Assembly: 30 N·m (3.1 kgf·m, 22 ft·lb)
  • Page 76 2-54 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Protect the piston rod end with a heavy cloth to prevent damage. • Check the piston rod for smooth operation. ○ Pump the piston rod [A] to full stroke [B] by pushing down the left front fork cylinder unit [C].
  • Page 77 PERIODIC MAINTENANCE 2-55 Periodic Maintenance Procedures • Wipe the fork oil off completely from the left front fork cylin- der unit [A]. • Install the left front fork cylinder unit into the fork. • Temporarily tighten the left front fork cylinder unit using the top plug wrench.
  • Page 78 2-56 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Turn the locknut [A] counterclockwise until it contacts with the left front fork adjuster assembly [B]. • With the locknut held immovable using a wrench, tighten the left front fork adjuster assembly locknut. Torque - Left Front Fork Adjuster Assembly Locknut: 22 N·m (2.2 kgf·m, 16 ft·lb) •...
  • Page 79 PERIODIC MAINTENANCE 2-57 Periodic Maintenance Procedures Right Front Fork • Check the position of the right front fork spring preload adjuster [A] so that it can be installed in the original posi- tion. • Turn [B] the right front fork spring preload adjuster to the softest position.
  • Page 80 2-58 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Insert the compression shaft [A] and screw the extension rod [B]. • Set the other side compression shaft same process. • Screw the extension rods [A] into the base [B]. • Install the nuts [A]. •...
  • Page 81 PERIODIC MAINTENANCE 2-59 Periodic Maintenance Procedures • Unscrew the piston rod nut [A]. • Remove the spring guide [B] and fork spring [C]. • Hold the right front fork tube [A] upside down over a clean container [B] and drain the oil. NOTE ○...
  • Page 82 2-60 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Install the spring guide. • Install the piston rod nut [A] with the unthread side down. Piston Rod [B] • Screw the piston rod nut [A] onto the piston rod [B] as shown in the figure. 13 mm (0.51 in.) [C] •...
  • Page 83 PERIODIC MAINTENANCE 2-61 Periodic Maintenance Procedures • Set the right front fork tube on the base [A] as shown in the figure. Special Tool - Base and Extension Rod: 57001-1753 • Insert the compression shaft [A] and screw the extension rod [B].
  • Page 84 2-62 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Turn the piston rod nut [A] counterclockwise until it con- tacts the top plug [B]. • Holding the right front fork spring preload adjuster [C] with a wrench [D], tighten the piston rod nut. Torque - Right Front Fork Piston Rod Nut: 20 N·m (2.0 kgf·m, 15 ft·lb) •...
  • Page 85: Rear Shock Absorber Oil Change

    PERIODIC MAINTENANCE 2-63 Periodic Maintenance Procedures The torque of left front fork cylinder unit and front fork top plug are specified to 34 N·m (3.5 kgf·m, 25 ft·lb), however, when you use the top plug wrench [A], reduce the torque to 90% of the specified value [31 N·m (3.1 kgf·m, 23 ft·lb)] due to the distance [B] between the center of the square hole, where the torque wrench [C] is fitted, and that of the...
  • Page 86 2-64 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Using the press, push the reservoir cap [A]. • Remove: Circlip Reservoir Cap • Tap [A] evenly at the holes [B] in the stopper [C] with suit- able tools [D] to free the stopper from the rear shock body. •...
  • Page 87 PERIODIC MAINTENANCE 2-65 Periodic Maintenance Procedures • Hold the lower of the piston rod assembly in a vise with soft jaws or a heavy cloth. • Remove the locknut [A] and discard it. NOTICE Do not tighten the rebound damping adjuster of the piston rod.
  • Page 88 2-66 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Remove the rebound rubber [A] out of its groove [B]. • Remove: Collar [C] Spring Holder [D] Oil Seal [E] • Remove: Oil Seal [A] NOTICE To avoid damage to the surfaces of the oil seal as- sembly body [B], cover the screwdriver [D] with the cloth [C].
  • Page 89 PERIODIC MAINTENANCE 2-67 Periodic Maintenance Procedures • Inspect the piston rod sliding surface [A]. If the sliding surface is scratches or distortion, replace it. • Hold the lower of the piston rod assembly in a vise with soft jaws or heavy cloth. •...
  • Page 90 2-68 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Install: Compression Side Washers [A] Piston [B] Rebound Side Washers [C] Stopper [D] New Locknut [E] • Tighten: Torque - Piston Rod Locknut: 37 N·m (3.8 kgf·m, 27 ft·lb) ○ Install the piston direction as shown in the figure. Locknut Side Face [A] •...
  • Page 91 PERIODIC MAINTENANCE 2-69 Periodic Maintenance Procedures • Push the bladder into the gas reservoir slowly until it just clears the circlip groove. Wipe out any spilled oil. • Check the circlip for weakening, deformity and flaws. If necessary, replace it with a new one. WARNING Pressurized nitrogen gas can explode out of the shock reservoir cap if a weakened, deformed or...
  • Page 92 2-70 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Push the seal assembly into the rear shock body until it just clears the circlip groove. Replace the circlip with a new one. • Fit the circlip [A] into the groove in the rear shock body [B].
  • Page 93: Swingarm And Uni-Trak Linkage Inspection

    PERIODIC MAINTENANCE 2-71 Periodic Maintenance Procedures • Add the specified oil up to the damping adjuster assembly hole neck [A]. NOTE ○ Hold the adjuster assembly hole facing up and turn the shock absorber to bleed the air from the reservoir com- pletely.
  • Page 94: Swingarm And Uni-Trak Linkage Pivot Lubrication

    2-72 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Pump the seat down and up [A] 4 or 5 times, and inspect the smooth stroke. If the uni-trak linkage does not smooth stroke or noise is found, inspect the uni-trak linkage bearings. •...
  • Page 95 PERIODIC MAINTENANCE 2-73 Periodic Maintenance Procedures • Unlock the clamp [A] of the number plate [B]. • Remove the bolt [C]. • Clear the holes [D] and remove the number plate. • Remove the pad cover [E] and pad. • Remove: Handlebar Clamp Bolts [A] Handlebar Clamps [B]...
  • Page 96: Steering Stem Bearing Lubrication

    2-74 PERIODIC MAINTENANCE Periodic Maintenance Procedures • Check the steering again. If the steering is too tight or too loose, repeat the adjust- ment as mentioned above. • Install the handlebar (see Handlebar Installation in the Steering chapter). • Install the handlebar pad cover [A] and pad as shown in the figure.
  • Page 97: Electrical System

    PERIODIC MAINTENANCE 2-75 Periodic Maintenance Procedures Electrical System Spark Plug Cleaning and Inspection • Remove the ignition coil (see Ignition Coil Removal in the Electrical System chapter). • Clean the plug hole, using the compressed air [A]. • Remove the spark plug [A] using a 16 mm (0.63 in.) plug wrench [B].
  • Page 98: Nut, Bolt, And Fastener Tightness Inspection

    2-76 PERIODIC MAINTENANCE Periodic Maintenance Procedures Points: Lubricate with Grease. Clutch Inner Cable Upper and Lower Ends [A] Throttle Inner Cable Upper End Brake Lever Pivot Bolt Clutch Lever Pivot Bolt Brake Pedal Bolt Cables: Lubricate with Rust Inhibitor. Throttle Inner Cables Clutch Inner Cable Pivots: Lubricate with engine oil.
  • Page 99 PERIODIC MAINTENANCE 2-77 Periodic Maintenance Procedures If there are loose fasteners, retorque them to the specified torque following the specified tightening sequence. Refer to the Torque and Locking Agent section of the General Information chapter for torque specifications. For each fastener, first loosen it by 1/2 turn, then tighten it.
  • Page 101 FUEL SYSTEM (DFI) 3-1 Fuel System (DFI) Table of Contents Exploded View........................DFI System..........................3-10 DFI Parts Location........................3-20 Specifications ......................... 3-22 Special Tools and Sealant ...................... 3-24 DFI Servicing Precautions ...................... 3-26 DFI Servicing Precautions ....................3-26 Troubleshooting the DFI System .................... 3-27 Outline..........................
  • Page 102 3-2 FUEL SYSTEM (DFI) Fuel Injector Removal ....................... 3-77 Fuel Injector Installation ....................3-78 Fuel Injector Audible Inspection..................3-79 Fuel Injector Resistance Inspection .................. 3-79 Fuel Injector Power Supply Voltage Inspection..............3-80 Fuel Injector Output Voltage Inspection ................3-81 Injector Fuel Line Inspection ..................... 3-82 Upstream Injector (Service Code 42) (KX250YC Model) ............
  • Page 103 FUEL SYSTEM (DFI) 3-3 This page intentionally left blank.
  • Page 104: Exploded View

    3-4 FUEL SYSTEM (DFI) Exploded View...
  • Page 105 FUEL SYSTEM (DFI) 3-5 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb TORX Screw 3.43 0.350 30.4 in·lb Throttle Pulley Cover Bolts 0.35 30 in·lb Throttle Cable Mounting Bolts 0.36 31 in·lb Throttle Case Mounting Screws 0.38 33 in·lb Air Cleaner Element Wing Bolt 0.12 11 in·lb Air Cleaner Duct Mounting Bolt...
  • Page 106 3-6 FUEL SYSTEM (DFI) Exploded View KX250YB Model...
  • Page 107 FUEL SYSTEM (DFI) 3-7 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Water Temperature Sensor 106 in·lb Fuel Pump Bolts 87 in·lb L, S Gear Position Switch Screws 0.30 26 in·lb 4. ECU 5. Fuel Pump 6. Vehicle-down Sensor 7. Ignition Coil 8.
  • Page 108 3-8 FUEL SYSTEM (DFI) Exploded View KX250YC Model...
  • Page 109 FUEL SYSTEM (DFI) 3-9 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Water Temperature Sensor 106 in·lb Fuel Pump Bolts 87 in·lb L, S Gear Position Switch Screws 0.30 26 in·lb 4. ECU 5. Fuel Pump 6. Vehicle-down Sensor 7. Ignition Coil 8.
  • Page 110: Dfi System

    3-10 FUEL SYSTEM (DFI) DFI System DFI System (KX250YB Model)
  • Page 111 FUEL SYSTEM (DFI) 3-11 DFI System 1. Capacitor 2. ECU 3. Gear Position Switch 4. Water Temperature Sensor 5. Crankshaft Sensor 6. Vehicle-down Sensor 7. Ignition Coil 8. Fuel Tank 9. Fuel Pump 10. Pressure Regulator 11. Intake Air Pressure Sensor 12.
  • Page 112 3-12 FUEL SYSTEM (DFI) DFI System DFI System (KX250YC Model)
  • Page 113 FUEL SYSTEM (DFI) 3-13 DFI System 1. Fuel Tank 2. Fuel Pump 3. Pressure Regulator 4. Intake Air Pressure Sensor 5. Downstream Injector 6. Upstream Injector 7. Intake Air Temperature Sensor 8. Air Cleaner Housing 9. Ignition Coil 10. Vehicle-down Sensor 11.
  • Page 114 3-14 FUEL SYSTEM (DFI) DFI System DFI System Wiring Diagram (KX250YB Model)
  • Page 115 12. Ignition Coil 13. Fuel Pump 14. Vehicle-down Sensor 15. Gear Position Switch 16. Capacitor 17. Crankshaft Sensor 18. Engine Stop Switch 19. Kawasaki Diagnostic System Connector ○ Color Codes: BK: Black GY: Gray PU: Purple BL: Blue LB: Light Blue...
  • Page 116 3-16 FUEL SYSTEM (DFI) DFI System DFI System Wiring Diagram (KX250YC Model)
  • Page 117 13. Ignition Coil 14. Fuel Pump 15. Vehicle-down Sensor 16. Gear Position Switch 17. Capacitor 18. Crankshaft Sensor 19. Engine Stop Switch 20. Kawasaki Diagnostic System Connector ○ Color Codes: BK: Black GY: Gray PU: Purple BL: Blue LB: Light Blue...
  • Page 118 32. External Communication Line 14. Fuel Pump Power Supply Voltage 33. Unused 15. Fuel Pump 34. Engine Stop Switch 16. Injector 35. Ground for ECU 17. Unused 36. Ground for ECU 18. Ignition Coil *: KDS (Kawasaki Diagnostic System) 19. Unused 20. Unused...
  • Page 119 12. Power Supply to Sensors 30. Engine Stop Switch 13. External Communication Line 31. Unused 14. External Communication Line 32. Self-Diagnosis 15. Main Throttle Sensor 33. Ground for Control System 16. Vehicle-down Sensor *: KDS (Kawasaki Diagnostic System) 17. Ground for Sensors 18. Unused...
  • Page 120: Dfi Parts Location

    3-20 FUEL SYSTEM (DFI) DFI Parts Location ECU [A] FI Warning Indicator Light Harness Connector [B] Kawasaki Diagnostic System Connector [C] FI Warning Indicator Light Assembly [A] (Option) FI Warning Indicator Light Connector [B] (Option) Fuel Pump [A] Throttle Body Assy [B]...
  • Page 121 FUEL SYSTEM (DFI) 3-21 DFI Parts Location Fuel Injector [A] (KX250YB Model) Intake Air Pressure Sensor [B] Downstream Injector [A] (KX250YC Model) Upstream Injector [A] (KX250YC Model)
  • Page 122: Specifications

