YJ125S

SERVICE MANUAL

LIT-11616-17-43

5YR-28197-10

EAS00000

YJ125S 2003 SERVICE MANUAL 2003 by Yamaha Motor Taiwan Co., Ltd. First edition, November 2003 All rights reserved. Any reproduction or unauthorized use without the written permission of Yamaha Motor Taiwan Co., Ltd. is expressly prohibited. Printed in U.S.A. LIT-11616-17-43

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NOTICE
This manual was produced by the Yamaha Motor Taiwan Company, Ltd. primarily for use by Yamaha dealers and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one manual. Therefore, anyone who uses this book to perform maintenance and repairs on Yamaha vehicles should have a basic understanding of mechanics and the techniques to repair these types of vehicles. Repair and maintenance work attempted by anyone without this knowledge is likely to render the vehicle unsafe and unfit for use. Yamaha Motor Taiwan Company, Ltd. is continually striving to improve all of its models. Modifications and significant changes in specifications or procedures will be forwarded to all authorized Yamaha dealers and will appear in future editions of this manual where applicable. NOTE: Designs and specifications are subject to change without notice.

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IMPORTANT MANUAL INFORMATION
Particularly important information is distinguished in this manual by the following. The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR SAFETY IS INVOLVED!

Q w cC

The Safety Alert Symbol means ATTENTION] BECOME ALERT! YOUR SAFETY IS INVOLVED! Failure to follow WARNING instructions could result in severe injury or death to the scooter operator, a bystander or a person inspecting or repairing the scooter. A CAUTION indicates special precautions that must be taken to avoid damage to the scooter. A NOTE provides key information to make procedures easier or clearer.

HOW TO USE THIS MANUAL

This manual is intended as a handy, easy-to-read reference book for the mechanic. Comprehensive explanations of all installation, removal, disassembly, assembly, repair and check procedures are laid out with the individual steps in sequential order. 1 The manual is divided into chapters. An abbreviation and symbol in the upper right corner of each page indicate the current chapter. Refer to SYMBOLS. 2 Each chapter is divided into sections. The current section title is shown at the top of each page, except in Chapter 3 (PERIODIC CHECKS AND ADJUSTMENTS), where the sub-section title(s) appears. 3 Sub-section titles appear in smaller print than the section title. 4 To help identify parts and clarify procedure steps, there are exploded diagrams at the start of each removal and disassembly section. 5 Numbers are given in the order of the jobs in the exploded diagram. A circled number indicates a disassembly step. 6 Symbols indicate parts to be lubricated or replaced. Refer to SYMBOLS. 7 A job instruction chart accompanies the exploded diagram, providing the order of jobs, names of parts, notes in jobs, etc. 8 Jobs requiring more information (such as special tools and technical data) are described sequentially. 6 2

Limit

CHASSIS SPECIFICATIONS CHASSIS SPECIFICATIONS
Item Frame Frame type Caster angle Trail Front wheel Wheel type Rim Size Material Wheel travel Wheel runout Max. radial wheel runout Max. lateral wheel runout Rear wheel Wheel type Rim Size Material Wheel travel Wheel runout Max. radial wheel runout Max. lateral wheel runout Front tire Tire type Size Model (manufacturer) Tire pressure (cold) 0~90 kg 90~197 kg Min. tire tread depth Rear tire Tire type Size Model (manufacturer) Tire pressure (cold) 0~90 kg 90~197 kg Min. tire tread depth Standard Steel tube underbone mm Cast wheel 10 MT2.15 Aluminum 59mm Cast wheel 10 MT2.15 Aluminum 54mm Tubeless 3.50-10 51J C-922L (CHENG SHIN)
Limit 1.0 mm 1.0 mm 1.0 mm 1.0 mm 0.8mm 0.8mm
150kpa (1.5 kg/cm, 22 psi) 150kpa (1.5 kg/cm, 22 psi) Tubeless 3.50-10 51J C-6007 (CHENG SHIN) 200kpa (2.0 kg/cm, 29 psi) 225kpa (2.25 kg/cm, 32 psi)

