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FOREWORD

INTRODUCTION

Congratulations on your purchase of 
a Yamaha YZ series. This model is 
the culmination of Yamaha's vast ex-
perience in the production of paceset-
ting racing machines. It represents 
the highest grade of craftsmanship 
and reliability that have made Yama-
ha a leader.
This manual explains operation, in-
spection, basic maintenance and tun-
ing of your machine. If you have any 
questions about this manual or your 
machine, please contact your Yama-
ha dealer.

Yamaha continually seeks advance-
ments in product design and quality. 
Therefore, while this manual contains 
the most current product information 
available at the time of printing, there 
may be minor discrepancies between 
your machine and this manual. If you 
have any questions concerning this 
manual, please consult your Yamaha 
dealer.

PLEASE READ THIS MANUAL 
CAREFULLY AND COMPLETELY 
BEFORE OPERATING THIS MA-
CHINE. DO NOT ATTEMPT TO OP-
ERATE THIS MACHINE UNTIL YOU 
HAVE ATTAINED A SATISFACTO-
RY KNOWLEDGE OF ITS CON-
TROLS AND OPERATING 
FEATURES AND UNTIL YOU HAVE 
BEEN TRAINED IN SAFE AND 
PROPER RIDING TECHNIQUES. 
REGULAR INSPECTIONS AND 
CAREFUL MAINTENANCE, 
ALONG WITH GOOD RIDING 
SKILLS, WILL ENSURE THAT YOU 
SAFETY ENJOY THE CAPABILI-
TIES AND THE RELIABILITY OF 
THIS MACHINE.

PARTICULARLY IMPORTANT 
INFORMATION

The Safety Alert Symbol means AT-
TENTION! BECOME ALERT! YOUR 
SAFETY IS INVOLVED!

Failure to follow WARNING instruc-
tions could result in severe injury or 
death to the machine operator, a by-
stander, or a person inspecting or re-
pairing the machine.

A CAUTION indicates special pre-
cautions that must be taken to avoid 
damage to the machine.

A NOTE provides key information to 
make procedures easier or clearer.

IMPORTANT NOTICE

THIS MACHINE IS DESIGNED 
STRICTLY FOR COMPETITION 
USE, ONLY ON A CLOSED 
COURSE.  It is illegal for this machine 
to be operated on any public street, 
road, or highway. Off-road use on 
public lands may be illegal. Please 
check local regulations before riding.

1. THIS MACHINE IS TO BE OP-

ERATED BY AN EXPERI-
ENCED RIDER ONLY.
Do not attempt to operate this 
machine at maximum power 
until you are totally familiar 
with its characteristics.

2. THIS MACHINE IS DESIGNED 

TO BE RIDDEN BY THE OP-
ERATOR ONLY.
Do not carry passengers on 
this machine.

3. ALWAYS WEAR PROTEC-

TIVE APPAREL.
When operating this ma-
chine, always wear an ap-
proved helmet with goggles 
or a face shield. Also wear 
heavy boots, gloves, and pro-
tective clothing. Always wear 
proper fitting clothing that 
will not be caught in any of 
the moving parts or controls 
of the machine.

4. ALWAYS MAINTAIN YOUR 

MACHINE IN PROPER 
WORKING ORDER.
For safety and reliability, the 
machine must be properly 
maintained. Always perform 
the pre-operation checks in-
dicated in this manual. Cor-
recting a mechanical problem 
before you ride may prevent 
an accident.

5. GASOLINE IS HIGHLY FLAM-

MABLE.
Always turn off the engine 
while refueling. Take care to 
not spill any gasoline on the 
engine or exhaust system. 
Never refuel in the vicinity of 
an open flame, or while 
smoking.

6. GASOLINE CAN CAUSE IN-

JURY.
If you should swallow some 
gasoline, inhale excess gaso-
line vapors, or allow any gas-
oline to get into your eyes, 
contact a doctor immediately. 
If any gasoline spills onto 
your skin or clothing, imme-
diately wash skin areas with 
soap and water, and change 
your clothes.

7. ONLY OPERATE THE MA-

CHINE IN AN AREA WITH AD-
EQUATE VENTILATION.
Never start the engine or let it 
run for any length of time in 
an enclosed area. Exhaust 
fumes are poisonous. These 
fumes contain carbon mon-
oxide, which by itself is odor-
less and colorless. Carbon 
monoxide is a dangerous gas 
which can cause uncon-
sciousness or can be lethal.