    3-22 FUEL SYSTEM (DFI) Specifications Item Standard Digital Fuel Injection System Idle Speed 2 050 ±50 r/min (rpm) Throttle Body Assy: Throttle Valve Single throttle valve Bore 43 (1.69 in.) ECU: Make KEIHIN Type Digital memory type, with built in IC igniter, sealed with resin Fuel Pressure (High Pressure Line) 294 kPa (3.0 kgf/cm², 43 psi) with engine idling Fuel Pump: Type...
  • Page 123 FUEL SYSTEM (DFI) 3-23 Specifications Item Standard Gear Position Switch: Resistance see text Vehicle-down Sensor: More than 55 ∼ 75° for each bank Detection Angle DC 4.75 ∼ 5.25 V Input Voltage With sensor tilted 55 ∼ 75° or more right or left: DC 3.7 Output Voltage ∼...
  • Page 124: Special Tools And Sealant

    3-24 FUEL SYSTEM (DFI) Special Tools and Sealant Oil Pressure Gauge, 5 kgf/cm²: Needle Adapter Set: 57001-125 57001-1457 Fork Oil Level Gauge: Throttle Sensor Setting Adapter: 57001-1290 57001-1538 Vacuum Gauge: Sensor Harness Adapter: 57001-1369 57001-1561 Hand Tester: Fuel Pressure Gauge Adapter: 57001-1394 57001-1593 Filler Cap Driver:...
  • Page 125 FUEL SYSTEM (DFI) 3-25 Special Tools and Sealant Measuring Adapter: Liquid Gasket, TB1211: 57001-1700 56019-120...
  • Page 126: Dfi Servicing Precautions

    3-26 FUEL SYSTEM (DFI) DFI Servicing Precautions DFI Servicing Precautions There are a number of important precautions that should be followed servicing the DFI system. ○ Connect these connectors until they click [A]. ○ Never any of the DFI electrical connectors are discon- nected.
  • Page 127: Troubleshooting The Dfi System

    FUEL SYSTEM (DFI) 3-27 Troubleshooting the DFI System Outline When an abnormality in the system occurs, the condition of the problem is stored in the memory of the ECU (Elec- tronic Control Unit). With the engine stopped and conduct a self-diagnosis inspection, the service code is indicated by the number of times the FI warning indicator light (option) blinks.
  • Page 128 3-28 FUEL SYSTEM (DFI) Troubleshooting the DFI System ○ After measurement, remove the needle adapters and ap- ply silicone sealant to the seals [A] of the connector [B] for waterproofing. Sealant - Liquid Gasket, TB1211: 56019-120 • Always check the connected battery condition before re- placing the DFI parts.
  • Page 129 FUEL SYSTEM (DFI) 3-29 Troubleshooting the DFI System ○ When checking a harness [A] for short circuit, open one end [B] and check the continuity between the other end [C] and ground [D]. If there is continuity, the harness has a short circuit to ground, and it must be repaired or re- placed.
  • Page 130: Inquiries To Rider

    3-30 FUEL SYSTEM (DFI) Troubleshooting the DFI System DFI Diagnosis Flow Chart Inquiries to Rider ○ Each rider reacts to problems in different ways, so it is important to confirm what kind of symptoms the rider has encountered. ○ Try to find out exactly what problem occurred under exactly what conditions by asking the rider; knowing this information may help you reproduce the problem.
  • Page 131 FUEL SYSTEM (DFI) 3-31 Troubleshooting the DFI System Sample Diagnosis Sheet Rider name Model Engine No. Frame No. Date problem occurred Environment when problem occurred. □ □ □ □ □ □ Weather fine, cloudy, rain, snow, always, other: □ □ □...
  • Page 132 3-32 FUEL SYSTEM (DFI) Troubleshooting the DFI System □ Poor running spark plug loose (tighten it). or no power at □ spark plug dirty, broken, or gap maladjusted (remedy it). high speed □ spark plug incorrect (replace it). □ knocking (fuel poor quality or incorrect). □...
  • Page 133: Dfi System Troubleshooting Guide

    FUEL SYSTEM (DFI) 3-33 DFI System Troubleshooting Guide NOTE ○ This is not an exhaustive list, giving every possible cause for each problem listed. It is meant simply as a rough guide to assist the troubleshooting for some of the more common difficulties in DFI system.
  • Page 134 3-34 FUEL SYSTEM (DFI) DFI System Troubleshooting Guide Symptoms or Possible Causes Actions (chapter) Intake air pressure sensor trouble Inspect (see chapter 3). Water temperature sensor trouble Inspect (see chapter 3). Intake air temperature sensor trouble Inspect (see chapter 3). Throttle sensor trouble Inspect (see chapter 3).
  • Page 135: Poor Running Or No Power At High Speed

    FUEL SYSTEM (DFI) 3-35 DFI System Troubleshooting Guide Symptoms or Possible Causes Actions (chapter) Surge: Unstable fuel pressure Fuel pressure regulator trouble (Inspect and replace fuel pump) or kinked fuel line (Inspect and replace fuel pump) (see chapter 3). Fuel injector trouble Inspect (see chapter 3).
  • Page 136 3-36 FUEL SYSTEM (DFI) DFI System Troubleshooting Guide Symptoms or Possible Causes Actions (chapter) Water temperature sensor trouble Inspect (see chapter 3). Intake air temperature sensor trouble Inspect (see chapter 3). Throttle sensor trouble Inspect (see chapter 3). Knocking: Fuel poor quality or incorrect Fuel charge (Use the gasoline recommended in the Owner’s Manual).
  • Page 137: Self-Diagnosis

    FUEL SYSTEM (DFI) 3-37 Self-Diagnosis Self-diagnosis Outline The self-diagnosis system has three modes and can be switched to another mode by grounding the self-diagnosis terminal. User Mode The ECU connected FI warning indicator light (option) goes on when DFI system and ignition system parts are faulty.
  • Page 138 3-38 FUEL SYSTEM (DFI) Self-Diagnosis • Connect the power supply harness (option P/No. 26011 -0246) [A] to the capacitor lead connector [B] of the main harness. • Connect the power supply harness (option P/No. 26011 -0246) to the 12 V battery [C] as shown in the figure. •...
  • Page 139 FUEL SYSTEM (DFI) 3-39 Self-Diagnosis Self-Diagnosis Flow Chart...
  • Page 140: How To Read Service Codes

    3-40 FUEL SYSTEM (DFI) Self-Diagnosis How to Read Service Codes ○ Service codes are shown by a series of long and short blinks of the FI warning indicator light as shown below. ○ Read 10th digit and unit digit as the FI warning indicator light blinks. ○...
  • Page 141: Service Code Table

    FUEL SYSTEM (DFI) 3-41 Self-Diagnosis Service Code Table Ser- vice FI Warning Indicator Light Problems Code Throttle sensor malfunction, wiring open or short Intake air pressure sensor malfunction, wiring open or short Intake air temperature sensor malfunction, wiring open or short Water temperature sensor malfunction, wiring open or short Crankshaft sensor malfunction, wiring open or...
  • Page 142: Backups

    3-42 FUEL SYSTEM (DFI) Self-Diagnosis Backups ○ The ECU takes the following measures to prevent engine damage when the DFI or the ignition system parts have troubles. Service Output Signal Usable Parts Backups by ECU Codes Range or Criteria If the throttle sensor system fails (the signal is out of the usable range, wiring short or open), the ECU locks ignition timing into the ignition Throttle Sensor Output...
  • Page 143 FUEL SYSTEM (DFI) 3-43 Self-Diagnosis Note: (1) D-J Method and α - N Method: When the engine load is light like at idling or low speed, the ECU determines the injection quantity by calculating from the throttle vacuum (intake air pressure sen- sor output voltage) and engine speed (crankshaft sensor output voltage).
  • Page 144: Throttle Sensor (Service Code 11)

    3-44 FUEL SYSTEM (DFI) Throttle Sensor (Service Code 11) The throttle sensor is a rotating variable resistor that change output voltage according to throttle operating. The ECU senses this voltage change and determines fuel injection quantity, and ignition timing according to engine rpm, and throttle opening.
  • Page 145 FUEL SYSTEM (DFI) 3-45 Throttle Sensor (Service Code 11) • Replace the O-ring [A] and throttle sensor [B]. • Apply engine oil to the new O-ring and assemble it on the new throttle sensor. • Engage the groove [A] in the inner rotor of the throttle sensor with the throttle shaft [B].
  • Page 146 3-46 FUEL SYSTEM (DFI) Throttle Sensor (Service Code 11) • Connect the throttle sensor setting adapter [A] between the harness connector [B] and throttle sensor connector [C]. Special Tool - Throttle Sensor Setting Adapter: 57001 -1538 • Connect a digital meter [D] to the throttle sensor setting adapter lead.
  • Page 147: Throttle Sensor Input Voltage Inspection

    FUEL SYSTEM (DFI) 3-47 Throttle Sensor (Service Code 11) • Adjust position of the sensor so that the output voltage is within the specified voltage range. Throttle Sensor Output Voltage DC 0.58 ∼ 0.62 V Standard: If the input voltage reading shows other than 5 V, calculate a valid output voltage range as follows: Example: In the case of an input voltage of 4.75 V...
  • Page 148 3-48 FUEL SYSTEM (DFI) Throttle Sensor (Service Code 11) • Disconnect the throttle sensor connector and connect the throttle sensor setting adapter [A] between these connec- tors. Harness Connector [B] Throttle Sensor Connector [C] Special Tool - Throttle Sensor Setting Adapter: 57001 -1538 •...
  • Page 149: Throttle Sensor Output Voltage Inspection

    FUEL SYSTEM (DFI) 3-49 Throttle Sensor (Service Code 11) If the reading is out of the standard, remove the ECU and check the wiring for continuity between main harness and sub harness connectors. ○ Disconnect the ECU and sensor connectors. Wiring Inspection ECU Connector [A] ←→...
  • Page 150 3-50 FUEL SYSTEM (DFI) Throttle Sensor (Service Code 11) • Measure the output voltage with the engine stopped, and with the connector joined. • Connect the power supply harness (option P/No. 26011 -0246) and 12 V battery to the capacitor lead connector (see Throttle Sensor Input Voltage Inspection).
  • Page 151: Throttle Sensor Resistance Inspection

    FUEL SYSTEM (DFI) 3-51 Throttle Sensor (Service Code 11) Throttle Sensor Resistance Inspection • Disconnect the throttle sensor connector. • Connect throttle sensor setting adapter [A] to the throttle sensor. Special Tool - Throttle Sensor Setting Adapter: 57001 -1538 • Connect a digital meter to the throttle sensor setting adapter leads.
  • Page 152 3-52 FUEL SYSTEM (DFI) Throttle Sensor (Service Code 11) Throttle Sensor Circuit (KX250YC Model) 1. ECU 2. Throttle Sensor...
  • Page 153: Intake Air Pressure Sensor (Service Code 12)

    FUEL SYSTEM (DFI) 3-53 Intake Air Pressure Sensor (Service Code 12) Intake Air Pressure Sensor Removal NOTICE Never drop the intake air pressure sensor, espe- cially on a hard surface. Such a shock to the sensor can damage it. • Remove: Fuel Tank (see Fuel Tank Removal) Fuel Hose (see Fuel Hose Replacement in the Periodic...
  • Page 154: Intake Air Pressure Sensor Input Voltage Inspection

    3-54 FUEL SYSTEM (DFI) Intake Air Pressure Sensor (Service Code 12) Intake Air Pressure Sensor Input Voltage Inspection NOTE ○ Be sure the battery is fully charged. • Disconnect the intake air pressure sensor connector and connect the sensor harness adapter [A] between these connectors.
  • Page 155: Intake Air Pressure Sensor Output Voltage Inspection

    FUEL SYSTEM (DFI) 3-55 Intake Air Pressure Sensor (Service Code 12) If the reading is out of the standard, remove the ECU and check the wiring for continuity between main harness and sub harness connectors. ○ Disconnect the ECU and sensor connectors. Wiring Inspection ECU Connector [A] ←→...
  • Page 156 3-56 FUEL SYSTEM (DFI) Intake Air Pressure Sensor (Service Code 12) If the reading is within the usable range, remove the ECU and check the wiring for continuity between main harness and sub harness connectors. ○ Disconnect the ECU and sensor connectors. Wiring Inspection ECU Connector [A] ←→...
  • Page 157 FUEL SYSTEM (DFI) 3-57 Intake Air Pressure Sensor (Service Code 12) then Pv = Pl – Pg For example, suppose the following data is obtained: Pg = 8 cmHg (Vacuum Gauge Reading) Pl = 70 cmHg (Barometer Reading) Vv = 3.2 V (Digital Meter Reading) then Pv = 70 –...
  • Page 158 3-58 FUEL SYSTEM (DFI) Intake Air Pressure Sensor (Service Code 12) ID: Idling Ps: Standard Atmospheric Pressure (Absolute) Pv: Throttle Vacuum Pressure (Absolute) ST: Standard of Sensor Output Voltage (V) TO: Throttle Full Open UR: Usable Range of Sensor Output Voltage (V) Vv: Intake Air Pressure Sensor Output Voltage (V) (Digital Meter Reading)
  • Page 159 FUEL SYSTEM (DFI) 3-59 Intake Air Pressure Sensor (Service Code 12) Intake Air Pressure Sensor Circuit (KX250YB Model) 1. ECU 2. Intake Air Pressure Sensor Intake Air Pressure Sensor Circuit (KX250YC Model) 1. ECU 2. Intake Air Pressure Sensor...
  • Page 160: Intake Air Temperature Sensor (Service Code 13)