CHASSIS SPECIFICATIONS

Item Front disc brake Brake type Operation Brake lever free play (at lever end) Recommended fluid Brake disc Diameter x thickness Min. thickness Max. deflection Brake pad lining thickness-inner Brake pad lining thickness-outer Master cylinder inside diameter Caliper cylinder inside diameter Standard Single disc brake Right-hand operation 3~5mm DOT 4 180.0 4.0 mm 6.0 mm 6.0 mm 11mm 34.93mm
Limit 180.0 3.5 mm 3.5mm 0.10 mm 0.8mm 0.8mm
Item Rear drum brake Brake type Operation Brake lever free play (at lever end) Brake drum inside diameter Lining thickness Front suspension Suspension type Front fork type Front fork travel Spring Free length Installed length Spring rate (K1) Spring stroke (K1) Spring rate (K2) Spring stroke (K2) Optional spring available Fork oil Recommended oil Quantity (each front fork leg) Inner tube outer diameter Inner tube bending limit Steering system Steering bearing type Lock to lock angle (left) Lock to lock angle (Right) Rear suspension Suspension type Rear shock absorber assembly type Rear shock absorber assembly travel Spring Free length Installed length Spring rate (K1) Spring stroke (K1) Optional spring available Standard Drum brake Left-hand operation 10~20mm 110 mm 4.0mm Telescopic Coil spring/oil damper 80 mm 257.5 mm 245.5mm 12.7N/mm (1.27 kg/mm) 0~50mm 19.6N/mm (1.96kg/mm) 50~80mm No Fork oil G10 or equivalent 126 2.5cc 33 mm Angular bearing 47.5 47.5 Swingarm Coil spring/oil damper 65mm 208mm 198mm 43N/mm (4.3kg/mm) 0~65mm No

22 12.8 1.8 4.5 1.7 23

2.2 1.25 1.2 0.7 0.7 0.7 0.7 0.7 0.7 3.0 1.0 0.8 0.15 0.7 0.8 0.7 0.7 0.8 0.7 1.0 0.8 3.2 0.7 0.7 0.7 0.7 0.2 1.0 3.1 0.7 0.4 0.4 0.8 0.45 0.15 1.2 1.0 1.2 0.7 2.3
15.8.7 5.1 5.1 5.1 5.1 5.1 5.1 21.7 7.2 5.8 1.1 5.1 5.8 5.1 5.1 5.8 5.1 7.2 5.8 23.1 5.1 5.1 5.1 5.1 1.4 7.2 22.4 5.1 2.9 2.9 5.8 3.3 1.1 8.7 7.2 8.7 5.1 16.6

And AI pipe tighten

And air shroud tighten
Part to be tightened Part name Thread Q ty size M8 M6 M6 M8 M8 M6 M6 M6 M8 M14 M36 M12 M6 M1
Tightening torque Nm mkgf ftlb 23 2.3 16.0.7 5.1.0 7.2 12.5 1.12.5 1.7 0.7 5.0.9 6.0.7 5.2.3 16.6.0 43.9.0 65.5.5 39.0.7 5.7.0 50.6
Drain bolt(engine oil ) V-belt case air filter element holder Oil pipe Cylinder stud bolt (case1) Cylinder stud bolt (case2) Crankcase cover3 Plate (V-belt guide) Idle gear plate Kick crank assembly Clutch housing Clutch carrier assembly Primary fixed sheave Starter motor assembly C.D.I. rotor Cylinder head tightening sequence
_ Screw Bolt _ _ Screw Screw Screw Bolt Nut Nut Nut Bolt Nut
CHASSIS TIGHTENING TORQUES Part to be tightened Thread size M10 M10 M10 M10 M8 M8 M8 M8 M25 M10 M10 M8 M6 M10 M5 M8 M6 M12 M14 M6 M10 M10 M8 M10 M7 Tightening torque Nm Frame and engine bracket 2 Engine bracket 2 and engine bracket 3 Engine bracket, engine and centerstand Rear shock absorber and frame Rear shock absorber and engine Rear arm Sidestand (bolt) Sidestand (nut) Steering shaft(upper nut) Handlebar holder bracket and steering shaft Handlebar holder and handlebar lower holder
Handlebar lower holder and handlebar upper holder
mkgf ftlb 4.2 5.5 3.2 3.0 1.8 2.8 0.1 1.9 7.5 6.0 4.75 3.0 0.9 2.6 0.7 2.3 1.0 7.0 10.5 1.0 2.2 3.5 2.0 2.3 0.6 30.4 39.8 23.1 21.7 13.0 20.3 0.7 13.7 54.2 SeeNOTE 43.4 34.4 21.7 6.5 18.8 5.1 16.6 7.2 50.6 75.9 7.2 15.9 25.3 14.5 16.6 4.3
Master cylinder assembly Brake hose and master cylinder Fuel sender Rear carrier Rear carrier(upper) Front wheel shaft Rear wheel shaft Rear brake camshaft lever Front brake caliper pad(bolt) Front brake caliper and front fork Front brake disc rotor Front brake hose and brake caliper Front brake caliper and bleed screw NOTE: 1. First, tighten the ring nut (lower) approximately 28 Nm (2.8mkg, 20.3ftlb) by using the torque wrench, then loosen the ring nut 1/4 turn. 2. Second, tighten the ring nut (lower) approximately 9 Nm (0.9mkg, 6.5ftlb) by using the torque wrench. 3. Installing the rubber washer. 4. Then finger tighten the center ring nut and touch rubber washer. Align the slots both ring nut and install the lock washer. 5. Final, hold the ring nuts (lower and center) and tighten the ring nut (upper) 75Nm (7.5 mkg, 54.2ftlb) by using the torque wrench. Lower ring nut Rubber washer Center ring nut Lock washer Upper ring nut