8. PARK THE MACHINE CARE-

FULLY; TURN OFF THE EN-
GINE.
Always turn off the engine if 
you are going to leave the 
machine. Do not park the ma-
chine on a slope or soft 
ground as it may fall over.

9. PROPERLY SECURE THE 

MACHINE BEFORE TRANS-
PORTING IT.
When transporting the ma-
chine in another vehicle, al-
ways be sure it is properly 
secured and in an upright po-
sition and that the fuel cock is 
in the "OFF" position. Other-
wise, fuel may leak out of the 
carburetor or fuel tank.

Summary of Contents for YZ125 2008

Page 1: ...00 SHINGAI IWATA SHIZUOKA JAPAN PRINTED ON RECYCLED PAPER OWNER S SERVICE MANUAL MANUEL D ATELIER DU PROPRIETAIRE FAHRER UND WARTUNGSHANDBUCH MANUALE DI SERVIZIO DEL PROPRIETARIO YZ125 X X1 1C3 28199 33 2008 YZ125 X X1 2008 1C3 9 33_cover 07 6 14 9 59 AM Page 1 ...

Page 2: ...1C3 9 33_cover 07 6 14 9 59 AM Page 2 ...

Page 3: ...YZ125 X X1 1C3 28199 33 E0 2008 OWNER S SERVICE MANUAL ...

Page 4: ......

Page 5: ... S SERVICE MANUAL 2007 by Yamaha Motor Co Ltd 1st Edition June 2007 All rights reserved Any reprinting or unauthorized use without the written permission of Yamaha Motor Co Ltd is expressly prohibited Printed in Japan ...

Page 6: ...iding 1 THIS MACHINE IS TO BE OP ERATED BY AN EXPERI ENCED RIDER ONLY Do not attempt to operate this machine at maximum power until you are totally familiar with its characteristics 2 THIS MACHINE IS DESIGNED TO BE RIDDEN BY THE OP ERATOR ONLY Do not carry passengers on this machine 3 ALWAYS WEAR PROTEC TIVE APPAREL When operating this ma chine always wear an ap proved helmet with goggles or a fac...

Page 7: ...b for the class 500 cc minimum 102 kg 225 lb In modifying your machine e g for weight reduction take note of the above limits of weight HOW TO USE THIS MANUAL FINDING THE REQUIRED PAGE 1 This manual consists of seven chapters General Information Specifications Regular inspec tion and adjustments Engine Chassis Electrical and Tun ing 2 The table of contents is at the be ginning of the manual Look o...

Page 8: ...step by step format sup plements 5 are given in addition to the exploded diagram and job instruction chart ILLUSTRATED SYMBOLS Refer to the illustration Illustrated symbols 1 to 7 are used to identify the specifications appear ing in the text 1 With engine mounted 2 Filling fluid 3 Lubricant 4 Special tool 5 Tightening 6 Specified value Service limit 7 Resistance Ω Voltage V Electric current A Ill...

Page 9: ...TABLE OF CONTENTS GENERAL INFORMATION 1 SPECIFICATIONS 2 REGULAR INSPECTION AND ADJUSTMENTS 3 ENGINE 4 CHASSIS 5 ELECTRICAL 6 TUNING 7 ...

Page 10: ...AND MAINTE NANCE 3 3 ENGINE 3 5 CHASSIS 3 8 ELECTRICAL 3 18 CHAPTER 4 ENGINE SEAT FUEL TANK AND SIDE COVERS 4 1 EXHAUST PIPE AND SI LENCER 4 3 RADIATOR 4 5 CARBURETOR AND REED VALVE 4 7 CYLINDER HEAD CYLIN DER AND PISTON 4 12 CLUTCH 4 19 KICK SHAFT AND SHIFT SHAFT 4 23 YPVS GOVERNOR 4 28 WATER PUMP 4 30 CDI MAGNETO 4 33 ENGINE REMOVAL 4 35 CRANKCASE AND CRANK SHAFT 4 39 TRANSMISSION SHIFT CAM AND ...

Page 11: ...e subject to change without notice 1 Clutch lever 2 Engine stop switch 3 Front brake lever 4 Throttle grip 5 Radiator cap 6 Fuel tank cap 7 Kickstarter crank 8 Fuel tank 9 Radiator 10 Coolant drain bolt 11 Check bolt Transmission oil level 12 Rear brake pedal 13 Valve joint 14 Fuel cock 15 Air filter 16 Drive chain 17 Shift pedal 18 Starter knob 19 Front fork 1 ...