    3-60 FUEL SYSTEM (DFI) Intake Air Temperature Sensor (Service Code 13) Intake Air Temperature Sensor Removal/Instal- lation NOTICE Never drop the intake air temperature sensor, espe- cially on a hard surface. Such a shock to the sensor can damage it. •...
  • Page 161 FUEL SYSTEM (DFI) 3-61 Intake Air Temperature Sensor (Service Code 13) • Disconnect the capacitor lead connector [A]. • Connect the power supply harness (option P/No. 26011 -0246) [A] to the capacitor lead connector [B] of the main harness. • Connect the power supply harness (option P/No.
  • Page 162: Intake Air Temperature Sensor Resistance Inspection

    3-62 FUEL SYSTEM (DFI) Intake Air Temperature Sensor (Service Code 13) If the reading is out of the standard, remove the ECU and check the wiring for continuity between main harness and sub harness connectors. ○ Disconnect the ECU and sensor connectors. Wiring Inspection ECU Connector [A] ←→...
  • Page 163 FUEL SYSTEM (DFI) 3-63 Intake Air Temperature Sensor (Service Code 13) Intake Air Temperature Sensor Circuit (KX250YB Model) 1. ECU 2. Intake Air Temperature Sensor Intake Air Temperature Sensor Circuit (KX250YC Model) 1. ECU 2. Intake Air Temperature Sensor...
  • Page 164: Water Temperature Sensor (Service Code 14)

    3-64 FUEL SYSTEM (DFI) Water Temperature Sensor (Service Code 14) Water Temperature Sensor Removal/Installation NOTICE Never drop the water temperature sensor, espe- cially on a hard surface. Such a shock to the sensor can damage it. • Drain the coolant (see Coolant Draining in the Cooling System chapter).
  • Page 165 FUEL SYSTEM (DFI) 3-65 Water Temperature Sensor (Service Code 14) • Connect the power supply harness (option P/No. 26011 -0246) [A] to the capacitor lead connector [B] of the main harness. • Connect the power supply harness (option P/No. 26011 -0246) to the 12 V battery [C] as shown.
  • Page 166: Water Temperature Sensor Inspection

    3-66 FUEL SYSTEM (DFI) Water Temperature Sensor (Service Code 14) Water Temperature Sensor Inspection • Remove the water temperature sensor (see Water Tem- perature Sensor Removal/Installation). • Suspend the sensor [A] in a container of machine oil so that the heat-sensitive portion and threaded portion are submerged.
  • Page 167 FUEL SYSTEM (DFI) 3-67 Water Temperature Sensor (Service Code 14) Water Temperature Sensor Circuit (KX250YC Model) 1. ECU 2. Water Temperature Sensor...
  • Page 168: Crankshaft Sensor (Service Code 21)

    3-68 FUEL SYSTEM (DFI) Crankshaft Sensor (Service Code 21) The crankshaft sensor has no power source, and when the engine stops, the crankshaft sensor generates no sig- nals. Crankshaft Sensor Removal/Installation • Refer to the Starter Coil Removal/Installation in the Elec- trical System chapter.
  • Page 169 FUEL SYSTEM (DFI) 3-69 Crankshaft Sensor (Service Code 21) Crankshaft Sensor Circuit 1. ECU 2. Crankshaft Sensor...
  • Page 170: Gear Position Switch (Service Code 25)

    3-70 FUEL SYSTEM (DFI) Gear Position Switch (Service Code 25) Gear Position Switch Removal • Remove: Left Radiator Shroud (see Radiator Removal in the Cool- ing System chapter) Shift Pedal (External Shift Mechanism Removal in the Crankshaft/Transmission chapter) Gear Position Switch Connector [A] •...
  • Page 171: Gear Position Switch Inspection

    FUEL SYSTEM (DFI) 3-71 Gear Position Switch (Service Code 25) Gear Position Switch Inspection NOTE ○ Be sure the transmission mechanism is good condition. • Remove the left radiator shroud (see Radiator shroud Re- moval in the Frame chapter). • Disconnect the gear position switch lead connector [A].
  • Page 172 3-72 FUEL SYSTEM (DFI) Gear Position Switch (Service Code 25) Gear Position Switch Circuit 1. ECU 2. Frame Ground 3. Gear Position Switch...
  • Page 173: Vehicle-Down Sensor (Service Code 31)

    FUEL SYSTEM (DFI) 3-73 Vehicle-down Sensor (Service Code 31) When the motorcycle is down, the engine stops according to the condition of the below table. Engine Speed Time Engine Condition 2 500 rpm or less After 30 seconds Stop 2 500 rpm or more After 3 seconds Stop When the vehicle-down sensor is broken, the engine will...
  • Page 174 3-74 FUEL SYSTEM (DFI) Vehicle-down Sensor (Service Code 31) • Disconnect the capacitor lead connector [A]. • Connect the power supply harness (option P/No. 26011 -0246) [A] to the capacitor lead connector [B] of the main harness. • Connect the power supply harness (option P/No. 26011 -0246) to the 12 V battery [C] as shown.
  • Page 175: Vehicle-Down Sensor Output Voltage Inspection

    FUEL SYSTEM (DFI) 3-75 Vehicle-down Sensor (Service Code 31) Vehicle-down Sensor Output Voltage Inspection • Remove the vehicle-down sensor. ○ Remove the vehicle-down sensor, and connect the mea- suring adapter [A]. Special Tool - Measuring Adapter: 57001-1700 Main Harness [B] Vehicle-down Sensor [C] •...
  • Page 176 3-76 FUEL SYSTEM (DFI) Vehicle-down Sensor (Service Code 31) If the reading is within the standard, remove the ECU and check the wiring for continuity between main harness side connectors. ○ Disconnect the ECU and sensor connectors. Wiring Inspection ECU Connector [A] ←→ Vehicle-down Sensor Connector [B] KX250YB Model [C] BR lead [D] (ECU terminal 2)
  • Page 177: Fuel Injector (Service Code 41)

    FUEL SYSTEM (DFI) 3-77 Fuel Injector (Service Code 41) NOTE ○ Service code 41 indicates downstream injector in the KX250YC model. NOTICE Never drop the fuel injector, especially on a hard surface. Such a shock to the injector can damage Fuel Injector Removal •...
  • Page 178: Fuel Injector Installation

    3-78 FUEL SYSTEM (DFI) Fuel Injector (Service Code 41) Fuel Injector Installation • Replace the dust seal [B] with a new one. • Apply silicone grease or engine oil to the O-ring [A] and dust seal. • Assemble the delivery pipe [A] and the fuel injector [B]. •...
  • Page 179: Fuel Injector Audible Inspection

    FUEL SYSTEM (DFI) 3-79 Fuel Injector (Service Code 41) Fuel Injector Audible Inspection • Remove: Left Radiator Shroud (see Radiator Removal in the Cool- ing System chapter) • Start the engine, and let it idle. • Apply the tip of a screwdriver [A] to the fuel injector. Put the grip end into your ear, and listen whether the fuel in- jector is clicking or not.
  • Page 180: Fuel Injector Power Supply Voltage Inspection

    3-80 FUEL SYSTEM (DFI) Fuel Injector (Service Code 41) Fuel Injector Power Supply Voltage Inspection NOTE ○ Be sure the battery is fully charged. • Disconnect the injector connector and connect the mea- suring adapter [A] between these connector. Main Harness [B] Fuel Injector [C] Special Tool - Measuring Adapter: 57001-1700 •...
  • Page 181: Fuel Injector Output Voltage Inspection

    FUEL SYSTEM (DFI) 3-81 Fuel Injector (Service Code 41) Fuel Injector Output Voltage Inspection NOTE ○ Be sure the battery is fully charged. • Remove the ECU (see ECU Removal). ○ Do not disconnect the ECU connector. • Connect the power supply harness (option P/No. 26011 -0246) and 12 V battery to the capacitor lead connector (see Fuel Injector Power Supply Voltage Inspection).
  • Page 182: Injector Fuel Line Inspection

    3-82 FUEL SYSTEM (DFI) Fuel Injector (Service Code 41) Injector Fuel Line Inspection • Remove: Fuel Tank (see Fuel Tank Removal) Fuel Hose (see Fuel Hose Replacement in the Periodic Maintenance chapter) ○ Be sure to place a piece of cloth around the fuel outlet pipe of fuel pump and delivery pipe of throttle body assy.
  • Page 183 FUEL SYSTEM (DFI) 3-83 Fuel Injector (Service Code 41) Fuel Injector Circuit (KX250YB Model) 1. ECU 2. Fuel Injector 3. Frame Ground 4. Capacitor Fuel Injector Circuit (KX250YC Model) 1. ECU 2. Downstream Injector 3. Frame Ground 4. Capacitor...
  • Page 184: Upstream Injector (Service Code 42) (Kx250Yc Model)

    3-84 FUEL SYSTEM (DFI) Upstream Injector (Service Code 42) (KX250YC Model) NOTICE Never drop the upstream injector, especially on a hard surface. Such a shock to the upstream injector can damage it. Upstream Injector Removal • Remove: Rear Frame (see Rear Frame Removal in the Frame chapter) •...
  • Page 185: Upstream Injector Resistance Inspection

    FUEL SYSTEM (DFI) 3-85 Upstream Injector (Service Code 42) (KX250YC Model) • Fit the projection [A] on the delivery pipe to the hollow [B] of the air cleaner housing. ○ Face the connector side to front side. • Apply a non-permanent locking agent to the threads of the delivery joint bolt [A].
  • Page 186: Upstream Injector Power Supply Voltage Inspection

    3-86 FUEL SYSTEM (DFI) Upstream Injector (Service Code 42) (KX250YC Model) Upstream Injector Power Supply Voltage Inspection NOTE ○ Be sure the battery is fully charged. • Disconnect the upstream injector connector and connect the measuring adapter [A] between these connector. Main Harness [B] Upstream Injector [C] Special Tool - Measuring Adapter: 57001-1700...
  • Page 187: Upstream Injector Output Voltage Inspection

    FUEL SYSTEM (DFI) 3-87 Upstream Injector (Service Code 42) (KX250YC Model) Upstream Injector Output Voltage Inspection NOTE ○ Be sure the battery is fully charged. • Remove the ECU (see ECU Removal). ○ Do not disconnect the ECU connector. • Connect the power supply harness (option P/No.
  • Page 188: Upstream Injector Fuel Line Inspection

    3-88 FUEL SYSTEM (DFI) Upstream Injector (Service Code 42) (KX250YC Model) Upstream Injector Fuel Line Inspection • Remove: Fuel Hose (see Rear Frame Removal in the Frame chap- ter) ○ Be sure to place a piece of cloth around the delivery pipe of air cleaner housing.
  • Page 189 FUEL SYSTEM (DFI) 3-89 Upstream Injector (Service Code 42) (KX250YC Model) Upstream Injector Circuit 1. ECU 2. Upstream Injector 3. Frame Ground 4. Capacitor...
  • Page 190: Fuel Pump (Service Code 46)

    3-90 FUEL SYSTEM (DFI) Fuel Pump (Service Code 46) Fuel Pump Removal WARNING Gasoline is extremely flammable and can be ex- plosive under certain conditions. Always stop the engine and do not smoke. Make sure the area is well-ventilated and free from any source of flame or sparks;...
  • Page 191: Fuel Pump Operation Inspection

    FUEL SYSTEM (DFI) 3-91 Fuel Pump (Service Code 46) • Install the fuel pump [A] to the fuel tank. • Apply a non-permanent locking agent to the threads of the fuel pump bolts. • Gradually tighten the fuel pump bolts evenly following the specified tightening sequence [1 ∼...
  • Page 192: Fuel Pump Operating Voltage Inspection

    3-92 FUEL SYSTEM (DFI) Fuel Pump (Service Code 46) Fuel Pump Operating Voltage Inspection NOTE ○ Be sure the battery is fully charged. • Remove the left radiator shroud (see Radiator Removal in the Cooling System chapter). • Disconnect the fuel pump lead connector and connect the harness adapter [A] between these connectors as shown.
  • Page 193: Pressure Regulator Removal

    FUEL SYSTEM (DFI) 3-93 Fuel Pump (Service Code 46) Pressure Regulator Removal ○ The pressure regulator [A] is built into the fuel pump and can not be removed. Fuel Filter Cleaning ○ The fuel filter [A] is built into the pump and can not be cleaned or checked.
  • Page 194 3-94 FUEL SYSTEM (DFI) Fuel Pump (Service Code 46) Fuel Pump Circuit (KX250YC Model) 1. ECU 2. Frame Ground 3. Fuel Pump 4. Capacitor...
  • Page 195: Ignition Coil (Service Code 51)

    FUEL SYSTEM (DFI) 3-95 Ignition Coil (Service Code 51) Ignition Coil Removal/Installation • Refer to the Ignition Coil Removal/Installation in the Elec- trical System chapter. Ignition Coil Input Voltage Inspection • Refer to the Ignition Coil Peak Voltage Inspection in the Electrical System chapter.
  • Page 196: Ecu

    3-96 FUEL SYSTEM (DFI) ECU Identification ○ Most countries have their own regulations, so each ECU has different characteristic. So, do not confuse ECU with each other and use only the ECU for your model. Other- wise, the motorcycle cannot clear the regulation. ECU Identification (KX250YB Model) Part Number [A] Specification...
  • Page 197: Ecu Installation