2. Check: 8 brake fluid level Below the minimum level mark a Add the recommended brake fluid to the proper level. Recommended brake fluid DOT 4
8 Use only the designated brake fluid. Other brake fluids may cause the rubber seals to deteriorate, causing leakage and poor brake performance. 8 Refill with the same type of brake fluid that is already in the system. Mixing brake fluids may result in a harmful chemical reaction, leading to poor brake performance. 8 When refilling, be careful that water does not enter the brake fluid reservoir. Water will significantly lower the boiling point of the brake fluid and could cause vapor lock.
Brake fluid may damage painted surfaces and plastic parts. Therefore, always clean up any spilt brake fluid immediately.
NOTE: In order to ensure a correct reading of the brake fluid level, make sure the top of the brake fluid reservoir is horizontal.
CHECKING THE FRONT BRAKE PADS/ CHECKING THE REAR BRAKE SHOES/ CHECKING THE FRONT BRAKE HOSE

EAS00117

CHECKING THE FRONT BRAKE PADS The following procedure applies to all of the brake pads. 1. Remove: 8 cap 1 2. Operate the brake. 3. Check: 8 front brake pad Wear indicators 2 almost touch the brake disc Replace the brake pads as a set. Refer to REPLACING THE FRONT BRAKE PADS in chapter 4.

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CHECKING THE REAR BRAKE SHOES 1. Operate the brake. 2. Check: 8 wear indicator 1 Reaches the wear limit line 2 Replace the brake shoes as a set. Refer to REAR WHEEL AND REAR BRAKE in chapter 4.

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CHECKING THE FRONT BRAKE HOSE 1. Check: 8 brake hose 1 Cracks/damage/wear Replace. 2. Check: 8 brake hose clamp Loose connection Tighten the clamp bolt. 3. Hold the scooter upright and apply the front 8 brake several times. 4. Check: 8 brake hose Brake fluid leakage Replace the damaged hose. Refer to FRONT AND REAR BRAKES in chapter 4.
CHK BRAKE FLUID CHANGE ADJ

BRAKE FLUID CHANGE

Should you feel loose when pulling Brake, it is possibly due to leaking of Brake fluid of mixing with air which led to the ineffectiveness of Brake. Since poor performance of Brake caused by mixing with air may trigger accidents, therefore inspection must be carried out prior to riding, and expel the air if necessary.

1. Place the scooter in standing position vertically on a flat floor. NOTE: 8 Use the main stand to place the scooter in upright position. 8 During change, be sure the scooter is standing vertically. 2. Remove: 8 reservoir cap 1 Remove the reservoir cap of the master cylinder at horizontal condition. 3. Bleed. 8hydraulic brake system.
***************************************************** a. Securely connect the transparent vinyl hose 1 to the fluid screw 2. b. Place the other end of the hose in the oil pan (receiving pan). c. Slowing operate the brake lever for several times. Repeat the procedures until no more brake fluid overflows from the fluid screw.
Brake fluid can cause damages to painting or plastic surfaces, so be sure to wipe clean the spilled brake fluid. d. Tighten: 8bleed screw 6Nm (0.6m kg, 4.3 ft lb)
e. Remove the reservoir diaphragm. f. Fill proper volume of designated brake fluid into the reservoir of the master cylinder. Refer to CHECKING THE BRAKE FLUID LEVEL. g. Operate brake lever slowly for several times. Repeat the procedures until the small amount of air (air bubbles) in the reservoir tank disappears, and the brake lever feels heavy. h. Bleed: Refer to BLEEDING THE HYDRAULIC BRAKE SYSTEM.
Following air expelling for the hydraulic brake, please verify the actuating condition of the brake. ***************************************************** 4. Install: 8 reservoir cap 1.6Nm (0.16m kg, 1.2 ft lb)
CHK BLEEDING THE HYDRAULIC BRAKE SYSTEM ADJ

EAS00133

BLEEDING THE HYDRAULIC BRAKE SYSTEM
Bleed the hydraulic brake system whenever: 8 the system is disassembled. 8 a brake hose is loosened, disconnected or replaced. 8 the brake fluid level is very low. 8 brake operation is faulty. 1. Remove: 8reservoir cap NOTE: 8 Be careful not to spill any brake fluid or allow the brake master cylinder reservoir to overflow. 8 When bleeding the hydraulic brake system, make sure there is always enough brake fluid before applying the brake. Ignoring this precaution could allow air to enter the hydraulic brake system, considerably lengthening the bleeding procedure. 8 If bleeding is difficult, it may be necessary to let the brake fluid settle for a few hours. Repeat the bleeding procedure when the tiny bubbles in the hose have disappeared.
2. Bleed: 8 hydraulic brake system ***************************************************** a. Fill the brake fluid reservoir to the proper level with the recommended brake fluid. b. Install the brake master cylinder reservoir diaphragm. c. Connect a clear plastic hose 1 tightly to the bleed screw 2. d. Place the other end of the hose into a container. e. Slowly apply the brake lever several times. f. Fully pull the brake lever without releasing it. g. Loosen the bleed screw. NOTE: Loosening the bleed screw will release the pressure and cause the brake lever to contact the throttle grip.

