Yamaha YJ50RN Service Manual

YJ50RN

SERVICE MANUAL

LIT-11616-14-50 5LY-28197-E0

EAS00001

©2000 by Yamaha Motor Corporation, U.S.A.

Yamaha Motor Corporation, U.S.A. is expressly

YJ50RN

SERVICE MANUAL

First edition, December, 2000

All rights reserved.

Any reproduction or unauthorized use

without the written permission of

prohibited.

Printed in U.S.A.

P/N LIT-11616-14-50

EAS00002

NOTICE

This manual was produced by the Yamaha Motor 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 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.

EAS00005

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!

WARNING

CAUTION:

NOTE:

Failure to follow WARNING instructions could result in severe injury or death to
the scooter operator, a bystander or a person checking 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.

EAS00007

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.

The manual is divided into chapters. An abbreviation and symbol in the upper right corner of each

1

page indicate the current chapter. Refer to “SYMBOLS”.
Each chapter is divided into sections. The current section title is shown at the top of each page,

2

except in Chapter 3 (“PERIODIC CHECKS AND ADJUSTMENTS”), where the sub-sect ion title(s)
appears.

Sub-section titles appear in smaller print than the section title.

3

To help identify parts and clarify procedure steps, there are exploded diagrams at the start of

4

each removal and disassembly section.
Numbers are given in the order of the jobs in the exploded diagram. A circled number indicates a

5

disassembly step.
Symbols indicate parts to be lubricated or replaced. Refer to “SYMBOLS”.

6

A job instruction chart accompanies the exploded diagram, providing the order of jobs, names of

7

parts, notes in jobs, etc.
Jobs requiring more information (such as special tools and technical data) are described sequen-

8

tially.

12

GEN

SPEC

INFO

34

CHK

ENG

ADJ

56

CARB

78

CHAS

EAS00009

SYMBOLS

The following symbols are not relevant to
every vehicle.
Symbols1 to 8 indicate the subject of each
chapter.

General information

1

Specifications

2

Periodic checks and adjustments

3

Engine

4

Carburetor(s)

5

Chassis

6

Electrical system

7

Troubleshooting

8

–+

TRBL

ELEC

SHTG

90

AB

CD

T

.

R

.

EF

GHI

LS

G

M

M

E

JKL

B

Symbols9 to F indicate the following.

Serviceable with engine mounted

9

Filling fluid

0

Lubricant

A

Special tool

B

Tightening torque

C

Wear limit, clearance

D

Engine speed

E

Electrical data

F

SymbolsG to L in the exploded diagrams
indicate the types of lubricants and lubrication
points.

Engine oil

G

Gear oil

H

Molybdenum disulfide oil

I

Wheel bearing grease

J

Lithium soap base grease

K

Molybdenum disulfide grease

L

MN

LT

New

SymbolsM to N in the exploded diagrams
indicate the following.

®

Apply locking agent (LOCTITE

M

Replace the part

N

)

EAS00011

1
2
3
4
5
6
7
8

TABLE OF CONTENTS

GENERAL INFORMATION

SPECIFICATIONS
PERIODIC CHECKS AND

ADJUSTMENTS
CHASSIS

ENGINE

GEN

INFO

SPEC

CHK

ADJ

CHAS

ENG

CARBURETION

ELECTRICAL SYSTEM

TROUBLESHOOTING

CARB

–+

ELEC

TRBL

SHTG

MEMO

CONTENTS

CHAPTER 1

GENERAL INFORMATION

SCOOTER IDENTIFICATION

VEHICLE IDENTIFICATION NUMBER .....................................................1-1

MODEL CODE...........................................................................................1-1

IMPORTANT INFORMATION

PREPARATION FOR REMOVAL AND DISASSEMBLY...........................1-2

REPLACEMENT PARTS...........................................................................1-2

GASKETS, OIL SEALS AND O-RINGS ....................................................1-2

LOCK WASHERS/PLATES AND COTTER PINS .....................................1-2

BEARINGS AND OIL SEALS....................................................................1-3

CIRCLIPS ..................................................................................................1-3

CHECKING THE CONNECTIONS............................................................1-4

SPECIAL TOOLS

............................................................................................1-5

