Yamaha SR125 98 Manual

FOREWORD
This Supplementary Service Manual has been prepared to introduce new service and data for the
SR125’98.Forcompleteinformationonserviceprocedures,itisnecessarytousethisSupplementary
Service Manual together with following manual:
SR125 ’97 SERVICE MANUAL: 3MW-AE1
SR125 ’98
SUPPLEMENTARY
SERVICE MANUAL
1997 by Yamaha Motor Co., Ltd.
1st Edition July 1997
All rights reserved. Any reprinting or
unauthorized use without the written
permission of Yamaha Motor Co., Ltd.
is expressly prohibited.

NOTE:
CAUTION:
EB001000 NOTICE
This manual was produced by the Yamaha Motor Company 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,
so it is assumed that anyone who uses this book to perform maintenance and repairs on Yamaha mo-
torcycleshas abasic understandingof themechanical ideasand theprocedures ofmotorcycle repair.
Repairs attempted by anyone without this knowledge are likely to render the motorcycle unsafe and
unfit for use.
YamahaMotorCompany,Ltd.iscontinuallystrivingtoimproveallitsmodels.Modificationsandsignifi-
cant changes in specifications or procedures will be forwarded to all authorized Yamaha dealers and
will appear in future editions of this manual where applicable.
Designs and specifications are subject to change without notice.
IMPORTANT INFORMATION
Particularly important information is distinguished in this manual by the following notations.
The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR
SAFETY IS INVOLVED!
FailuretofollowWARNINGinstructionscouldresultinsevereinjuryor deathto
the motorcycle operator, a bystander or a person inspecting or repairing the
motorcycle.
ACAUTION indicatesspecial precautionsthatmustbetaken toavoid damage
to the motorcycle.
NOTE: A NOTE provides key information to make procedures easier or clearer.

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2
6
7
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43
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HOW TO USE THIS MANUAL
CONSTRUCTION OF THIS MANUAL
This manual consists of chapters for the main categories of subjects. (See “Illustrated symbols”)
1st title 1: This is a chapter with its symbol on the upper right of each page.
2nd title 2: This title appears on the upper of each page on the left of the chapter symbol.
(For the chapter “Periodic inspection and adjustment” the 3rd title appears.)
3rd title 3: This is a final title.
MANUAL FORMAT
Alloftheproceduresinthismanualareorganizedinasequential,step-by-stepformat.Theinformation
has been compiled to provide the mechanic with an easy to read, handy reference that contains com-
prehensive explanations of all disassembly, repair, assemblyand inspections. A set of particularlyim-
portant procedure ( 4) is placed between aline of asterisks (*); with each procedure preceded by ().
IMPORTANT FEATURES
Data and a special tool are framed in a box preceded by a relevant symbol (5).
Anencirclednumeral( 6)indicatesapartname,andanencircledalphabeticalletterdataoranalign-
ment mark (7), the others being indicated by an alphabetical letter in a box (8).
A condition of a faulty component will precede an arrow symbol and course of action required the
symbol ( 9).
EXPLODED DIAGRAM
Eachchapterprovidesexplodeddiagramsbeforeeachdisassemblysectionforeaseinidentifyingcor-
rect disassembly and assembly procedures.

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1
3
5
7
9
2
4
8
6
23 24
2220
18 1917
1615
1413
11 12
10
GEN
INFO SPEC
ENG
CARB
ELEC
CHAS
INSP
ADJ
TRBL
SHTG
EB003000
ILLUSTRATED SYMBOLS
Illustrated symbols 1to 8are designed as
thumb tabs to indicate the chapter’s number
and content.
1General information
2Specifications
3Periodic inspection and adjustment
4Engine
5Carburation
6Chassis
7Electrical
8Troubleshooting
Illustrated symbols 9to 16 are used to identify
the specifications appearing in the text.
9Possible to maintain with engine mounted
10 Filling fluid
11 Lubricant
12 Special tool
13 Tightening
14 Wear limit, clearance
15 Engine speed
16 Ω, V, A
Illustratedsymbols 17 to 22 in theexplodeddia-
grams indicate the types of lubricants and lu-
brication points.
17 Apply engine oil
18 Apply gear oil
19 Apply molybdenum disulfide oil
20 Apply wheel bearing grease
21 Apply lightweight lithium-soap base grease
22 Apply molybdenum disulfide grease
Illustratedsymbols 23 to 24 in theexplodeddia-
gramsindicatethewheretoapplylockingagent
23 and when to install new parts 24 .
23 Apply locking agent (LOCTITE)
24 Use new one

CONTENTS
GENERAL INFORMATION 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MOTORCYCLE IDENTIFICATION 1. . . . . . . . . . . . . . . . . . . . . . . . . . . .
FRAME SERIAL NUMBER 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ENGINE SERIAL NUMBER 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MODEL LABEL 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPECIFICATIONS 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GENERAL SPECIFICATIONS 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE SPECIFICATIONS 2. . . . . . . . . . . . . . . . . . . . . . . . . . .
CHASSIS 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ELECTRICAL 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PERIODIC INSPECTIONS AND ADJUSTMENT 3. . . . . . . . . . . . . . . . . . .
INTRODUCTION 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PERIODIC MAINTENANCE/LUBRICATION INTERVALS 3. . . . . . . .

–1–
MOTORCYCLE IDENTIFICATION GEN
INFO
NOTE:
YP100000
GENERAL INFORMATION
MOTORCYCLE IDENTIFICATION
SR100020
FRAME SERIAL NUMBER
The frame serial number 1is stamped into the
right side of the frame.
EB100030
ENGINE SERIAL NUMBER
Theengineserialnumber 1isstampedintothe
crankcase.
Designs and specifications are subject to
change without notice.
MODEL LABEL
The model label 1is affixed under the seat.
This information will be needed to order spare
parts.

–2–
GENERAL SPECIFICATIONS/
MAINTENANCE SPECIFICATIONS SPEC
SPECIFICATIONS
GENERAL SPECIFICATIONS
Model SR125
Model code: 3MW7
Dimensions:
Overall length
Wheelbase 2,020 mm
1,285 mm
Chassis:
Caster angle
Trail 27
95 mm
Electrical:
Generator system C.D.I. magneto
Bulb wattage quantity:
Headlight 12 V 35 W/35 W 1
MAINTENANCE SPECIFICATIONS
CHASSIS Item Standard Limit
Front suspension:
Oil capacity
Oil level 0.184 L (184 cm3)
140 mm (Full stroke) 

ELECTRICAL
Item Standard Limit
Ignition coil:
Primary winding resistance
Secondary winding resistance 0.184 0.276 Ωat 20C
5.68 8.52 kΩat 20C

Charging system:
Type C.D.I. magneto 
Electric starter system:
Armature coil resistance
Brash spring pressure 0.0017 0.0027 Ωat 20C
8.33 N 

Starter relay:
Model/manufacturer MS5E-661/JIDECO 
Flasher relay:
Model/manufacturer
Flasher frequency FZ264BH/DENSO
76.5 93.5 cycle/min 