    FUEL SYSTEM (DFI) 3-97 ECU Installation • Install the ECU [B] to the rubber protector [A]. • Insert the slits [A] of the rubber protector to the air cleaner housing bracket. • Connect the ECU connector [B]. ECU Power Supply Inspection •...
  • Page 198 3-98 FUEL SYSTEM (DFI) • Disconnect the ECU connector [A]. • Set the hand tester [B] to the × 1 Ω range and check the following wiring for continuity. Special Tool - Hand Tester: 57001-1394 ECU Grounding Inspection ECU Connector ←→ Capacitor Connector [C] KX250YB Model [D] BK/W lead [E] (ECU terminal 8)
  • Page 199 FUEL SYSTEM (DFI) 3-99 • Connect a digital meter [A] to the connector [B] with the needle adapter set. KX250YB Model [C] KX250YC Model [D] Special Tool - Needle Adapter Set: 57001-1457 ECU Power Supply Inspection Connections: Digital Meter (+) → Terminal 1 (R/W lead) Digital Meter (–) →...
  • Page 200: Fuel Line

    3-100 FUEL SYSTEM (DFI) Fuel Line Fuel Pressure Inspection NOTE ○ Be sure the battery is fully charged. • Remove: Radiator Shroud (see Radiator Removal in the Cooling System chapter) Fuel Tank (see Fuel Tank Removal) Fuel Hose (see Fuel Injector Removal) ○...
  • Page 201 FUEL SYSTEM (DFI) 3-101 Fuel Line • Connect the power supply harness (option P/No. 26011 -0246) [A] to the capacitor lead connector [B] of the main harness. • Connect the power supply harness (option P/No. 26011 -0246) to the 12 V battery [C] as shown. NOTE ○...
  • Page 202: Fuel Flow Rate Inspection

    3-102 FUEL SYSTEM (DFI) Fuel Line Fuel Flow Rate Inspection WARNING Gasoline is extremely flammable and can be ex- plosive under certain conditions. Always stop the engine and do not smoke. Make sure the area is well-ventilated and free from any source of flame or sparks;...
  • Page 203 FUEL SYSTEM (DFI) 3-103 Fuel Line • Disconnect the capacitor lead connector [A]. • Connect the power supply harness (option P/No. 26011 -0246) [A] to the capacitor lead connector [B] of the main harness. • Connect the power supply harness (option P/No. 26011 -0246) to the 12 V battery [C] as shown then, drive the fuel pump and fuel goes out.
  • Page 204: Throttle Grip And Cable

    3-104 FUEL SYSTEM (DFI) Throttle Grip and Cable If the throttle grip has excessive free play due to cable stretch or misadjustment, there will be a delay in throttle re- sponse. Also, the throttle valve may not open fully at full throttle.
  • Page 205: Throttle Cable Lubrication

    FUEL SYSTEM (DFI) 3-105 Throttle Grip and Cable • Loosen the mounting bolts [A]. • Remove the cables [B] from the throttle body assy. • Free the tips [C] from the pulley. • Pull out the cables from the frame. •...
  • Page 206: Throttle Body Assy

    3-106 FUEL SYSTEM (DFI) Throttle Body Assy Idle Speed Inspection • Refer to the Idle Speed Inspection in the Periodic Main- tenance chapter. Throttle Bore Cleaning • Refer to the Throttle Body Cleaning in the Periodic Main- tenance chapter. Throttle Body Assy Removal WARNING Gasoline is extremely flammable and can be ex- plosive under certain conditions.
  • Page 207: Throttle Body Assy Installation

    FUEL SYSTEM (DFI) 3-107 Throttle Body Assy Throttle Body Assy Installation • Install the throttle body assy so that fit the projection [B] on throttle body assy and groove [A] of the throttle body holder. • Install the removed parts (see appropriate chapters). •...
  • Page 208: Throttle Body Assy Assembly

    3-108 FUEL SYSTEM (DFI) Throttle Body Assy • Pull out the injector [A] from the delivery pipe [B]. NOTE ○ Do not damage the insertion portions of the injector when they are pulled out from the delivery pipe. NOTICE Never drop the fuel injector, especially on a hard surface.
  • Page 209 FUEL SYSTEM (DFI) 3-109 Throttle Body Assy • Replace the O-ring [A] of delivery pipe [B] with a new one. • Apply silicone grease or engine oil to the O-ring. • Install the delivery pipe in the joint [C], and tighten the screw securely.
  • Page 210 3-110 FUEL SYSTEM (DFI) Throttle Body Assy • Install the plate so that fit the hollow [A] on the plate and projection [B] on the throttle body assy. • Install the vacuum hose [C]. • Tighten the plate mounting screws securely.
  • Page 211: Air Cleaner

    FUEL SYSTEM (DFI) 3-111 Air Cleaner Air Cleaner Housing Removal • Remove the rear frame (see Rear Frame Removal in the Frame chapter). • Remove the air cleaner housing bolts [A]. • Take the air cleaner housing off the rear frame. Air Cleaner Housing Installation •...
  • Page 212: Fuel Tank

    3-112 FUEL SYSTEM (DFI) Fuel Tank Fuel Tank Removal WARNING Gasoline is extremely flammable and can be ex- plosive under certain conditions. Always stop the engine and do not smoke. Make sure the area is well-ventilated and free from any source of flame or sparks;...
  • Page 213: Fuel Tank Installation

    FUEL SYSTEM (DFI) 3-113 Fuel Tank • Pull [B] the fuel hose joint [A] out of the fuel outlet pipe. WARNING Fuel is flammable and explosive under certain con- ditions and can cause severe burns. Be prepared for fuel spillage; any spilled fuel must be completely wiped up immediately.
  • Page 214: Fuel Tank Cleaning

    3-114 FUEL SYSTEM (DFI) Fuel Tank • Push and pull [B] the hose joint [A] back and forth more than two times, and make sure it is locked and does not come off. WARNING Leaking fuel can cause a fire or explosion resulting in serious burns.
  • Page 215 COOLING SYSTEM 4-1 Cooling System Table of Contents Exploded View........................Specifications ......................... Special Tool ..........................Coolant ........................... Coolant Level Inspection....................Coolant Deterioration Inspection..................Coolant Draining ....................... Coolant Filling ........................Air Bleeding........................Cooling System Pressure Testing ..................Cooling System Flushing ....................Water Pump..........................
  • Page 216: Exploded View

    4-2 COOLING SYSTEM Exploded View...
  • Page 217 COOLING SYSTEM 4-3 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Radiator Shroud Bolts 87 in·lb Radiator Mounting Bolts 87 in·lb Radiator Screen Bolts 87 in·lb Water Hose Clamp Screws 0.31 27 in·lb Water Pipe Bolt 87 in·lb Water Pump Cover Bolts (L = 55 mm) 87 in·lb Water Pump Impeller Bolt 0.71...
  • Page 218: Specifications

    4-4 COOLING SYSTEM Specifications Item Standard Coolant Permanent type antifreeze (soft water and ethylene glycol plus Type corrosion and rust inhibitor chemicals for aluminum engines and radiators) Color Green Mixed Ratio Soft water 50%, coolant 50% Freezing Point –35°C (–31°F) Total Amount 1.2 L (1.3 US qt.) Radiator...
  • Page 219: Special Tool

    COOLING SYSTEM 4-5 Special Tool Bearing Driver Set: 57001-1129...
  • Page 220: Coolant

    4-6 COOLING SYSTEM Coolant Coolant Level Inspection • Refer to the Coolant Level Inspection in the Periodic Main- tenance chapter. Coolant Deterioration Inspection • Refer to the Coolant Deterioration Inspection in the Peri- odic Maintenance chapter. Coolant Draining WARNING Coolant can be extremely hot and cause severe burns, is toxic and very slippery.
  • Page 221: Coolant Filling

    COOLING SYSTEM 4-7 Coolant Coolant Filling NOTICE Use coolant containing corrosion inhibitors made specifically for aluminum engines and radiators in accordance with the instruction of the manufac- ture’s. Soft or distilled water must be used with the antifreeze (see below for antifreeze) in the cooling system.
  • Page 222: Cooling System Pressure Testing

    4-8 COOLING SYSTEM Coolant Cooling System Pressure Testing NOTICE During pressure testing, do not exceed the pres- sure for which the system is designed to work. The maximum pressure is 123 kPa (1.25 kgf/cm², 18 psi). • Remove the radiator cap, and install a cooling system pressure tester [A] and adapter [B] on the radiator filler neck [C].
  • Page 223: Water Pump

    COOLING SYSTEM 4-9 Water Pump Water Pump Cover Removal • Remove the oil filter (see Oil Filter Change in the Periodic Maintenance chapter). ○ Drain the engine oil from the water pump cover. • Drain the coolant (see Coolant Draining). •...
  • Page 224: Impeller Removal

    4-10 COOLING SYSTEM Water Pump • Replace the water pipe O-ring [A] with a new one. • Apply soap and water solution to the new O-ring. • Insert the water pipe [B] straightly into the hole of the wa- ter pump cover. •...
  • Page 225: Water Pump Gear Removal

    COOLING SYSTEM 4-11 Water Pump • Check the drainage outlet passage [A] at the bottom of the right engine cover for coolant leaks. If the oil seal is damaged, the coolant leaks through the seal and drains through the passage. Replace the oil seals.
  • Page 226: Oil Seal And Bearing Installation

    4-12 COOLING SYSTEM Water Pump • Insert a bar [A] into the water pump shaft hole from the inside. • Remove the oil seal [B] by tapping [C] evenly around the seal lips. Oil Seal and Bearing Installation NOTICE If the oil seal or ball bearing is removed, replace all of them with new ones at the same time.
  • Page 227: Radiator

    COOLING SYSTEM 4-13 Radiator Radiator Removal • Drain the coolant (see Coolant Draining). • Remove: Radiator Shroud Bolts [A] (Both Sides) Radiator Shroud [B] (Both Sides) • Remove the capacitor [A] (see Capacitor Removal in the Electrical System chapter). • Loosen: Water Hose Clamp Screws [B] •...
  • Page 228: Radiator Installation

    4-14 COOLING SYSTEM Radiator Radiator Installation • Install: Radiators Water Hoses Washers Clutch Cable Clamps [A] (Left Side) • Tighten: Torque - Radiator Mounting Bolts: 9.8 N·m (1.0 kgf·m, 87 in·lb) Water Hose Clamp Screws: 3.0 N·m (0.31 kgf·m, 27 in·lb) •...
  • Page 229: Radiator Cap Inspection

    COOLING SYSTEM 4-15 Radiator Radiator Cap Inspection • Check the top and bottom valve seals [A] of the radiator cap, and the condition of the valve spring [B]. If any one of them shows visible damage, replace the cap. • Wet the top and bottom valve seals with water or coolant to prevent pressure leaks.
  • Page 231 ENGINE TOP END 5-1 Engine Top End Table of Contents Exploded View........Valve Installation ......5-26 Specifications ........Valve Guide Removal ....5-26 Special Tools and Sealant ....Valve Guide Installation ....5-27 Cylinder Head Cover ......5-12 Valve/Valve Guide Clearance Cylinder Head Cover Removal ..
  • Page 232: Exploded View

    5-2 ENGINE TOP END Exploded View...
  • Page 233 ENGINE TOP END 5-3 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Auto-Decompressor Bolt 106 in·lb Cylinder Head Cover Bolts 87 in·lb Camshaft Cap Bolts 87 in·lb S, MO Cylinder Head Bolts (M10) S, MO Cylinder Head Bolts (M6) 106 in·lb Plug Throttle Body Clamp Screw 0.20...
  • Page 234 5-4 ENGINE TOP END Exploded View...
  • Page 235 ENGINE TOP END 5-5 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Exhaust Pipe Cover Bolts 106 in·lb Exhaust Pipe Holder Nuts Muffler Mounting Bolts Muffler Clamp Bolt 97 in·lb L: Apply a non-permanent locking agent. LG: Apply liquid gasket. R: Replacement Parts S: Follow the specific tightening sequence.
  • Page 236: Specifications

    5-6 ENGINE TOP END Specifications Item Standard Service Limit Camshafts Cam Height: 33.943 ∼ 34.057 mm Exhaust 33.84 mm (1.3363 ∼ 1.3408 in.) (1.332 in.) 35.243 ∼ 35.357 mm Intake 35.14 mm (1.3875 ∼ 1.3920 in.) (1.383 in.) 0.020 ∼ 0.062 mm Camshaft Journal/Cap Clearance 0.15 mm (0.0008 ∼...
  • Page 237 ENGINE TOP END 5-7 Specifications Item Standard Service Limit Valve Seat Surface: Outside Diameter: 24.6 ∼ 24.8 mm Exhaust – – – (0.969 ∼ 0.976 in.) 30.6 ∼ 30.8 mm Intake – – – (1.205 ∼ 1.213 in.) Width: 0.5 ∼ 1.0 mm Exhaust –...
  • Page 238 5-8 ENGINE TOP END Specifications Cam Height Camshaft Runout Cam Height [A] Valve Stem Diameter Valve Stem Bend Valve Stem Diameter [A] Dial Gauge [A] 45° [B]...
  • Page 239: Special Tools And Sealant