..........................................................................1-1

..........................................................................1-2

CHAPTER 2

SPECIFICATIONS

GENERAL SPECIFICATIONS

.........................................................................2-1

ENGINE SPECIFICATIONS

CHASSIS SPECIFICATIONS

ELECTRICAL SPECIFICATIONS

CONVERSION TABLE

GENERAL TIGHTENING TORQUE SPECIFICATIONS

TIGHTENING TORQUES

ENGINE TIGHTENING TORQUES.........................................................2-12

CHASSIS TIGHTENING TORQUES.......................................................2-13

LUBRICATION POINTS AND LUBRICANT TYPES

ENGINE...................................................................................................2-14

CHASSIS ................................................................................................2-15

CABLE ROUTING

.........................................................................................2-16

...........................................................................2-2

..........................................................................2-6

...................................................................2-9

..................................................................................2-11

...............................2-11

..............................................................................2-12

.....................................2-14

CHAPTER 3

1
2
3
4
5
6
7
8

PERIODIC CHECKS AND ADJUSTMENTS

INTRODUCTION

PERIODIC MAINTENANCE AND LUBRICATION INTERVALS

SIDE COVERS AND FOOTREST BOARD

FRONT PANEL AND LEG SHIELD

ADJUSTING THE ENGINE IDLING SPEED .............................................3-7

ADJUSTING THE THROTTLE CABLE FREE PLAY.................................3-8

BLEEDING THE AUTOLUBE PUMP.........................................................3-9

CHECKING THE SPARK PLUG..............................................................3-10

MEASURING THE COMPRESSION PRESSURE..................................3-11

CHECKING THE ENGINE OIL LEVEL....................................................3-13

REPLACING THE TRANSMISSION OIL.................................................3-14

CLEANING THE AIR FILTER ELEMENT................................................3-16

CHECKING THE CARBURETOR JOINT................................................3-17

CHECKING THE FUEL AND VACUUM HOSES.....................................3-17

CHECKING THE CRANKCASE BREATHER HOSE...............................3-18

CHECKING THE EXHAUST SYSTEM....................................................3-18

CHASSIS

ADJUSTING THE FRONT BRAKE..........................................................3-19

ADJUSTING THE REAR BRAKE............................................................3-19

CHECKING THE BRAKE SHOES...........................................................3-20

CHECKING AND ADJUSTING THE STEERING HEAD .........................3-20

CHECKING THE FRONT SHOCK ABSORBER .....................................3-22

CHECKING THE TIRES..........................................................................3-22

CHECKING THE WHEELS .....................................................................3-25

CHECKING AND LUBRICATING THE CABLES.....................................3-26

LUBRICATING THE LEVERS .................................................................3-26

LUBRICATING THE CENTERSTAND ....................................................3-26

ELECTRICAL SYSTEM

CHECKING AND CHARGING THE BATTERY.......................................3-27

CHECKING THE FUSE...........................................................................3-34

REPLACING THE HEADLIGHT BULB....................................................3-35

ADJUSTING THE HEADLIGHT BEAM ...................................................3-36

.......................................................................................................3-19

..............................................................................................3-1

....................3-1

.....................................................3-3

................................................................3-5

.................................................................................3-27

GEN

INFO

SPEC

CHK

ADJ

CHAS

ENG

CARB

–+

ELEC

TRBL

SHTG

CHAPTER 4

CHASSIS

FRONT WHEEL AND BRAKE

CHECKING THE FRONT WHEEL ............................................................4-5

CHECKING THE SPEEDOMETER GEAR UNIT.......................................4-6

CHECKING THE BRAKE ..........................................................................4-7

ASSEMBLING THE BRAKE SHOE PLATE ..............................................4-8

INSTALLING THE FRONT WHEEL ..........................................................4-8

REAR WHEEL AND BRAKE

CHECKING THE REAR WHEEL.............................................................4-12

CHECKING THE BRAKE ........................................................................4-12

INSTALLING THE BRAKE SHOE PLATE...............................................4-13

INSTALLING THE BRAKE SHOES.........................................................4-14

INSTALLING THE REAR WHEEL...........................................................4-14

FRONT SHOCK ABSORBER ASSEMBLIES

CHECKING THE FRONT SHOCK ABSORBER ASSEMBLIES..............4-16

INSTALLING THE RELAY ARM..............................................................4-16

HANDLEBAR

REMOVING THE HANDLEBAR..............................................................4-19

CHECKING THE HANDLEBAR...............................................................4-19

INSTALLING THE HANDLEBAR.............................................................4-20

.................................................................................................4-17