Tube wheel Tubeless wheel Tube tire only Tube or tubeless tire
8 After extensive tests, the tires listed below have been approved by Yamaha Motor Taiwan Co., Ltd. for this model. The front and rear tires should always be by the same manufacturer and of the same design. No guarantee concerning handling characteristics can be given if a tire combination other than one approved by Yamaha is used on this scooter. Front tire
Manufacturer Model CHENG SHIN C-922L Size 3.50-10 51J

Rear tire

Manufacturer Model CHENG SHIN C- 6007

Size 3.50-10 51J

New tires have a relatively low grip on the road surface until they have been slightly worn. Therefore, approximately 100 km should be traveled at normal speed before any high-speed riding is done.
NOTE: For tires with a direction of rotation mark 1: 8 Install the tire with the mark pointing in the direction of wheel rotation. 8 Align the mark 2 with the valve installation point.
CHECKING THE WHEELS/ CHECKING AND LUBRICATING THE CABLES

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CHECKING THE WHEELS The following procedure applies to both of the wheels. 1. Check: 8 wheel Damage/out-of-round Replace.
Never attempt to make any repairs to the wheel. NOTE: After a tire or wheel has been changed or replaced, always balance the wheel.

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CHECKING AND LUBRICATING THE CABLES The following procedure applies to all of the inner and outer cables.
Damaged outer cable may cause the cable to corrode and interfere with its movement. Replace damaged outer cable and inner cables as soon as possible. 1. Check: 8 outer cable Damage Replace. 2. Check: 8 cable operation Rough movement Lubricate. Recommended lubricant Engine oil or a suitable cable lubricant NOTE: Hold the cable end upright and pour a few drops of lubricant into the cable sheath or use a suitable lubricating device.
LUBRICATING THE SIDESTAND/ LUBRICATING THE CENTERSTAND

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LUBRICATING THE SIDESTAND Lubricate the pivoting point and metal-to-metal moving parts of the sidestand. Recommended lubricant Lithium-soap-based grease

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LUBRICATING THE CENTERSTAND Lubricate the pivoting point and metal-to-metal moving parts of the centerstand. Recommended lubricant Lithium-soap-based grease
CHK CHECKING AND CHARGING THE BATTERY ADJ

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ELECTRICAL SYSTEM
CHECKING AND CHARGING THE BATTERY

8 engine

MAINFOLD, AIR FILTER AND MUFFLER ASSEMBLY
31Nm(3.1m kg, 22.4 ft lb)

7Nm(0.7m kg, 5.1 ft lb)

10Nm(1.0m kg, 7.2 ft lb)
Job/Part Removing the mainfold, air filter and muffler assembly Starting motor lead / Earth lead Auto choke lead C.D.I. magneto lead / Stator lead Throttle cable Rear brake cable (adjuster / pin) Hose( from AI air filter ) Vacuum hose (from mainfold) Hose(to cylinder head ) Muffler assembly AI pipe Air filter / Breather hose Carburetor Mainfold / O-ring Joint / Gasket
Refer to LEADS, HOSES AND REAR BRAKE.
Refer to AIR INDUCTION SYSTEM in chapter 6. 1/1/1 1/1 For installation, reverse the removal procedure.

CYLINDER HEAD

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8Nm(0.8m kg, 5.8 ft lb) 8Nm(0.8m kg, 5.8 ft lb) 10Nm(1.0m kg, 7.2 ft lb)

10Nm(1.0m kg,7.2 ft lb)

12Nm(1.2m kg, 8.7 ft lb) 30Nm(3.0m kg, 21.7 ft lb)
Job/Part Removing the cylinder head Muffler assembly Air filter Mainfold Unit bolt Cooper washer Oil delivery pipe / O-ring Air shroud 1 Air shroud 2 Spark plug Breather / O-ring Engine oil cap / O-ring Valve cover / O-ring Timing chain tensioner assembly Camshaft sprocket plate Camshaft sprocket Nut / Washer Plate Cylinder head Cylinder head gasket
Remarks Remove the parts in the order listed. Refer to MAINFOLD, AIR FILTER AND MUFFLER ASSEMBLY.

1/1/1 1/1 1/4/1 1

Refer to REMOVING THE CYLINDER HEAD.