    ENGINE TOP END 5-9 Special Tools and Sealant Compression Gauge, 20 kgf/cm²: Valve Seat Cutter, 45° - 32: 57001-221 57001-1115 Valve Spring Compressor Assembly: Valve Seat Cutter, 32° - 28: 57001-241 57001-1119 Piston Ring Compressor Grip: Valve Seat Cutter Holder Bar: 57001-1095 57001-1128 Piston Ring Compressor Belt, 67 ∼...
  • Page 240 5-10 ENGINE TOP END Special Tools and Sealant Compression Gauge Adapter, M10 × 1.0: Valve Seat Cutter, 60° - 33: 57001-1317 57001-1334 Valve Seat Cutter, 60° - 25: Filler Cap Driver: 57001-1328 57001-1454 Valve Seat Cutter Holder, 4.5: Valve Guide Driver: 57001-1330 57001-1564 Valve Guide Arbor, 4.5:...
  • Page 241 ENGINE TOP END 5-11 Special Tools and Sealant Valve Guide Driver Attachment, F: Liquid Gasket, TB1216B: 57001-1722 92104-1064...
  • Page 242: Cylinder Head Cover

    5-12 ENGINE TOP END Cylinder Head Cover Cylinder Head Cover Removal • Remove: Fuel Tank (see Fuel Tank Removal in the Fuel System chapter) Spark Plug Cap [A] Cylinder Head Cover Bolts [B] Cylinder Head Cover [C] • Remove the cylinder head cover gasket [A]. Cylinder Head Cover Installation •...
  • Page 243 ENGINE TOP END 5-13 Cylinder Head Cover • Install the cylinder head cover bolt washers [A] with the metal side upwards. • Tighten: Torque - Cylinder Head Cover Bolts [B]: 9.8 N·m (1.0 kgf·m, 87 in·lb) • Install the removed parts (see appropriate chapters).
  • Page 244: Camshaft Chain Tensioner

    5-14 ENGINE TOP END Camshaft Chain Tensioner Camshaft Chain Tensioner Removal NOTICE This is a non-return type camshaft chain tensioner. The push rod does not return to its original position once it moves out to take up camshaft chain slack. Observe all the rules listed below: When removing the tensioner, do not take out the mounting bolts only halfway.
  • Page 245: Camshafts

    ENGINE TOP END 5-15 Camshafts Camshaft Removal • Remove: Cylinder Head Cover (see Cylinder Head Cover Re- moval) Capacitor (see Capacitor Removal in the Electrical Sys- tem chapter) Timing Inspection Cap [A] Flywheel Nut Cap [B] Special Tool - Filler Cap Driver: 57001-1454 •...
  • Page 246: Camshaft Installation

    5-16 ENGINE TOP END Camshafts • Remove: Bolt [A] Auto-Decompressor [B] Spring [C] Camshaft Installation • When installing the spring [A] on the auto-decompressor [B], put the spring end [C] onto the outside coil as shown in the figure. • Install the auto-decompressor [A] in the exhaust camshaft.
  • Page 247 ENGINE TOP END 5-17 Camshafts • Bring the crankshaft to the TDC. ○ Place a wrench over the flywheel nut [A] and turn it coun- terclockwise to align the TDC mark [B] with the center of the groove [C] of the inspection hole. •...
  • Page 248: Camshaft Chain Removal

    5-18 ENGINE TOP END Camshafts • Install the dowel pins [A] and positioning rings [B]. • Apply molybdenum disulfide oil to the threads and seating surface of the camshaft cap bolts. • Tighten all camshaft cap bolts evenly and lightly, and then tighten them with specified torque.
  • Page 249: Camshaft Chain Installation

    ENGINE TOP END 5-19 Camshafts Camshaft Chain Installation • Engage the camshaft chain to the crankshaft. • Install the lower camshaft chain guide. • Tighten: Torque - Lower Camshaft Chain Guide Bolt: 9.8 N·m (1.0 kgf·m, 87 in·lb) • Install: Flywheel Magneto (see Flywheel Magneto Installation in the Electrical System chapter) Camshafts (see Camshaft Installation)
  • Page 250: Cam Wear Inspection

    5-20 ENGINE TOP END Camshafts Cam Wear Inspection • Remove the camshaft (see Camshaft Removal). • Measure the height [A] of each cam with a micrometer. Cam Height Standard: 33.943 ∼ 34.057 mm (1.3363 ∼ 1.3408 in.) Exhaust 35.234 ∼ 35.357 mm (1.3875 ∼ 1.3920 in.) Intake Service Limit: Exhaust...
  • Page 251: Cylinder Head

    ENGINE TOP END 5-21 Cylinder Head Cylinder Compression Measurement • Warm up the engine thoroughly. • Stop the engine. • Remove: Fuel Tank (see Fuel Tank Removal in the Fuel System chapter) Spark Plug (see Spark Plug Cleaning and Inspection in the Periodic Maintenance chapter) •...
  • Page 252: Cylinder Head Removal

    5-22 ENGINE TOP END Cylinder Head Cylinder Head Removal • Remove: Fuel Tank (see Fuel Tank Removal in the Fuel System (DFI) chapter) Camshaft Chain Tensioner (see Camshaft Chain Ten- sioner Removal) Cylinder Head Cover (see Cylinder Head Cover Re- moval) Camshaft (see Camshaft Removal) Exhaust Pipe (see Exhaust Pipe Removal)
  • Page 253: Cylinder Head Installation

    ENGINE TOP END 5-23 Cylinder Head Cylinder Head Installation • Install the front camshaft chain guide. ○ Fit the projection [A] in the groove [B] of the cylinder. ○ Insert the guide end [C] into the recess of the crankcase securely.
  • Page 254: Cylinder Head Warp Inspection

    5-24 ENGINE TOP END Cylinder Head Cylinder Head Warp Inspection • Refer to the Cylinder Head Warp Inspection in the Peri- odic Maintenance chapter.
  • Page 255: Valves

    ENGINE TOP END 5-25 Valves Valve Clearance Inspection • Refer to the Valve Clearance Inspection in the Periodic Maintenance chapter. Valve Clearance Adjustment • Refer to the Valve Clearance Adjustment in the Periodic Maintenance chapter. Valve Removal • Remove the cylinder head (see Cylinder Head Removal). •...
  • Page 256: Valve Installation

    5-26 ENGINE TOP END Valves Valve Installation • Visually inspect the valve surface. If the surface is damaged, replace the valve. • Replace the oil seal [A] with a new one. • Apply a thin coat of molybdenum disulfide grease to the valve stem [B] and install the valve.
  • Page 257: Valve Guide Installation

    ENGINE TOP END 5-27 Valves • Hammer lightly on the valve guide arbor [A] to remove the guide. Special Tool - Valve Guide Arbor, 4.5: 57001-1331 Valve Guide Installation • Apply a thin coat of engine oil to the outer surface of the valve guide.
  • Page 258: Measurement (Wobble Method)

    5-28 ENGINE TOP END Valves • Repeat the measurement in a direction at a 90° angle to the first measurement. NOTE ○ The reading is greater than the actual valve/valve guide clearance because the measurement is taken outside of the guide. Valve/Valve Guide Clearance (Wobble Method) Standard: 0.07 ∼...
  • Page 259: Valve Seat Repair

    ENGINE TOP END 5-29 Valves Valve Seat Repair • For the instructions on how to use the valve seat cutter [A], follow the operation manual provided by the tool man- ufacturer. Special Tools - Valve Seat Cutter Holder, 4.5 [B]: 57001 -1330 Valve Seat Cutter Holder Bar: 57001-1128 Exhaust:...
  • Page 260 5-30 ENGINE TOP END Valves Marks Stamped on the Cutter: The marks stamped on the back of the cutter [A] represent the following. 60° ......Cutter Angle [B] 37.5 ....... Cutter Outer Diameter [C] Repair Operating Procedures • Clean the seat area carefully. •...
  • Page 261 ENGINE TOP END 5-31 Valves If the outside diameter [A] of the seating surface is too large, make the 32° [B] grind described below. If the outside diameter of the seating surface is within the specified range, measure the seat width as described be- low.
  • Page 262 5-32 ENGINE TOP END Valves Valve Seat Repair...
  • Page 263: Cylinder And Piston

    ENGINE TOP END 5-33 Cylinder and Piston Cylinder Removal • Remove: Cylinder Head (see Cylinder Head Removal) Front Camshaft Chain Guide [A] Cylinder Bolt [B] • Tap lightly up with a plastic hammer to separate the cylin- der [C] from the crankcase. •...
  • Page 264 5-34 ENGINE TOP END Cylinder and Piston • Install the top ring [A] so that the "R" mark [B] faces up. NOTE ○ If a new piston or cylinder is used, check piston to cylin- der clearance (see Piston/Cylinder Clearance Inspec- tion in the Periodic Maintenance chapter), and use new piston rings.
  • Page 265: Cylinder Wear Inspection

    ENGINE TOP END 5-35 Cylinder and Piston • Apply engine oil to the cylinder bore and the piston side wall. • Install the cylinder while compressing the piston rings with your fingers or the special tool [A]. ○ Upturn the chamfering side of the belt. Special Tools - Piston Ring Compressor Grip: 57001-1095 67 ∼...
  • Page 266: Piston Ring Groove Width Inspection

    5-36 ENGINE TOP END Cylinder and Piston Piston Ring Groove Width Inspection • Measure the groove width at several points around the piston with a vernier caliper. Piston Ring Groove Width Standard: 0.83 ∼ 0.85 mm (0.0327 ∼ 0.335 in.) Service Limit: 0.93 mm (0.037 in.) If any of the groove widths exceeds the service limit, re-...
  • Page 267: Piston, Piston Pin, Connecting Rod Wear Inspection

    ENGINE TOP END 5-37 Cylinder and Piston Piston, Piston Pin, Connecting Rod Wear Inspection • Visually inspect the snap ring [A] still fitted in place. If the ring shows weakness or deformation, replace the ring. Also if the pin hole groove shows excessive wear, replace the piston.
  • Page 268: Throttle Body Holder

    5-38 ENGINE TOP END Throttle Body Holder Throttle Body Holder Installation • Install: Throttle Body Holder Throttle Body Holder Clamp ○ Turn the mark [A] to the throttle body assy. ○ Turn the screw head [B] to the engine left side. •...
  • Page 269: Muffler

    ENGINE TOP END 5-39 Muffler WARNING The muffler can become extremely hot during nor- mal operation and cause severe burns. Do not re- move the muffler while it is hot. Muffler Body Removal • Remove the right side cover (see Side Cover Removal in the Frame chapter).
  • Page 271 CLUTCH 6-1 Clutch Table of Contents Exploded View........................Specifications ......................... Special Tools .......................... Clutch Lever and Cable ......................Clutch Lever (Clutch Cable) Free Play Inspection ............Clutch Lever (Clutch Cable) Free Play Adjustment ............Clutch Lever Installation....................Clutch Cable Removal ...................... Clutch Cable Installation ....................
  • Page 272: Exploded View

    6-2 CLUTCH Exploded View...
  • Page 273 CLUTCH 6-3 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Clutch Cover Bolts 87 in·lb Right Engine Cover Bolts 87 in·lb Clutch Spring Bolts 0.92 80 in·lb Clutch Hub Nut Oil Filler Plug 0.51 44 in·lb CL: Apply cable lubricant. EO: Apply engine oil.
  • Page 274: Specifications

    6-4 CLUTCH Specifications Item Standard Service Limit Clutch Lever 8 ∼ 13 mm (0.3 ∼ 0.5 in.) Clutch Lever Free Play – – – Clutch 2.72 ∼ 2.88 mm (0.107 ∼ 0.113 in.) Friction Plate Thickness 2.5 mm (0.10 in.) Friction Plate Warp 0.15 mm (0.0059 in.) or less 0.3 mm (0.012 in.)
  • Page 275: Special Tools

    CLUTCH 6-5 Special Tools Inside Circlip Pliers: Clutch Holder: 57001-143 57001-1243 Bearing Driver Set: 57001-1129...
  • Page 276: Clutch Lever And Cable

    6-6 CLUTCH Clutch Lever and Cable Due to friction plate wear and clutch cable stretch over a long period of use, the clutch must be adjusted in accor- dance with the Periodic Maintenance Chart. WARNING The engine and exhaust system get extremely hot during normal operation and can cause serious burns.
  • Page 277: Clutch Cable Installation

    CLUTCH 6-7 Clutch Lever and Cable • Align the slit [A] of the adjusting nut to the slit [B] of the lever. • Free the clutch cable upper end. • Take the cable off the cable holder [A]. • Take the cable lower end [B] off the clutch release lever [C].
  • Page 278: Clutch Cover And Right Engine Cover

    6-8 CLUTCH Clutch Cover and Right Engine Cover Clutch Cover Removal • Drain the engine oil (see Engine Oil Change in the Peri- odic Maintenance chapter). • Remove: Brake Pedal Bolt [A] Brake Pedal Return Spring [B] • Remove the clutch cover bolts [A] and take off the clutch cover.
  • Page 279: Right Engine Cover Installation

    CLUTCH 6-9 Clutch Cover and Right Engine Cover • Remove: Bolt [A] Right Engine Guard [B] • Remove: Water Pump Cover (see Water Pump Cover Removal in the Cooling System chapter) Clutch Cover Bolts [A] Right Engine Cover Bolts [B] Right Engine Cover [C] Right Engine Cover Installation •...
  • Page 280: Oil Seal Installation

    6-10 CLUTCH Clutch Cover and Right Engine Cover • Pour: Engine Oil (see Engine Oil Change in the Periodic Main- tenance chapter) Coolant (see Coolant Filling in the Cooling System chap- ter) • Check the rear brake effectiveness (see Brakes section in the Periodic Maintenance chapter).
  • Page 281: Clutch Removal