Page 12: ...k breather hose In this installation make sure the arrow faces the fuel tank and also downward COLLAR tool for YPVS This collar 1 is used to remove and install the push rod of the engine NIPPLE WRENCH This nipple wrench 1 is used to tighten the spoke IMPORTANT INFORMATION PREPARATION FOR REMOVAL AND DISASSEMBLY 1 Remove all dirt mud dust and foreign material before removal and disassembly When was...

Page 13: ...arings liberally when installing Do not use compressed air to spin the bearings dry This causes dam age to the bearing surfaces CIRCLIPS 1 All circlips should be inspected carefully before reassembly Al ways replace piston pin clips after one use Replace distorted cir clips When installing a circlip 1 make sure that the sharp edged corner 2 is positioned opposite to the thrust 3 it receives See th...

Page 14: ...ation Crankcase separating tool YU 1135 A 90890 01135 These tool is used to remove the crankshaft from either case Flywheel puller YM 1189 90890 01189 This tool is used to remove the fly wheel magneto Rotor holding tool YU 1235 90890 01235 This tool is used when loosening or tightening the flywheel magneto se curing nut Dial gauge and stand YU 3097 90890 01252 Stand YU 1256 These tools are used to...

Page 15: ...ols are used for checking the cooling system Flywheel puller YU 33270 B 90890 01362 These tool is used to split the crank case Steering nut wrench YU 33975 90890 01403 This tool is used when tighten the steering ring nut to specification Cap bolt wrench YM 01500 90890 01500 This tool is used to loosen or tighten the base valve Cap bolt ring wrench YM 01501 90890 01501 This tool is used to loosen o...

Page 16: ...tch holding tool YM 91042 90890 04086 This tool is used to hold the clutch when removing or installing the clutch boss securing nut Dynamic spark tester YM 34487 Ignition checker 90890 06754 This instrument is necessary for checking the ignition system compo nents YAMAHA Bond No 1215 ThreeB ond No 1215 90890 85505 This sealant Bond is used for crankcase mating surface etc Tool name Part number How...

Page 17: ...to activate the front brake REAR BRAKE PEDAL The rear brake pedal 1 is located on the right side of the machine Press down on the brake pedal to activate the rear brake FUEL COCK The fuel cock supplies fuel from the tank to carburetor and also filters the fuel The fuel cock has the two posi tions OFF With the lever in this position fuel will not flow Always return the lever to this position when t...

Page 18: ... spark plug condi tion it will show a rich condition during break in 5 Allow the engine to cool Restart the engine and operate the ma chine as in the step above for five minutes Then very briefly shift to the higher gears and check full throttle response Stop and check the spark plug 6 After again allowing the engine to cool restart and run the machine for five more minutes Full throttle and the h...

Page 19: ...ower bracket Rear For link type Assembly of links Link to frame Link to rear shock absorber Link to swingarm Installation of rear shock absorber Rear shock absorber to frame Installation of swingarm Tightening of pivot shaft Wheel Installation of wheel Front Tightening of wheel axle Tightening of axle holder Rear Tightening of wheel axle Wheel to rear wheel sprocket Brake Front Brake caliper to fr...

Page 20: ...ain with a paper towel and lubri cate the chain to prevent rust 7 Clean the seat with a vinyl uphol stery cleaner to keep the cover pliable and glossy 8 Automotive wax may be applied to all painted or chromed surfac es Avoid combination cleaner waxes as they may contain abra sives 9 After completing the above start the engine and allow it to idle for several minutes STORAGE If your machine is to b...

Page 21: ... stroke 54 54 5 mm 2 126 2 146 in Compression ratio 8 6 10 7 1 Starting system Kick starter Lubrication system Premix 30 1 Yamalube 2 R Oil type or grade 2 stroke Transmission oil Yamalube 4 10W 30 or SAE 10W 30 type SE motor oil Periodic oil change 0 66 L 0 58 Imp qt 0 69 US qt Total amount 0 70 L 0 62 Imp qt 0 74 US qt Coolant capacity including all routes 0 9 L 0 79 Imp qt 0 95 US qt Air filter...

Page 22: ...si Brake Front brake type Single disc brake Operation Right hand operation Rear brake type Single disc brake Operation Right foot operation Suspension Front suspension Telescopic fork Rear suspension Swingarm link type monocross suspension Shock absorber Front shock absorber Coil spring oil damper Rear shock absorber Coil spring gas oil damper Wheel travel Front wheel travel 300 mm 11 8 in Rear wh...