Order 17 Dowel pin

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REMOVING THE CYLINDER HEAD 1. Remove : 8 oil delivery pipe 8 engine oil cap 8 valve cover 8 Air shroud Air shroud breather
2. Align: 8 I mark a on the magneto (with the stationary pointer b on the crankcase cover)
***************************************************** a. Turn the primary sheave counterclockwise. b. When the piston is at TDC on the compression stroke, align the I mark c on the camshaft sprocket with the mark d on the cylinder head. *****************************************************
3. Loosen: 8 timing chain tensioner bolt 8 camshaft sprocket plate bolt 1 While holding the crank bolt with a wrench, remove the camshaft sprocket plate bolt 1.
4. Remove: 8 timing chain tensioner (along with the gasket) 8 camshaft sprocket plate camshaft sprocket timing chain 4
NOTE: 8 To prevent the timing chain from falling into the crankcase, fasten it with a wire. 8 While holding the C.D.I. magneto bolt with a wrench, remove the camshaft sprocket plate bolt 1.
5. Remove: 8cylinder head

NOTE: After replacing the valve guide, reface the valve seat.
Valve guide remover (4.5 mm) 90890-04116 (YM-04116) Valve guide installer (4.5 mm) 90890-04117 (YM-04117) Valve guide reamer (5.0 mm) 90890-04099 ***************************************************** 3. Eliminate: 8 carbon deposits (from the valve face and valve seat) 4. Check: 8 valve face Pitting/wear Grind the valve face. 8 valve stem end Mushroom shape or diameter larger than the body of the valve stem Replace the valve.
5. Measure: 8 valve margin thickness a Out of specification Replace the valve.
Valve margin thickness 0.85~1.15 mm(0.033~0.045 in) a 6. Measure: 8 valve stem runout Out of specification

Replace the valve.

NOTE: 8 When installing a new valve, always replace the valve guide. 8 If the valve is removed or replaced, always replace the oil seal.
Valve stem runout 0.01 mm(0.0004 in)

EAS00240

CHECKING THE VALVE SEATS The following procedure applies to all of the valves and valve seats. 1. Eliminate: 8 carbon deposits (from the valve face and valve seat) 2. Check: 8 valve seat Pitting/wear Replace the cylinder head. 3. Measure: 8 valve seat width a Out of specification der head.

Replace the cylin-

Valve seat width Intake: 0.9 ~ 1.1 mm(0.035 ~ 0.043 in) <Limit>: 1.6 mm(0.063 in) Exhaust: 0.9 ~1.1 mm(0.035~0.043 in) <Limit>: 1.6 mm(0.063 in) ***************************************************** a. Apply Mechanics blueing dye (Dykem) b onto the valve face. b. Install the valve into the cylinder head. c. Press the valve through the valve guide and onto the valve seat to make a clear impression. d. Measure the valve seat width. NOTE: Where the valve seat and valve face contacted one another, the blueing will have been removed. *****************************************************
4. Lap: 8 valve face 8 valve seat NOTE: After replacing the cylinder head or replacing the valve and valve guide, the valve seat and valve face should be lapped. *****************************************************
a. Apply a coarse lapping compound a to the valve face.
Do not let the lapping compound enter the gap between the valve stem and the valve guide. b. Apply molybdenum disulfide oil onto the valve stem. c. Install the valve into the cylinder head. d. Turn the valve until the valve face and valve seat are evenly polished, then clean off all of the lapping compound. NOTE: For the best lapping results, lightly tap the valve seat while rotating the valve back and forth between your hands. e. Apply a fine lapping compound to the valve face and repeat the above steps. f. After every lapping procedure, be sure to clean off all of the lapping compound from the valve face and valve seat. g. Apply Mechanics blueing dye (Dykem) b onto the valve face. h. Install the valve into the cylinder head. i. Press the valve through the valve guide and onto the valve seat to make a clear impression. j. Measure the valve seat width c again. If the valve seat width is out of specification, reface and lap the valve seat. *****************************************************

Piston size P 51.470 ~ 51.510 mm(2.026~ 2.028 in)
d. If out of specification, replace the piston and piston rings as a set. e. Calculate the piston-to-cylinder clearance with the following formula.
Piston-to-cylinder clearance = Cylinder bore C - Piston skirt diameter P
Piston-to-cylinder clearance 0.01 ~ 0.03 mm(0.0004~0.0012 in) <Limit>: 0.15 mm(0.006 in) f. If out of specification, replace the cylinder, and the piston and piston rings as a set. ***************************************************** 5-30

EAS00263

CHECKING THE PISTON RINGS 1. Measure: 8 piston ring side clearance Out of specification Replace the piston and piston rings as a set. NOTE: Before measuring the piston ring side clearance, eliminate any carbon deposits from the piston ring grooves and piston rings.
Piston ring side clearance Top ring 0.02 ~ 0.08 mm(0.0008~0.0031 in) <Limit>: 0.13mm(0.0051 in) 2nd ring 0.02 ~ 0.06 mm(0.0008~0.0024 in) <Limit>:0.12 mm(0.0047 in)
2. Install: 8 piston ring (into the cylinder)
NOTE: Level the piston ring into the cylinder with the piston crown. a 20 mm (0.79 in) 3. Measure: 8 piston ring end gap Out of specification ton ring.