    CLUTCH 6-11 Clutch Clutch Removal • Drain the engine oil (see Engine Oil Change in the Peri- odic Maintenance chapter). • Remove: Clutch Cover (see Clutch Cover Removal) Clutch Spring Bolts [A] Springs Clutch Pressure Plate [B] • Remove: Push Rod Holder Assembly [A] Friction Plates [B] Steel Plates [C] Steel Ball...
  • Page 282 6-12 CLUTCH Clutch • Install the clutch housing [A]. ○ Turn the kick idle gear and the oil pump idle gear with suitable tool [B] to fit in the clutch housing. • Install: Thrust Washer [A] Clutch Hub [B] • Hold the clutch hub with the clutch holder [A].
  • Page 283 CLUTCH 6-13 Clutch • If a clutch part was replaced, install the standard adjusting washer (1.5 mm thickness) [A] of the push rod holder as- sembly, and check the release lever position as explained later procedure. • Install the clutch pressure plate and clutch springs. •...
  • Page 284: Release Shaft Removal

    6-14 CLUTCH Clutch Release Shaft Removal • Remove: Clutch (see Clutch Removal) Clutch Cable Upper End (see Clutch Cable Removal) • Remove the tips [A] of the clutch cable. • Pull out the release shaft assembly [B]. Release Shaft Installation •...
  • Page 285: Friction Plate/Clutch Housing Clearance Inspection

    CLUTCH 6-15 Clutch Friction Plate/Clutch Housing Clearance Inspection • Measure the clearance between the tangs [A] on the fric- tion plate and the fingers [B] of the clutch housing. ○ If this clearance is excessive, the clutch will be noisy. Friction Plate/Clutch Housing Clearance 0.04 ∼...
  • Page 287 ENGINE LUBRICATION SYSTEM 7-1 Engine Lubrication System Table of Contents Exploded View........................Engine Oil Flow Chart......................Specifications ......................... Special Tools .......................... Engine Oil and Oil Filter......................Engine Oil Level Inspection ....................Engine Oil Change......................Oil Filter Replacement ...................... Oil Screen Cleaning and Inspection.................. Oil Pump..........................
  • Page 288: Exploded View

    7-2 ENGINE LUBRICATION SYSTEM Exploded View...
  • Page 289: Ft·lb

    ENGINE LUBRICATION SYSTEM 7-3 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Breather Fitting Oil Pump Mounting Bolts 0.71 62 in·lb Oil Pump Idle Gear Shaft Screws 0.60 52 in·lb Oil Filter Cap Bolts 87 in·lb Piston Oil Nozzle 0.30 26 in·lb Engine Oil Drain Bolt EO: Apply engine oil.
  • Page 290: Engine Oil Flow Chart

    7-4 ENGINE LUBRICATION SYSTEM Engine Oil Flow Chart...
  • Page 291 ENGINE LUBRICATION SYSTEM 7-5 Engine Oil Flow Chart 1. Oil Screen (scavenge) 2. Oil Screen (feed) 3. Oil Pump (scavenge) 4. Oil Pump (feed) 5. Oil Filter 6. Oil Shower to Transmission 7. Piston Oil Nozzle 8. Kick Starter Idle Gear 9.
  • Page 292: Specifications

    7-6 ENGINE LUBRICATION SYSTEM Specifications Item Standard Engine Oil Grade Castrol “POWER1 R4 Racing” 5W-40 or API SG, SH, SJ, SL or SM with JASO MA, MA1 or MA2 Viscosity SAE 10W-30, 10W-40, or 10W-50 Capacity Oil Change - when filter is not removed 0.75 L (0.79 US qt) Oil Change - when filter is removed 0.80 L (0.85 US qt)
  • Page 293: Special Tools

    ENGINE LUBRICATION SYSTEM 7-7 Special Tools Oil Pressure Gauge, 5 kgf/cm²: Oil Pressure Gauge Adapter, M6 × 1.0: 57001-125 57001-1664 Outside Circlip Pliers: 57001-144...
  • Page 294: Engine Oil And Oil Filter

    7-8 ENGINE LUBRICATION SYSTEM Engine Oil and Oil Filter WARNING Vehicle operation with insufficient, deteriorated, or contaminated engine oil will cause accelerated wear and may result in engine seizure, accident, and injury. Check the oil level before each use and change the oil and filter according to the periodic maintenance chart.
  • Page 295: Oil Filter Replacement

    ENGINE LUBRICATION SYSTEM 7-9 Engine Oil and Oil Filter Oil Filter Replacement • Refer to the Oil Filter Replacement in the Periodic Main- tenance chapter. Oil Screen Cleaning and Inspection Oil Screen (Feed) • Remove the engine (see Engine Removal in the Engine Removal/Installation chapter).
  • Page 296 7-10 ENGINE LUBRICATION SYSTEM Engine Oil and Oil Filter Oil Screen (Scavenge) • Remove the magneto cover (see Magneto Cover Re- moval in the Electrical System chapter). • Remove the oil screen (scavenge) [A]. • Clean the oil screen with a high-flash point solvent and remove any particles stuck to it.
  • Page 297: Oil Pump

    ENGINE LUBRICATION SYSTEM 7-11 Oil Pump Oil Pump Removal • Drain: Engine Oil (see Engine Oil Change in the Periodic Main- tenance chapter) Coolant (see Coolant Draining in the Cooling System chapter) • Remove: Brake Pedal (see Brake Pedal Removal in the Brakes chapter) Kick Pedal (see Kick Pedal Removal in the Crank- shaft/Transmission chapter)
  • Page 298: Oil Pump Installation

    7-12 ENGINE LUBRICATION SYSTEM Oil Pump • Disassemble the oil pump assembly. Pins [A] Oil Pump Cover [B] Inner [C] and Outer [D] Rotors (Feed) Oil Pump Body [E] Oil Pump Gear [F] Oil Pump Installation • Apply molybdenum disulfide grease to the shaft of the oil pump gear.
  • Page 299: Oil Pump Inspection

    ENGINE LUBRICATION SYSTEM 7-13 Oil Pump • Apply a non-permanent locking agent to the oil pump mounting bolts. • Tighten: Torque - Oil Pump Mounting Bolts: 7.0 N·m (0.71 kgf·m, 62 in·lb) • Apply engine oil to the shaft of the oil pump idle gear. •...
  • Page 300: Oil Pressure

    7-14 ENGINE LUBRICATION SYSTEM Oil Pressure Oil Pressure Measurement • Remove water pump cover bolt. • Install the oil pressure gauge adapter [A] to the water pump cover. Special Tool - Oil Pressure Gauge Adapter, M6 × 1.0: 57001-1664 • Attach the oil pressure gauge [A].
  • Page 301 ENGINE REMOVAL/INSTALLATION 8-1 Engine Removal/Installation Table of Contents Exploded View........................Special Tools .......................... Engine Removal/Installation ....................Engine Removal........................ Engine Installation......................
  • Page 302: Exploded View

    8-2 ENGINE REMOVAL/INSTALLATION Exploded View...
  • Page 303 ENGINE REMOVAL/INSTALLATION 8-3 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Upper Engine Mounting Bolts Upper Engine Bracket Bolts Middle Engine Mounting Nut R, S Middle Engine Bracket Nuts R, S Lower Engine Mounting Nut R, S Swingarm Pivot Shaft Nut R, S 7.
  • Page 304: Special Tools

    8-4 ENGINE REMOVAL/INSTALLATION Special Tools Jack: Jack Attachment: 57001-1238 57001-1608 Attachment Jack: 57001-1252...
  • Page 305: Engine Removal/Installation

    ENGINE REMOVAL/INSTALLATION 8-5 Engine Removal/Installation Engine Removal • Remove the engine guards. • Place the jack under the frame to support the motorcycle. Special Tools - Jack: 57001-1238 Jack Attachment :57001-1252 or 57001-1608 WARNING When the swingarm pivot shaft is removed the swingarm and rear wheel assembly will become detached and allow the frame to fall to the floor, creating the potential for injury.
  • Page 306 8-6 ENGINE REMOVAL/INSTALLATION Engine Removal/Installation • Remove: Rear Frame (see Rear Frame Removal in the Frame chapter) Exhaust Pipe (see Exhaust Pipe Removal in the Engine Top End chapter) Fuel Tank (see Fuel Tank Removal in the Fuel System (DFI) chapter) Vehicle-down Sensor (Vehicle-down Sensor Removal in the Fuel System (DFI) chapter) Radiators and Water Hoses (see Radiator Removal in...
  • Page 307: Engine Installation

    ENGINE REMOVAL/INSTALLATION 8-7 Engine Removal/Installation • Remove the following parts on both sides: Upper Engine Bracket Bolts [A] Upper Engine Mounting Bolts [B] and Nuts Upper Engine Brackets [C] • Remove: Middle Engine Bracket Bolts [A] and Nuts Middle Engine Mounting Bolt [B] and Nut Middle Engine Brackets [C] (Both Sides) Lower Engine Mounting Bolt [D] and Nut •...
  • Page 308 8-8 ENGINE REMOVAL/INSTALLATION Engine Removal/Installation KX250YC • Install the washers [A] as shown in the figure. • Insert the swingarm pivot shaft. • Install all engine brackets, bolts and nuts temporarily. ○ Insert the following bolts from left side: Middle Engine Mounting Bolt [A] Middle Engine Bracket Bolts [B] Lower Engine Mounting Bolt [C] •...
  • Page 309 ENGINE REMOVAL/INSTALLATION 8-9 Engine Removal/Installation • Install the removed parts (see appropriate chapters). • Run the cables, hoses, and leads according to the Cable, Wire and Hose Routing section in the Appendix chapter. • Fill: Engine Oil (see Engine Oil Change in the Periodic Main- tenance chapter) Coolant (see Coolant Filling in the Cooling System chap- ter)
  • Page 311 CRANKSHAFT/TRANSMISSION 9-1 Crankshaft/Transmission Table of Contents Exploded View........................Specifications ......................... Special Tools & Sealant......................Crankcase ..........................Crankcase Disassembly ....................Crankcase Assembly ......................9-10 Crankshaft ..........................9-15 Crankshaft Removal ......................9-15 Crankshaft Installation ...................... 9-15 Crankshaft Disassembly ....................9-15 Crankshaft Assembly ......................9-15 Crankshaft Inspection .......................
  • Page 312: Exploded View

    9-2 CRANKSHAFT/TRANSMISSION Exploded View...
  • Page 313 CRANKSHAFT/TRANSMISSION 9-3 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Crankcase Bolts (L = 50 mm) 87 in·lb Crankcase Bolts (L = 60 mm) 87 in·lb Crankcase Bolts (L = 65 mm) 87 in·lb Crankcase Bolts (L = 70 mm) 87 in·lb Crankcase Bearing Retainer Screws Piston Oil Nozzle...
  • Page 314 9-4 CRANKSHAFT/TRANSMISSION Exploded View...
  • Page 315 CRANKSHAFT/TRANSMISSION 9-5 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Kick Pedal Bolt Kick Ratchet Guide Bolt 0.90 78 in·lb Ratchet Plate Bolt 87 in·lb L, S Ratchet Plate Screw L, S Shift Drum Cam Bolt Gear Positioning Lever Nut 0.90 78 in·lb Shift Pedal Bolt...
  • Page 316: Specifications

    9-6 CRANKSHAFT/TRANSMISSION Specifications Item Standard Service Limit Crankshaft, Connecting Rod Connecting Rod Big End: 0.002 ∼ 0.014 mm Radial Clearance 0.06 mm (0.0024 in.) (0.00008 ∼ 0.00055 in.) 0.25 ∼ 0.35 mm (0.0098 ∼ 0.0138 in.) Side Clearance 0.6 mm (0.02 in.) Crankshaft Runout TIR 0.03 mm (0.001 in.) or less TIR 0.08 mm (0.003 in.)
  • Page 317: Special Tools & Sealant

    CRANKSHAFT/TRANSMISSION 9-7 Special Tools & Sealant Bearing Puller: Crankshaft Jig: 57001-135 57001-1174 Bearing Puller Adapter: Crankcase Splitting Tool Assembly: 57001-136 57001-1362 Outside Circlip Pliers: Gear Holder, m2.0: 57001-144 57001-1557 Bearing Driver Set: Liquid Gasket, TB1216: 57001-1129 92104-1063...
  • Page 318: Crankcase

    9-8 CRANKSHAFT/TRANSMISSION Crankcase Crankcase Disassembly • Remove the engine from the frame (see Engine Removal in the Engine Removal/Installation chapter). • Set the engine on clean surface while parts are being re- moved. • Remove: Cylinder Head Cover (see Cylinder Head Cover Re- moval in the Engine Top End chapter) Camshaft Chain Tensioner (see Camshaft Chain Ten- sioner Removal in the Engine Top End chapter)
  • Page 319 CRANKSHAFT/TRANSMISSION 9-9 Crankcase • Position the connecting rod in BDC. • Install the jig [A] between the crankshaft flywheels. Special Tool - Crankshaft Jig: 57001-1174 • Attach the crankcase splitting tool [A] to the left crankcase. ○ Adjust the gap with suitable collars or nuts [B] as shown in the figure.
  • Page 320: Crankcase Assembly