........................................................................4-1

.........................................................................4-10

...............................................4-15

STEERING HEAD

REMOVING THE FORK..........................................................................4-24

CHECKING THE STEERING HEAD .......................................................4-24

INSTALLING THE STEERING HEAD .....................................................4-25

REAR SHOCK ABSORBER ASSEMBLY

REMOVING THE REAR SHOCK ABSORBER ASSEMBLY...................4-27

CHECKING THE REAR SHOCK ABSORBER ASSEMBLY....................4-27

INSTALLING THE REAR SHOCK ABSORBER ASSEMBLY..................4-27

..........................................................................................4-22

.....................................................4-26

CHAPTER 5

1
2
3
4
5
6
7
8

ENGINE

ENGINE REMOVAL

INSTALLING THE ENGINE.......................................................................5-3

CYLINDER HEAD, CYLINDER AND PISTON

REMOVING THE CYLINDER AND PISTON.............................................5-6

CHECKING THE CYLINDER HEAD .........................................................5-6

CHECKING THE CYLINDER AND PISTON..............................................5-7

CHECKING THE PISTON RINGS.............................................................5-8

CHECKING THE PISTON PIN ..................................................................5-9

INSTALLING THE PISTON AND CYLINDER .........................................5-11

KICKSTARTER

SHEAVES COVER .................................................................................5-13

CHECKING THE KICKSTARTER ...........................................................5-15

INSTALLING THE KICKSTARTER .........................................................5-15

BELT DRIVE

REMOVING THE SECONDARY PULLEY AND V-BELT ........................5-19

REMOVING THE PRIMARY SHEAVE....................................................5-20

DISASSEMBLING THE SECONDARY PULLEY.....................................5-20

CHECKING THE CLUTCH SHOES ........................................................5-20

CHECKING THE SECONDARY PULLEY............................................... 5-21

CHECKING THE V-BELT........................................................................5-22

CHECKING THE PRIMARY PULLEY WEIGHTS....................................5-22

ASSEMBLING THE SECONDARY PULLEY...........................................5-23

INSTALLING THE PRIMARY PULLEY ...................................................5-24

INSTALLING THE BELT DRIVE..............................................................5-25

.................................................................................................5-16

.........................................................................................5-1

...............................................5-4

..............................................................................................5-13

GEN

INFO

SPEC

CHK

ADJ

CHAS

ENG

CARB

STARTER CLUTCH AND STARTER MOTOR

CHECKING THE STARTER CLUTCH ....................................................5-28

INSTALLING THE STARTER CLUTCH ..................................................5-28

TRANSMISSION

CHECKING THE TRANSMISSION .........................................................5-32

GENERATOR AND AUTOLUBE PUMP

STATOR COIL ASSEMBLY ...................................................................5-33

AUTOLUBE PUMP..................................................................................5-34

REMOVING THE GENERATOR .............................................................5-35

CHECKING THE AUTOLUBE PUMP......................................................5-35

INSTALLING THE AUTOLUBE PUMP....................................................5-35

INSTALLING THE GENERATOR............................................................5-36

...........................................................................................5-30