Replace the pis-

NOTE: The oil ring expander spacers end gap cannot be measured. If the oil ring rails gap is excessive, replace all three piston rings.
Piston ring end gap Top ring 0.10 ~ 0.20 mm (0.004 ~ 0.008 in) <Limit>: 0.45 mm (0.018 in) 2nd ring 0.20 ~ 0.30 mm (0.008 ~ 0.012 in) <Limit>: 0.65 mm (0.026 in) Oil ring 0.06 ~ 0.15 mm (0.002 ~ 0.006 in)

EAS00265

CHECKING THE PISTON PIN 1. Check: 8 piston pin Blue discoloration/grooves Replace the piston pin and then check the lubrication system.
2. Measure: 8 piston pin outside diameter a Out of specification Replace the piston pin. Piston pin outside diameter 12.996 ~ 13.000 mm (0.5117~0.5118 in) <Limit>:12.976 mm (0.5109 in) 3. Measure: 8 piston pin bore diameter b Out of specification Replace the piston. b Piston pin bore diameter 13.002 ~ 13.013 mm (0.5119 ~ 0.5123 in) <Limit>:13.043 mm (0.5135 in) 4. Calculate: 8 piston-pin-to-piston-pin-bore clearance Out of specification Replace the piston pin and piston as a set.
Piston-pin-to-piston-pin-bore clearance = Piston pin bore diameter b Piston pin outside diameter a
Piston-pin-to-piston clearance <Limit>:0.067 mm(0.0026 in)
CHECKING THE TIMING CHAIN GUIDE 1. Check: 8 timing chain guide (exhaust side) Damage/wear Replace

EAS00267

INSTALLING THE PISTON AND CYLINDER 1. Install: 8 oil ring expander oil ring rail 2nd ring top ring 4 NOTE: Be sure to install the piston rings so that the manufacturers marks or numbers face up.

Disconnect the C.D.I. magneto lead coupler. For installation, reverse the removal procedure.
REMOVING THE C.D.I. MAGNETO 1. Remove: 8 nut plate washer
NOTE: 8 While holding the C.D.I. magneto rotor with the holding tool 2, loosen the C.D.I. magneto nut1. 8 Do not allow the sheave holder to touch the projection on the C.D.I. magneto rotor.
Rotor holding tool 90890-01235 (YU-01235)
2. Remove: 8 C.D.I. magneto rotor(with flywheel puller 2 ) Flywheel puller 90890-01189 (YM-01189)
INSTALLING THE C.D.I. MAGNETO 1. Install: 8 C.D.I. magneto rotor 1 NOTE: 8 Clean the tapered portion of the crankshaft and the magneto rotor hub. 8 When installing the magneto rotor, make sure the woodruff key is properly seated in the keyway of the crankshaft. 2. Tighten: 8 nut Nm (7.0 m kg, 50.6 ft lb) NOTE: 8 While holding the C.D.I. magneto with the holding tool 3, tighten the C.D.I. magneto rotor nut 2. 8 Do not allow the sheave holder to touch the projection on the C.D.I. magneto rotor.

OIL PUMP

EAS00360
7Nm(0.7m kg, 5.1 ft lb) 7Nm(0.7m kg, 5.1 ft lb)
Job/Part Disassembling the oil pump C.D.I. magneto Cover O-ring Gasket Oil seal Dowel pin Circlip / Plate washer Oil pump driven gear Dowel pin Oil pump body Outer rotor Inner rotor Oil pump shaft Oil pump housing cover Gasket
Remarks Remove the parts in the order listed. Refer to C.D.I. MAGNETO
1 1/1 For assembly, reverse the disassembly procedure.

EAS00364

CHECKING THE OIL PUMP 1. Check: 8 oil pump driven gear 1 Cracks/damage/wear Replace the defective part(s).
2. Measure: 8 inner-rotor-to-outer-rotor-tip clearance a 8 outer-rotor-to-oil-pump-housing clearance b 8 oil-pump-housing-to-inner-rotor-andouter-rotor clearance c Out of specification Replace the oil pump. 1 Inner rotor 2 Outer rotor 3 Oil pump housing

3 b c 1

Inner-rotor-to-outer-rotor-tip clearance 0.15 mm (0.006 in) <Limit>: 0.23 mm (0.009 in) Outer-rotor-to-oil-pump-housing clearance 0.013 ~ 0.036 mm (0.0005~0.0014 in) <Limit>: 0.106 mm (0.0042 in) Oil-pump-housing-to-inner-rotorand-outer-rotor clearance 0.06 ~ 0.10 mm (0.002~0.004 in) <Limit>: 0.17 mm (0.0067 in)
3. Check: 8 oil pump operation Rough movement Repeat steps (1) and (2) or replace the defective part(s).

EAS00376

INSTALLING THE OIL PUMP 1. Install: 8 gasket 1 New 8 oil pump assemblyoil pump bolt 7 Nm (0.7 m kg, 5.1 ft lb)
After tightening the bolts, make sure the oil pump turns smoothly.