    9-10 CRANKSHAFT/TRANSMISSION Crankcase • Remove the reed valve [A] from the left crankcase half. ○ Unscrew the screws [B] and remove the guide [C]. Crankcase Assembly NOTICE Right and left crankcase halves are machined at the factory in the assembled state, so if replaced, they must be replaced as a set.
  • Page 321 CRANKSHAFT/TRANSMISSION 9-11 Crankcase • Press the new drive shaft bearing [A] so that the sealed side [B] faces outside of the engine. • Press the new output shaft bearing [C] so that the stepped side [D] faces inside of the engine. Special Tool - Bearing Driver Set: 57001-1129 •...
  • Page 322 9-12 CRANKSHAFT/TRANSMISSION Crankcase • Install the reed valve [A] and guide [B] as shown in the figure. • Tighten: Torque - Reed Valve Screws [C]: 7.0 N·m (0.71 kgf·m, 62 in·lb) Right Crankcase • Press the new crankshaft bearing [A] and new drive shaft bearing [B] until they bottom out.
  • Page 323 CRANKSHAFT/TRANSMISSION 9-13 Crankcase • Install the right crankcase bearing retainers. ○ The right crankcase bearing retainers are larger than left ones. • Apply a non-permanent locking agent to the crankcase bearing retainer screws [A]. • Tighten: Torque - Crankcase Bearing Retainer Screws: 15 N·m (1.5 kgf·m, 11 ft·lb) •...
  • Page 324 9-14 CRANKSHAFT/TRANSMISSION Crankcase • Apply liquid gasket to the mating surface [A] of the left crankshaft half. ○ Using a high-flash point solvent, clean off any oil or dirt that may be on the liquid gasket coating area. Dry them with a clean cloth.
  • Page 325: Crankshaft

    CRANKSHAFT/TRANSMISSION 9-15 Crankshaft Crankshaft Removal • Disassemble the crankcase (see Crankcase Disassem- bly). • Remove the transmission shafts (see Transmission Shaft Removal). • Using a hand press, remove the crankshaft from the right crankcase. If the bearing stay on the crankshaft when splitting the crankcase, or removing the crankshaft from the right crankcase, remove the bearings from the crankshaft with a bearing puller.
  • Page 326: Crankshaft Inspection

    9-16 CRANKSHAFT/TRANSMISSION Crankshaft • Carefully align the oil passage hole in the right flywheel [A] with the one in the crankpin [B] at rebuilding of the crankshaft as shown in the figure. • Reassemble the crankshaft according to the standard tol- erances in Specifications.
  • Page 327 CRANKSHAFT/TRANSMISSION 9-17 Crankshaft Crankshaft Runout Inspection • Set the crankshaft in a flywheel alignment jig or on V blocks, and place a dial gauge as shown and turn the crankshaft slowly. The maximum difference in gauge reading is the crankshaft runout. 8 mm (0.3 in.) [A] Crankshaft Runout Standard:...
  • Page 328: Connecting Rod Bend Inspection

    9-18 CRANKSHAFT/TRANSMISSION Crankshaft Connecting Rod Bend Inspection • Remove the connecting rod. • Select an arbor [A] of the same diameter as the connect- ing rod big end, and insert it through the connecting rod big end. • Select an arbor [B] of the same diameter as the piston pin and more than 105 mm (4.13 in.) long, and insert it through the connecting rod small end.
  • Page 329: Transmission

    CRANKSHAFT/TRANSMISSION 9-19 Transmission Transmission Shaft Removal • Disassemble the crankcase halves (see Crankcase Dis- assembly). • Pull out the shift rods [A], and take off the shift forks [B]. • Remove the shift drum [C]. • Pull out the drive shaft [D] and output shaft [E] together. Transmission Shaft Installation •...
  • Page 330: Transmission Shaft Disassembly

    9-20 CRANKSHAFT/TRANSMISSION Transmission • Install the oil screen (feed) [A] as shown in the figure. Longer Outcrop of Pipe [B] Right Crankcase [C] • Assembly the crankcase (see Crankcase Assembly). Transmission Shaft Disassembly • Remove the transmission shafts (see Transmission Shaft Removal).
  • Page 331: Shift Fork Bending Inspection

    CRANKSHAFT/TRANSMISSION 9-21 Transmission 1. Circlip (Small) 11. Ball Bearing (Right Crankcase) 2. Toothed Washer 12. Output Shaft 3. Circlip (Large) 13. Ball Bearing (Left Crankcase) 4. Ball Bearing (Left Crankcase, One 14. Collar side sealed) 15. 2nd Gear (28T) 5. 2nd Gear (16T) 16.
  • Page 332: Shift Fork/Gear Groove Wear Inspection

    9-22 CRANKSHAFT/TRANSMISSION Transmission Shift Fork/Gear Groove Wear Inspection • Measure the thickness [A] of the shift fork ears, and mea- sure the width [B] of the gear grooves (with which the fork engages). Shift Fork Ear Thickness 4.9 ∼ 5.0 mm (0.193 ∼ 0.197 in.) Standard: Service Limit: 4.8 mm (0.189 in.) Gear Groove Width...
  • Page 333: Bearings/Oil Seals

    CRANKSHAFT/TRANSMISSION 9-23 Bearings/Oil Seals Bearing Replacement NOTICE Do not remove the ball bearings unless it is neces- sary. Removal may damage them. • Remove the ball bearing and/or needle bearing outer race using a press or suitable bearing remover. NOTE ○...
  • Page 334: Oil Seal Inspection

    9-24 CRANKSHAFT/TRANSMISSION Bearings/Oil Seals • Check the needle bearing. ○ The rollers in a needle bearing normally wear very little, and wear is difficult to measure. Instead of measuring, inspect the bearing for abrasion, color change, or other damage. If there is any doubt as to the condition of a needle bear- ing, replace it.
  • Page 335: Primary Gear

    CRANKSHAFT/TRANSMISSION 9-25 Primary Gear Primary Gear Removal • Remove: Right Engine Cover (see Right Engine Cover Removal in the Clutch chapter) Clutch (see Clutch Removal in the Clutch chapter) • Temporarily install the clutch housing [A], clutch hub [B] and clutch hub nut [C]. •...
  • Page 336: External Shift Mechanism

    9-26 CRANKSHAFT/TRANSMISSION External Shift Mechanism External Shift Mechanism Removal • Remove: Shift Pedal Bolt [A] Shift Pedal [B] • Remove: Right Engine Cover (see Right Engine Cover Removal in the Clutch chapter) Clutch (see Clutch Removal in the Clutch chapter) •...
  • Page 337: External Shift Mechanism Installation

    CRANKSHAFT/TRANSMISSION 9-27 External Shift Mechanism External Shift Mechanism Installation • Install: Pin [A] Spring [B] Collar [C] Gear Positioning Lever [D] Washer [E] • Tighten: Torque - Gear Positioning Lever Nut: 8.8 N·m (0.90 kgf·m, 78 in·lb) • Hold the gear positioning lever [A] with the suitable tool [B], and install the shift drum cam [C].
  • Page 338: External Shift Mechanism Inspection

    9-28 CRANKSHAFT/TRANSMISSION External Shift Mechanism • Apply grease to the oil seal lips [A] and shift shaft splines [B]. • Insert the shift shaft [A] as shown in the figure. ○ Take care not to damage the oil seal when inserting the shift shaft.
  • Page 339 CRANKSHAFT/TRANSMISSION 9-29 External Shift Mechanism • Check the gear positioning lever [A] and its spring [B] for cracks or distortion. If the lever or spring is damaged in any way, replace them. • Visually inspect the shift drum cam [A]. If it is badly worn or if it shows any damage, replace it.
  • Page 340: Kickstarter

    9-30 CRANKSHAFT/TRANSMISSION Kickstarter Kick Pedal Removal • Remove: Kick Pedal Bolt [A] Kick Pedal Assy [B] Kick Pedal Installation • Install the kick pedal assy. ○ Put the pedal end [A] near the cylinder head mating sur- face [B]. • Apply a non-permanent locking agent to the kick pedal bolt.
  • Page 341: Kick Shaft Installation

    CRANKSHAFT/TRANSMISSION 9-31 Kickstarter • Remove the bolts [A], and take off the ratchet guide [B]. Kick Shaft Installation • Apply a non-permanent locking agent to the kick ratchet guide bolt. • Install the ratchet guide [A], and tighten the bolt. Torque - Kick Ratchet Guide Bolt [B]: 8.8 N·m (0.90 kgf·m, 78 in·lb) •...
  • Page 343 WHEELS/TIRES 10-1 Wheels/Tires Table of Contents Exploded View........................10-2 Specifications ......................... 10-4 Special Tools .......................... 10-5 Wheels (Rims) ........................10-6 Front Wheel Removal ....................... 10-6 Front Wheel Installation ....................10-6 Rear Wheel Removal......................10-7 Rear Wheel Installation..................... 10-8 Wheels Inspection......................10-9 Spoke Tightness Inspection ....................
  • Page 344: Exploded View

    10-2 WHEELS/TIRES Exploded View...
  • Page 345 WHEELS/TIRES 10-3 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Not less Not less Not less Spoke Nipples than 2.2 than 0.22 than 19 in·lb Front Axle Nut Front Axle Clamp Bolts Rear Axle Nut 11.0 AL: Tighten the two clamp bolts alternately two times to ensure even tightening torque. HG: Apply high-temperature grease.
  • Page 346: Specifications

    10-4 WHEELS/TIRES Specifications Item Standard Service Limit Wheels (Rims) Rim Size: Front 21 × 1.60 – – – Rear 19 × 1.85 – – – Rim Runout: Axial TIR 1.0 mm (0.04 in.) or less TIR 2.0 mm (0.08 in.) Radial TIR 1.0 mm (0.04 in.) or less TIR 2.0 mm (0.08 in.)
  • Page 347 WHEELS/TIRES 10-5 Special Tools Inside Circlip Pliers: Attachment Jack: 57001-143 57001-1252 Rim Protector: Bearing Remover Head, 20 × 22: 57001-1063 57001-1293 Bead Breaker Assembly: Bearing Remover Head, 25 × 28: 57001-1072 57001-1346 Bearing Driver Set: Bearing Remover Shaft, 13: 57001-1129 57001-1377 Jack: Jack Attachment:...
  • Page 348: Front Wheel Removal

    10-6 WHEELS/TIRES Wheels (Rims) Front Wheel Removal • Using the jack under the frame, and stabilize the motor- cycle. Special Tools - Jack: 57001-1238 Jack Attachment: 57001-1252 or 57001 -1608 • Loosen the axle clamp bolts [A] on both sides. •...
  • Page 349: Rear Wheel Removal

    WHEELS/TIRES 10-7 Wheels (Rims) • Pump the front fork up and down [A] 4 or 5 times to align both fork positions. NOTE ○ Put a block [B] in front of the wheel to stop moving. ○ Do not apply the front brake. •...
  • Page 350: Rear Wheel Installation

    10-8 WHEELS/TIRES Wheels (Rims) Rear Wheel Installation • Fit the groove [A] of the caliper holder and the swingarm rib [B]. • Apply high-temperature grease to the oil seal lips. • Install the caps and collars to the hub on both sides. ○...
  • Page 351: Wheels Inspection

    WHEELS/TIRES 10-9 Wheels (Rims) • Adjust the drive chain slack (see Drive Chain Slack In- spection in the Periodic Maintenance chapter). • Check the rear brake for good braking power and no brake drag. WARNING After servicing, it takes several applications of the brake pedal before the brake pads contact the disc, which could result in increased stopping distance and cause an accident resulting in injury or death.
  • Page 352: Axle Inspection

    10-10 WHEELS/TIRES Wheels (Rims) Axle Inspection • Visually inspect the front and rear axle for damages. If the axle is damaged or bent, replace it. • Place the axle on V blocks that are 100 mm (3.94 in.) [A] apart, and set a dial gauge [B] on the axle at a point halfway between the blocks.
  • Page 353: Tires

    WHEELS/TIRES 10-11 Tires Air Pressure Inspection/Adjustment • Refer to the Air Pressure Inspection/Adjustment in the Pe- riodic Maintenance chapter. Tire Removal NOTICE Do not lay the wheel directly on the ground with the disc facing down. This can damage or warp the disc.
  • Page 354: Tire Installation

    10-12 WHEELS/TIRES Tires • Break the beads away from both sides of the rim with the bead breaker [A]. Special Tool - Bead Breaker Assembly: 57001-1072 • Step on the tire opposite valve stem, pry the tire off the rim with the tire iron [A]. ○...
  • Page 355 WHEELS/TIRES 10-13 Tires • Align the valve stem [A] and the tire balance mark [B] (the chalk mark made during removal; see Tire Removal). ○ The new tire is no marked. • Insert the valve stem into the rim, and screw the nut on loosely.
  • Page 356: Hub Bearing

    10-14 WHEELS/TIRES Hub Bearing Front Hub Bearing Removal • Remove Front Wheel (see Front Wheel Removal) Grease Seals [A] • Use the bearing remover to remove the hub bearings [A]. NOTICE Do not lay the wheel on the ground with the disc facing down.
  • Page 357: Hub Bearing Installation

    WHEELS/TIRES 10-15 Hub Bearing • Using a suitable bar [A], tap the around of the bearing inner race evenly to remove the bearings [B]. Hub Bearing Installation • Before installing the hub bearings, blow any dirt or foreign particles out of the hub with compressed air to prevent contamination of the bearings.
  • Page 358: Hub Bearing Inspection