............................................5-27

.......................................................5-33

–+

ELEC

TRBL

SHTG

CRANKCASE ................................................................................................5-37

DISASSEMBLING THE CRANKCASE....................................................5-39

CHECKING THE CRANKCASE ..............................................................5-39

CHECKING THE BEARINGS AND OIL SEALS......................................5-40

CHECKING THE REED VALVE..............................................................5-40

ASSEMBLING THE CRANKCASE..........................................................5-41

CRANKSHAFT ..............................................................................................5-42

REMOVING THE CRANKSHAFT ASSEMBLY .......................................5-43

CHECKING THE CRANKSHAFT ............................................................5-43

INSTALLING THE CRANKSHAFT ..........................................................5-44

CHAPTER 6

CARBURETION

CARBURETOR................................................................................................6-1

CHECKING THE CARBURETOR .............................................................6-4

ASSEMBLING THE CARBURETOR.........................................................6-5

INSTALLING THE CARBURETOR ...........................................................6-6

MEASURING AND ADJUSTING THE FLOAT HEIGHT............................6-7

CHECKING THE AUTOCHOKE ASSEMBLY ...........................................6-7

CHECKING THE FUEL COCK OPERATION............................................6-8

CHAPTER 7

ELECTRICAL

ELECTRICAL COMPONENTS........................................................................7-1

SWITCHES ......................................................................................................7-2

CHECKING SWITCH CONTINUITY..........................................................7-2

CHECKING THE SWITCHES..........................................................................7-3

CHECKING THE BULBS AND BULB SOCKETS ..........................................7-5

TYPES OF BULBS ....................................................................................7-5

CHECKING THE CONDITION OF THE BULBS........................................7-6

CHECKING THE CONDITION OF THE BULB SOCKETS........................7-7

IGNITION SYSTEM..........................................................................................7-8

CIRCUIT DIAGRAM ..................................................................................7-8

TROUBLESHOOTING...............................................................................7-9

ELECTRIC STARTING SYSTEM ..................................................................7-13

CIRCUIT DIAGRAM ................................................................................7-13

TROUBLESHOOTING.............................................................................7-14

STARTER MOTOR........................................................................................7-17

1
2
3
4
5
6
7
8

CHECKING THE STARTER MOTOR .....................................................7-19

ASSEMBLING THE STARTER MOTOR.................................................7-20

CHARGING SYSTEM....................................................................................7-21

CIRCUIT DIAGRAM ................................................................................7-21

TROUBLESHOOTING.............................................................................7-22

LIGHTING SYSTEM ......................................................................................7-24

CIRCUIT DIAGRAM ................................................................................7-24

TROUBLESHOOTING.............................................................................7-25

CHECKING THE LIGHTING SYSTEM....................................................7-26

SIGNALING SYSTEM....................................................................................7-29

CIRCUIT DIAGRAM ................................................................................7-29

TROUBLESHOOTING.............................................................................7-31

CHECKING THE SIGNALING SYSTEM .................................................7-32

AUTO CHOKE SYSTEM ...............................................................................7-39

CIRCUIT DIAGRAM ................................................................................7-39

TROUBLESHOOTING.............................................................................7-40

GEN

INFO

SPEC

CHK

ADJ

CHAS

CHAPTER 8

TROUBLESHOOTING

STARTING FAILURE/HARD STARTING........................................................8-1

ENGINE.....................................................................................................8-1

FUEL SYSTEM..........................................................................................8-1

ELECTRICAL SYSTEMS ..........................................................................8-1

INCORRECT ENGINE IDLING SPEED...........................................................8-2

ENGINE.....................................................................................................8-2

FUEL SYSTEM..........................................................................................8-2

ELECTRICAL SYSTEMS ..........................................................................8-2

POOR MEDIUM-AND-HIGH-SPEED PERFORMANCE .................................8-2

ENGINE.....................................................................................................8-2

FUEL SYSTEM..........................................................................................8-2

FAULTY CLUTCH ...........................................................................................8-2

ENGINE OPERATES BUT SCOOTER WILL NOT MOVE........................8-2

CLUTCH SLIPS.........................................................................................8-2

POOR STARTING PERFORMANCE........................................................8-2

POOR SPEED PERFORMANCE..............................................................8-2

ENG

CARB

–+

ELEC

TRBL

SHTG

OVERHEATING...............................................................................................8-3

ENGINE.....................................................................................................8-3

FUEL SYSTEM..........................................................................................8-3

CHASSIS...................................................................................................8-3

ELECTRICAL SYSTEMS ..........................................................................8-3

POOR BRAKING PERFORMANCE................................................................8-3

UNSTABLE HANDLING..................................................................................8-3

FAULTY LIGHTING OR SIGNALING SYSTEM..............................................8-4

HEADLIGHT DOES NOT LIGHT...............................................................8-4

HEADLIGHT BULB BURNT OUT..............................................................8-4

TAIL/BRAKE LIGHT DOES NOT LIGHT...................................................8-4

TAIL/BRAKE LIGHT BULB BURNT OUT..................................................8-4

TURN SIGNAL DOES NOT LIGHT ...........................................................8-4

TURN SIGNAL BLINKS SLOWLY.............................................................8-4

TURN SIGNAL REMAINS LIT...................................................................8-4

TURN SIGNAL BLINKS QUICKLY............................................................8-4

HORN DOES NOT SOUND ......................................................................8-4

SCOOTER IDENTIFICATION

1

EAS00015

GENERAL INFORMATION

SCOOTER IDENTIFICATION

1

EAS00017

VEHICLE IDENTIFICATION NUMBER

The vehicle identification number 1 is
stamped into the frame.