Page 23: ...ch Plain B 1 0 mm 0 039 in T 2 35 mm 0 093 in End gap installed 0 5 0 7 mm 0 020 0 028 in 1 2 mm 0 047 in Side clearance installed 0 035 0 070 mm 0 0014 0 0028 in 0 1 mm 0 004 in Crankshaft Crank width A 55 90 55 95 mm 2 201 2 203 in Runout limit C 0 03 mm 0 0012 in 0 05 mm 0 0020 in Connecting rod big end side clearance D 0 06 0 64 mm 0 002 0 025 in Small end free play F 0 8 1 0 mm 0 031 0 039 in...

Page 24: ...rade oiled filter Foam air filter oil or equivalent oil Carburetor USA CDN EUROPE AUS NZ ZA Type Manufacturer TMXχ38SS MIKUNI I D mark 1C35 30 1C36 40 1C37 50 Main jet M J 410 430 Jet needle clip position J N 6BFY42 74 3 6BFY43 74 3 Cutaway C A 4 0 Pilot jet P J 40 45 40 Pilot air screw P A S 2 1 4 Valve seat size V S ø3 8 mm 0 15 in Starter jet G S 80 Fuel level F L 9 5 10 5 mm 0 37 0 41 in Reed ...

Page 25: ...48 mm 1 89 in Front fork top end 5 mm 0 2 in Rear suspension USA CDN ZA AUS NZ EUROPE Shock absorber travel 131 5 mm 5 18 in Spring free length Approx 265 mm 10 43 in Fitting length One I D mark 258 mm 10 16 in 252 mm 9 92 in Two I D marks 264 mm 10 39 in 258 mm 10 16 in Three I D marks 255 5 mm 10 06 in 249 5 mm 9 82 in Min Max One I D mark 245 5 263 5 mm 9 67 10 37 in Two I D marks 251 5 269 5 m...

Page 26: ... mm 0 375 in Caliper cylinder inside dia 22 65 mm 0 892 in 2 Brake fluid type DOT 4 Rear disc brake Disc outside dia Thickness 245 4 0 mm 9 65 0 16 in 245 3 5 mm 9 65 0 14 in Deflection limit 0 15 mm 0 006 in Pad thickness 6 4 mm 0 25 in 1 0 mm 0 04 in Master cylinder inside dia 11 0 mm 0 433 in Caliper cylinder inside dia 25 4 mm 1 000 in 1 Brake fluid type DOT 4 Brake lever and brake pedal Brake...

Page 27: ...ightening torque Nm m kg ft lb Spark plug M14S 1 25 1 20 2 0 14 Cylinder head nut M8 1 25 5 28 2 8 20 Cylinder head stud M8 1 25 5 13 1 3 9 4 Cylinder nut M8 1 25 4 30 3 0 22 Cylinder stud M10 1 25 4 13 1 3 9 4 Power valve Cover M5 0 8 4 5 0 5 3 6 Link lever M4 0 7 1 4 0 4 2 9 Holder power valve M5 0 8 4 8 0 8 5 8 Push rod M5 0 8 1 5 0 5 3 6 Thrust plate M5 0 8 1 4 0 4 2 9 Governor fork M4 0 7 2 5...

Page 28: ...Thank you very much for your reading Please click here and go back to the website Then you can download the complete manual instantly No waiting ...

Page 29: ...Bearing plate cover shift cam M6 1 0 2 10 1 0 7 2 Shift guide M6 1 0 2 10 1 0 7 2 Stopper lever M6 1 0 1 10 1 0 7 2 Segment M8 1 25 1 30 3 0 22 Exhaust pipe M6 1 0 2 12 1 2 8 7 Exhaust pipe stay front M6 1 0 1 12 1 2 8 7 Exhaust pipe stay rear M6 1 0 1 12 1 2 8 7 Silencer Silencer and frame M6 1 0 2 12 1 2 8 7 Fiber Except for EUROPE M6 1 0 2 10 1 0 7 2 Fiber For EUROPE M6 1 0 4 10 1 0 7 2 Part to...

Page 30: ...6 4 3 Front wheel axle and axle nut M16 1 5 1 105 10 5 75 Front wheel axle holder M8 1 25 4 21 2 1 15 Front brake disc and wheel hub M6 1 0 6 12 1 2 8 7 Rear brake disc and wheel hub M6 1 0 6 14 1 4 10 Footrest bracket and frame M10 1 25 4 55 5 5 40 Brake pedal mounting M8 1 25 1 26 2 6 19 Rear brake master cylinder and frame M6 1 0 2 10 1 0 7 2 Rear brake master cylinder cap M4 0 7 2 2 0 2 1 4 Re...

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