    10-16 WHEELS/TIRES Hub Bearing Hub Bearing Inspection Since the hub bearings are made to extremely close tol- erances, the clearance can not normally be measured. NOTE ○ Do not remove any bearings for inspection. If any bear- ings are removed, they will need to be replaced with new ones.
  • Page 359 FINAL DRIVE 11-1 Final Drive Table of Contents Exploded View........................11-2 Specifications ......................... 11-4 Special Tool ..........................11-5 Drive Chain..........................11-6 Drive Chain Slack Inspection .................... 11-6 Drive Chain Slack Adjustment ..................11-6 Wheel Alignment Inspection ..................... 11-6 Wheel Alignment Adjustment.................... 11-6 Drive Chain Wear Inspection ....................
  • Page 360: Exploded View

    11-2 FINAL DRIVE Exploded View...
  • Page 361 FINAL DRIVE 11-3 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Engine Sprocket Cover Bolts 0.50 43 in·lb (KX250YB Model) Engine Sprocket Cover Bolts 87 in·lb (KX250YC Model) Rear Sprocket Nuts 3. KX250YB Model 4. KX250YC Model G: Apply grease. HO: Apply heavy oil.
  • Page 362: Specifications

    11-4 FINAL DRIVE Specifications Item Standard Service Limit Drive Chain 52 ∼ 58 mm (2.0 ∼ 2.3 in.) Chain Slack – – – 317.5 ∼ 318.2 mm (12.50 ∼ 12.53 in.) Chain 20-link Length 323 mm (12.7 in.) Standard Chain: Make: DAIDO –...
  • Page 363: Special Tool

    FINAL DRIVE 11-5 Special Tool Outside Circlip Pliers: 57001-144...
  • Page 364: Drive Chain

    11-6 FINAL DRIVE Drive Chain Drive Chain Slack Inspection • Refer to the Drive Chain Slack Inspection in the Periodic Maintenance chapter. Drive Chain Slack Adjustment • Refer to the Drive Chain Slack Adjustment in the Periodic Maintenance chapter. Wheel Alignment Inspection •...
  • Page 365 FINAL DRIVE 11-7 Drive Chain • Install the link plate [A] so that the mark faces out. • Install the clip [B] so that the closed end [C] of the "U" pointed in the direction of chain rotation [D]. • Adjust the drive chain slack (see Drive Chain Slack Ad- justment in the Periodic Maintenance chapter).
  • Page 366: Sprockets

    11-8 FINAL DRIVE Sprockets Engine Sprocket Removal • Remove: Engine Sprocket Cover Bolts [A] Engine Sprocket Cover [B] Drive Chain Guide [C] • Remove the circlip [A], and take off the engine sprocket [B] together with the drive chain. ○ Using the thin blade driver [C] as shown in the figure when removal is difficult.
  • Page 367: Rear Sprocket Removal

    FINAL DRIVE 11-9 Sprockets Rear Sprocket Removal • Remove the rear wheel (see Rear Wheel Removal in the Wheels/Tires chapter). NOTICE Do not lay the wheel on the ground with the disc facing down. This can damage or warp the disc. Place blocks under the wheel so that the disc does not touch the ground.
  • Page 369 BRAKES 12-1 Brakes Table of Contents Exploded View........................12-2 Specifications ......................... 12-6 Special Tools .......................... 12-7 Brake Lever, Brake Pedal....................... 12-8 Brake Lever Play Adjustment.................... 12-8 Brake Pedal Position Adjustment..................12-8 Brake Pedal Removal ....................... 12-8 Brake Pedal Installation ....................12-8 Brake Fluid ..........................
  • Page 370: Exploded View

    12-2 BRAKES Exploded View...
  • Page 371 BRAKES 12-3 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Front Brake Reservoir Cap Screws 0.15 13 in·lb Front Master Cylinder Clamp Bolts 0.90 78 in·lb Brake Lever Pivot Bolt 0.60 52 in·lb Brake Lever Pivot Bolt Locknut 0.60 52 in·lb Brake Hose Banjo Bolts Brake Hose Clamp Mounting Bolt 0.31...
  • Page 372 12-4 BRAKES Exploded View...
  • Page 373 BRAKES 12-5 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Rear Brake Reservoir Cap Screws 0.15 13 in·lb Rear Master Cylinder Mounting Bolts 87 in·lb Brake Hose Banjo Bolts Rear Master Cylinder Push Rod Locknut Brake Pedal Bolt L, G Rear Brake Disc Mounting Bolts Caliper Bleed Valve 0.80...
  • Page 374: Specifications

    12-6 BRAKES Specifications Item Standard Service Limit Brake Lever Lever Free Play Adjustable (to suit rider) – – – Brake Fluid Grade: Front DOT3 or DOT4 – – – Rear DOT3 or DOT4 – – – Brake Pads Lining Thickness: Front 4.0 mm (0.16 in.) 1 mm (0.04 in.)
  • Page 375: Special Tools

    BRAKES 12-7 Special Tools Jack: Jack Attachment: 57001-1238 57001-1608 Attachment Jack: 57001-1252...
  • Page 376: Brake Lever, Brake Pedal

    12-8 BRAKES Brake Lever, Brake Pedal Brake Lever Play Adjustment • Refer to the Brake Lever and Pedal Adjustment in the Periodic Maintenance chapter. Brake Pedal Position Adjustment • Refer to the Brake Lever and Pedal Adjustment in the Periodic Maintenance chapter. Brake Pedal Removal •...
  • Page 377 BRAKES 12-9 Brake Lever, Brake Pedal • Replace the O-rings [A] with new ones. • Apply grease to the O-rings and shaft portion [B] of the brake pedal bolt. • Apply a non-premanent locking agent to the thread of the brake pedal bolt.
  • Page 378: Brake Fluid

    12-10 BRAKES Brake Fluid WARNING When working with the disc brake, observe the pre- cautions listed below. 1. Never reuse old brake fluid. 2. Do not use fluid from a container that has been left unsealed or that has been open for a long time. 3.
  • Page 379: Brake Line Bleeding

    BRAKES 12-11 Brake Fluid Brake Line Bleeding The brake fluid has a very low compression coefficient so that almost all the movement of the brake lever or pedal is transmitted directly to the caliper for braking action. Air, however, is easily compressed. When air enters the brake lines, brake lever or pedal movement will be partially used in compressing the air.
  • Page 380 12-12 BRAKES Brake Fluid • Bleed the brake line and the caliper as follows: ○ Repeat this operation until no more air can be seen com- ing out into the plastic hose. 1. Pump the brake lever until it becomes hard, and apply the brake and hold it [A].
  • Page 381: Caliper

    BRAKES 12-13 Caliper Caliper Removal Front Brake • Loosen the brake pad pin [A] before the caliper [B] re- moval if the caliper is to be disassembled. • Loosen the banjo bolt [C] so as not to spill brake fluid. NOTE ○...
  • Page 382: Caliper Installation

    12-14 BRAKES Caliper Caliper Installation • Install the brake pad if it was removed (see Brake Pad Installation). Front Brake • Install the caliper and tighten the bolts. Torque - Front Caliper Mounting Bolts: 25 N·m (2.5 kgf·m, 18 ft·lb) Rear Brake •...
  • Page 383: Fluid Seal Damage Inspection

    BRAKES 12-15 Caliper Fluid Seal Damage Inspection The fluid seals [A] around the piston maintains the proper pad/disc clearance. If this seal is not in good condition, pad wear will increase, and constant pad drag on the disc will raise brake and brake fluid temperature. •...
  • Page 384: Caliper Piston And Cylinder Damage

    12-16 BRAKES Caliper Caliper Piston and Cylinder Damage • Visually inspect the pistons [A] and cylinder surfaces. Replace the caliper if the cylinder and piston are badly scores or rusty. [B] Front Caliper [C] Rear Caliper Caliper Holder Shaft Wear The caliper body must slide smoothly on the caliper holder shafts [A].
  • Page 385: Brake Pad

    BRAKES 12-17 Brake Pad Brake Pad Removal Front Brake • Remove the pad pin [A]. • Take off the piston side pad [B]. • Push the caliper holder toward the piston, and then re- move another pad [C]. Rear Brake •...
  • Page 386: Brake Pad Inspection

    12-18 BRAKES Brake Pad • Tighten the brake pad pin. Torque - Brake Pad Pin: 17 N·m (1.7 kgf·m, 13 ft·lb) Rear Brake Pad Pin Plug: 2.5 N·m (0.25 kgf·m, 22 in·lb) • Check the brake for good braking power, no brake drag, and no fluid leakage.
  • Page 387: Master Cylinder

    BRAKES 12-19 Master Cylinder NOTICE Brake fluid quickly ruins painted or plastic sur- faces; any spilled fluid should be completely washed up immediately. Front Master Cylinder Removal • Remove the banjo bolt [A] to disconnect the brake hose upper end [B] from the master cylinder [C]. ○...
  • Page 388: Rear Master Cylinder Removal

    12-20 BRAKES Master Cylinder • The master cylinder clamp must be installed with the ar- row mark [A] upward. • Tighten the upper clamp bolt [B] first, and then the lower clamp bolt [C]. ○ There will be a gap at the lower mating surface of the clamp after tightening.
  • Page 389: Rear Master Cylinder Installation

    BRAKES 12-21 Master Cylinder Rear Master Cylinder Installation • Install the brake hose. ○ Replace the washers [A] are on each side of hose fitting [B] with new ones. • Tighten: Torque - Brake Hose Banjo Bolt: 25 N·m (2.5 kgf·m, 18 ft·lb) •...
  • Page 390: Master Cylinder Inspection (Visual Inspection)

    12-22 BRAKES Master Cylinder Master Cylinder Inspection (Visual Inspection) • Disassemble the front and rear master cylinders. • Check that there are no scratches, rust or pitting on the inner wall of each master cylinder [A] and on the outside of each piston [B].
  • Page 391: Brake Disk

    BRAKES 12-23 Brake Disk Brake Disc Removal • Remove the wheels (see Front/Rear Wheel Removal in the Wheels/Tires chapter). • Unscrew the mounting bolts, and take off the disc. Brake Disc Installation • Install the brake disc on the wheel so that the marked side [A] faces out.
  • Page 392: Brake Hose

    12-24 BRAKES Brake Hose Brake Hose Removal/Installation • Refer to the Brake Hose Replacement in the Periodic Maintenance chapter. Brake Hose Inspection • Refer to the Brake Hoses and Connections Inspection in the Periodic Maintenance chapter.
  • Page 393 SUSPENSION 13-1 Suspension Table of Contents Exploded View........................13-2 Specifications ......................... 13-6 Special Tools .......................... 13-8 Front Fork ..........................13-10 Air Pressure ........................13-10 Compression Damping Adjustment (Left Fork only) ............13-10 Rebound Damping Adjustment (Left Fork only)..............13-11 Spring Preload Adjustment (Right Fork only)..............13-12 Oil Change/Oil Level Adjustment ..................
  • Page 394: Exploded View

    13-2 SUSPENSION Exploded View...
  • Page 395 SUSPENSION 13-3 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Left Front Fork Cylinder Unit Front Fork Clamp Bolts (Lower) Front Fork Clamp Bolts (Upper) AL, L Left Front Fork Adjuster Assembly Locknut Left Front Fork Base Valve Assembly Left Front Fork Adjuster Assembly Pressure Relief Screws 0.13 12 in·lb...
  • Page 396 13-4 SUSPENSION Exploded View...
  • Page 397 SUSPENSION 13-5 Exploded View Torque Fastener Remarks N·m kgf·m ft·lb Rear Shock Absorber Mounting Nut (Upper) Rear Shock Absorber Mounting Nut (Lower) Tie-Rod Mounting Nuts G, R Swingarm Pivot Shaft Nut Rocker Arm Pivot Nut G, R Rear Shock Absorber Spring Locknut Gas Reservoir Damping Adjuster Assembly 29.5 Piston Rod Locknut...
  • Page 398: Specifications

    13-6 SUSPENSION Specifications Item Standard Service Limit Front Fork Air Pressure Atmospheric pressure – – – Rebound Damping Adjustment (Left 10 clicks counterclockwise (Adjustable Range) (EUR, BR) 12 clicks Fork only) 20 ±4 clicks (from the seated position adjuster counterclockwise (KX250YB) turned fully clockwise) (EUR, BR) 8 clicks counterclock- wise (KX250YC)
  • Page 399 SUSPENSION 13-7 Specifications Item Standard Service Limit Spring Preload Adjustment (Adjustable Range) 125.8 ∼ 133.8 mm (Adjusting nut position from the 129.8 mm (5.11 in.) (KX250YB) (4.95 ∼ 5.27 in.) center of the mounting hole upper) 129.5 mm (5.10 in.) (KX250YC) (EUR, BR) 131.3 mm (5.17 in.) (KX250YB) 125.8 ∼...
  • Page 400: Special Tools

    13-8 SUSPENSION Special Tools Oil Seal & Bearing Remover: Bearing Remover Shaft, 9: 57001-1058 57001-1265 Hook Wrench R37.5, R42: Bearing Remover Head, 15 × 17: 57001-1101 57001-1267 Bearing Driver Set: Hook Wrench T=3.2 R37: 57001-1129 57001-1539 Jack: Jack Attachment: 57001-1238 57001-1608 Attachment Jack: Fork Oil Seal Driver, 47:...
  • Page 401 SUSPENSION 13-9 Special Tools Fork Cylinder Holder, Hex 17: 570