EAS00018

MODEL CODE

The model code label 1 is affixed to the loca­tion shown in the figure. Record the informa­tion on this label in the space provided. This
information will be needed to order spare
parts.

GEN

INFO

1 - 1

IMPORTANT INFORMATION

EAS00020

IMPORTANT INFORMATION

PREPARATION FOR REMOVAL AND
DISASSEMBLY

1. Before removal and disassembly, remove all
dirt, mud, dust and foreign material.

2. Use only the proper tools and cleaning
equipment.
Refer to “SPECIAL TOOLS”.

3. When disassembling, always keep mated
parts together. This includes gears, cylin­ders, pistons and other parts that have been
“mated” through normal wear. Mated parts
must always be reused or replaced as an
assembly.

4. During disassembly, clean all of the parts
and place them in trays in the order of dis­assembly. This will speed up assembly and
allow for the correct installation of all parts.

5. Keep all parts away from any source of fire.

EAS00021

REPLACEMENT PARTS

Use only genuine Yamaha parts for all
replacements. Use oil and grease recom­mended by Yamaha for all lubrication jobs.
Other brands may be similar in function and
appearance, but inferior in quality.

GEN

INFO

EAS00022

GASKETS, OIL SEALS AND O-RINGS

1. When overhauling the engine, replace all
gaskets, seals and O-rings. All gasket sur­faces, oil seal lips and O-rings must be
cleaned.

2. During reassembly, properly oil all mating
parts and bearings and lubricate the oil seal
lips with grease.

EAS00023

LOCK WASHERS/PLATES AND COTTER
PINS

After removal, replace all lock washers/plates

1

and cotter pins. After the bolt or nut has
been tightened to specification, bend the lock
tabs along a flat of the bolt or nut.

1 - 2

IMPORTANT INFORMATION

1

EAS00024

BEARINGS AND OIL SEALS

Install bearings and oil seals so that the manu­facturer’s marks or numbers are visible. When
installing oil seals, lubricate the oil seal lips
with a light coat of lithium soap base grease.
Oil bearings liberally when installing, if appro­priate.

Oil seal

1

CAUTION:

@

Do not spin the bearing with compressed
air because this will damage the bearing
surfaces.

Bearing

1

GEN

INFO

EAS00025

CIRCLIPS

Before reassembly, check all circlips carefully
and replace damaged or distorted circlips.
Always replace piston pin clips after one use.
When installing a circlip 1, make sure the
sharp-edged corner 2 is positioned opposite
the thrust 3 that the circlip receives.

Shaft

4

1 - 3

IMPORTANT INFORMATION

EAS00026

CHECKING THE CONNECTIONS

Check the leads, couplers, and connectors for
stains, rust, moisture, etc.

1. Disconnect:

• lead

• coupler

• connector

2. Check:

• lead

• coupler

• connector
Moisture → Dry with an air blower.
Rust/stains→ Connect and disconnect sev­eral times.

GEN

INFO

3. Check:

• all connections
Loose connection → Connect properly.

NOTE:

@

If the pin 1 on the terminal is flattened, bend it
up.

4. Connect:

• lead

• coupler

• connector

NOTE:

@

Make sure all connections are tight.

5. Check:

• continuity
(with the pocket tester)

Pocket tester

YU-03112

NOTE:

@

• If there is no continuity, clean the terminals.

• When checking the wire harness, perform
steps (1) to (3).

• As a quick remedy, use a contact revitalizer
available at most part stores.

1 - 4

GEN

1

SPECIAL TOOLS

EAS00027

SPECIAL TOOLS

The following special tools are necessary for complete and accurate tune-up and assembly. Use
only the appropriate special tools as this will help prevent damage caused by the use of inappropri­ate tools or improvised techniques. Special tools, part numbers or both may differ depending on the
country.
When placing an order, refer to the list provided below to avoid any mistakes.