TRANSMISSION

EAS00419
12Nm(1.2m kg, 8.7 ft lb) B
Job/Part Removing the transmission, shift drum assembly, and shift forks Transmission oil Rear wheel Crankcase cover Belt drive Secondary sheave Crankcase cover- 2 Crankcase cover gasket- 2 Dowel pin Primary drive gear shaft Plate washer Main axle Drive axle

4. Install: 8 crankshaft crankcase (right ) 5. Tighten: 8 crankcase 12 Nm (1.2 m kg, 8.7 ft lb)
CHAPTER 6 CARBRETOR CARBURETOR.... 6-1 CHECKING THE CARBURETOR... 6-3 ASSEMBLING THE CARBURETOR.. 6-5 INSTALLING THE CARBURETOR... 6-6 MEASURING AND ADJUSTING THE FUEL LEVEL.. 6-7 CHECKING THE FUEL COCK... 6-8 CHECKING THE AUTOCHOKE UNIT... 6-8 AIR INDUCTION SYSTEM... 6-10 CHECKING THE AIR INDUCTION SYSTEM.. 6-11

CARBURETOR CARBURETOR

EAS00483

CARBURETOR

p a o y w q e u t r 8

Order q w e r t y u i o

Job/Part Disassembling the carburetor Auto choke unit Auto choke holder Throttle stop screw / Spring Bracket Clamp Vacuum chamber cover / Piston valve spring Piston valve Jet needle kit Float chamber Gasket Accelerator pump assembly Float pin Float Needle valve Needle valve seat Main jet Main nozzle Main air jet Pilot jet

Qty 1/1 1/1 1

Order p a
Job/Part Carburetor heater Ground terminal

EAS00485

CHECKING THE CARBURETOR 1. Check: 8 carburetor body 8 float chamber Cracks/damage Replace. 2. Check: 8 fuel passages Obstruction Clean. ***************************************************** a. Wash the carburetor in a petroleum-based solvent. Do not use any caustic carburetor cleaning solution. b. Blow out all of the passages and jets with compressed air. *****************************************************
3. Check: 8 float chamber body 1 Dirt Clean. 4. Check: 8 float chamber rubber gasket 2 Cracks/damage/wear Replace.

5. Check: 8 float Damage

6. Check: 8 needle valve needle valve seat 2 Damage/obstruction/wear Replace the needle valve, needle valve seat and Oring as a set. 7. Check: 8 O-ring 3 Damage/wear Replace the needle valve, needle valve seat and O-ring as a set. 8. Check: 8 piston valve 1 Damage/scratches/wear Replace. 8 piston valve diaphragm 2 Cracks/tears Replace.
9. Check: 8 vacuum chamber cover piston valve spring 2 Cracks/damage Replace.
10. Check: 8jet needle1 8main jet2 8main nozzle3 8pilot jet4 8main air jet5 Bends/damage/wear Replace. Obstruction Clean. Blow out the jets with compressed air.
11. Check: 8 piston valve movement Insert the piston valve into the carburetor body and move it up and down. Tightness Replace the piston valve. 12. Check: 8 vacuum hoses 8 fuel hoses Cracks/damage/wear Replace. Obstruction Clean. Blow out the hoses with compressed air. 6-4

EAS00487

ASSEMBLING THE CARBURETOR
8 Before assembling the carburetor, wash all of the parts in a petroleum-based solvent. 8 Always use a new gasket.
1. Install: 8 main nozzle main jet pilot jet 3
2. Install: 8 needle valve seat float needle valve float pin screw 5
3. Install: 8 accelerator pump assembly
4. Install: 8piston valve 8jet needle 8piston valve spring 8vacuum chamber cover

EAS00492

AIR INDUCTION SYSTEM

EAS00510
CHECKING THE AIR INDUCTION SYSTEM 1. Check: 8 hoses Loose connection Connect properly. Cracks/damage Replace. 8 pipe Cracks/damage Replace.
2. Check: 8 air cut-off valve Cracks/damage
NOTE: When the negative pressure is applied to the part 1, check that the continuity in the direction of arrow mark is completely lost. If the negative pressure is not loaded, the continuity can be obtained.

CHAPTER 7 ELECTRICAL

ELECTRICAL COMPONENTS... 7-1 WIRING DIAGRAM... 7-2 CHECKING SWITCH CONTINUITY... 7-4 CHECKING THE SWITCHES.. 7-5 CHECKING THE BULBS AND BULB SOCKETS.. 7-6 TYPES OF BULBS... 7-6 CHECKING THE CONDITION OF THE BULBS. 7-7 CHECKING THE CONDITION OF THE BULB SOCKETS. 7-8 IGNITION SYSTEM... 7-9 CIRCUIT DIAGRAM... 7-9 TROUBLESHOOTING... 7-10 ELECTRIC STARTING SYSTEM... 7-14 CIRCUIT DIAGRAM... 7-14 STARTING CIRCUIT CUT-OFF SYSTEM OPERATION. 7-15 TROUBLESHOOTING... 7-16 STARTER MOTOR... 7-20 CHECKING THE STARTER MOTOR... 7-21 ASSEMBLING THE STARTER MOTOR... 7-23 CHARGING SYSTEM.... 7-24 CIRCUIT DIAGRAM... 7-24 TROUBLESHOOTING... 7-25 LIGHTING SYSTEM... 7-27 CIRCUIT DIAGRAM... 7-27 TROUBLESHOOTING... 7-28 CHECKING THE LIGHTING SYSTEM.. 7-29 SIGNALING SYSTEM... 7-33 CIRCUIT DIAGRAM... 7-33 TROUBLESHOOTING... 7-34 CHECKING THE SIGNALING SYSTEM... 7-35 CRABURETOR HEATING SYSTEM... 7-41 CIRCUIT DIAGRAM... 7-41 TROUBLESHOOTING... 7-42 AUTO CHOKE SYSTEM.. 7-45 CIRCUIT DIAGRAM... 7-45 TROUBLESHOOTING... 7-46

ELECTRICAL COMPONENTS

EAS00729

ELECTRICAL

Wire harness Battery C.D.I. unit Carburetor heater Sidestand switch Horn Rectifier/Regulator Ignition coil Rear brake light switch Main switch q w e r t y Thermo switch Fuel sender Starter relay Turn signal relay Front brake light switch Starting circuit cut-off relay
WR WL BR BR GW Or R W WR WR WL WL B B YR W Or GW WL WR

MAIN LOCK OFF ON

GW BR Or Or

R B Br B (BLACK)

1 q w 3

W YR BW

W B R YR (BLUE)

B BW Sb LY

WIRING DIAGRAM
E/G STOP OFF RUN BW BW LW Br BW BW Br LW

B B (BLACK)

START OFF START

B (BLACK)

DIMMER SW B

TURN SIGNAL SW L N R Br

(BLACK)

OFF PUSH HI LO

Dg L B B

(BLACK) (BLACK)

B Y G B Y B G Ch Dg
(BLACK) L Ch P BrW B Dg Y B (BLACK)

BrW Dg

Ch L P B

12V 60W/55W

TURN 12V3W

12V 10W

L B B (BROWN)

Ch Dg GY

12V 27/8W

L Y B (GREEN)

2 L/W R/W Starter relay 1

EAS00750

8. Engine stop switch 8 Check the engine stop switch for continuity. Refer to CHECKING THE SWITCHES. 8 Is the engine stop switch OK? YES NO Replace the right handlebar switch.

EAS00752

8 Does the starter relay have continuity between red3 and red 4? YES NO Replace the starter relay.
9. Sidestand switch 8 Check the sidestand switch for continuity. Refer to CHECKING THE SWITCHES. 8 Is the sidestand switch OK? YES NO Replace the sidestand switch.
6. Main switch 8Check the main switch for continuity. Refer to CHECKING THE SWITCHES. 8Is the main switch OK? YES NO

EAS00764

Replace the main switch.
10.Start switch 8 Check the start switch for continuity. Refer to CHECKING THE SWITCHES. 8 Is the start switch OK? YES NO Replace the right handlebar switch.

EAS00766

11. Wiring 8 Check the entire starting systems wiring. Refer to CIRCUIT DIAGRAM. 8 Is the starting systems wiring properly connected and without defects? YES The starting system circuit is OK. NO Properly connect or repair the starting systems wiring or replace the C.D.I. unit.

STARTER MOTOR

3.5Nm(0.35m kg, 2.5 ft lb)
Job/Part Starter motor removal Air filter case
Remarks Remove the parts in the order listed. Refer toLEADS, HOSES AND REAR BRAKE in chapter 5.
Starter motor lead Starter motor
For installation, reverse the removal procedure. Remove the parts in the order listed. 1 For assembly, reverse the disassembly procedure.
Starter motor disassembly O-ring Rear bracket Gasket Stator assembly Armature coil Circlip Brush Brush spring Brush seat Plate washer Front bracket

EAS00769

CHECKING THE STARTER MOTOR 1. Check: 8 commutator Dirt Clean with 600-grit sandpaper. 2. Measure: 8 commutator diameter a Out of specification Replace the starter motor. Commutator wear limit 21 mm (0.83 in) 3. Measure: 8 mica undercut a Out of specification Scrape the mica to the proper measurement with a hacksaw blade that has been grounded to fit the commutator. Mica undercut 1.5 mm (0.06 in) NOTE: The mica of the commutator must be undercut to ensure proper operation of the commutator.
4. Measure: 8 armature assembly resistances (commutator and insulation) Out of specification Replace the starter motor. ***************************************************** a. Measure the armature assembly resistances with the pocket tester. Pocket tester 90890-03132 (YU-03112-C)
Armature coil Commutator resistance 1 0.0306 ~ 0.0374 at 20C Insulation resistance 2 Above 1 M at 20C b. If any resistance is out of specification, replace the starter motor. 7-21 *****************************************************