Tool No. Tool name/Function Illustration

Oil seal guide

YM-01409

This tool is used to install oil seals.
Crankshaft installer spacer

YM-01411

This tool is used to install the crank­shaft.

Dynamic spark tester

INFO

YM-34487

YS-28891

YU-01135

YU-01235

This tool is used to check the ignition
system components.

Clutch spring holder

This tool is used to disassembly and
assembly the secondary pulley.

Crankcase separating tool

This tool is used to remove the crank­shaft and to separate the crankcase.

Rotor holding tool

This tool is used to hold the generator
rotor when removing or installing the
generator rotor bolt.

Steering nut wrench (45 mm)

YU-01444

This tool is used to loosen and tighten
the lower steering stem nut.

1 - 5

GEN

SPECIAL TOOLS

Tool No. Tool name/Function Illustration

Sheave holder

INFO

YU-01701

YU-03112

YU-33223

YU-33975

This tool is used to hold the clutch hous­ing when removing or installing the
clutch housing nut.

Pocket tester

This tool is used to check the electrical
system.

Compression gauge

This tool is used to measure engine
compression.

Steering nut wrench

This tool is used to loosen or tighten the
steering stem ring nut.

Inductive tachometer

YU-8036-A

Crankshaft installer tool

set

YU-90050

Crankshaft installer pot

YU-90058

Crankshaft installer bolt

YU-90060

YU-90062

YU-90105

This tool is used to check engine speed.
Crankshaft installer tool set

Crankshaft installer pot
Crankshaft installer bolt

These tools are used to install the
crankshaft.

Crankshaft installer adaptor (M10)

This tool is used to install the crank­shaft.

Flywheel puller set

This tool is used to remove the genera­tor rotor.

1 - 6

GEN

1

SPECIAL TOOLS

Tool No. Tool name/Function Illustration

Quick Gasket

®

INFO

ACC-1100-15-01

This sealant is used to seal to mating
surfaces (e.g., crankcase mating sur­faces).

1 - 7

GENERAL SPECIFICATIONS

SPEC

SPECIFICATIONS

GENERAL SPECIFICATIONS

Item Standard Limit

Model code
Dimensions

Overall length 1,630 mm (64.1 in) ---­Overall width 630 mm (24.8 in) ---­Overall height 1,030 mm (40.5 in) ---­Seat height 715 mm (28.1 in) ---­Wheelbase 1,150 mm (45.3 in) ---­Minimum ground clearance 85 mm (3.3 in) ---­Minimum turning radius 1,600 mm (63 in) ----

Weight

Wet (with oil and a full fuel tank) 74 kg (163 lb) ----

5LY1 ----

2 - 1

ENGINE SPECIFICATIONS

2

SPEC

ENGINE SPECIFICATIONS

Item Standard Limit

Engine

Engine type Air-cooled, 2-stroke ---­Induction system Reed valve ---­Displacement 49 cm
Cylinder arrangement Forward inclined single cylinder ---­Bore× stroke 40.0 × 39.2 mm (1.57 × 1.54 in) ---­Compression ratio 7.3 : 1 ---­Engine idling speed 1,800 r/min ----

Fuel

Recommended fuel Unleaded fuel ---­Fuel tank capacity

Total (including reserve) 6 L (5.3 Imp qt, 6.3 US qt) ----

Engine oil

Lubrication system Separate lubrication (Yamaha autolube) ---­Oil type or grade Yamalube 2-cycle oil or

Quantity

Capacity 1.4 L (1.23 Imp qt, 1.48 US qt) ---­Air filter oil grade Foam air-filter oil or SAE 10W30SE ----

Transmission

Recommended oil Yamalube 4 (10W30) or SAE 10W30 type

Periodic oil change 0.1 L (0.09 Imp qt, 0.11 US qt) ----

Total amount 0.11 L (0.1 Imp qt, 0.12 US qt) ----

Starting system type
Spark plug

Model (manufacturer) × quantity BPR7HS (NGK) ---­Spark plug gap 0.6 ~ 0.7 mm (0.02 ~ 0.03 in) ----

Cylinder head

Max. warpage ---- 0.02 mm

Cylinder

Cylinder arrangement Forward inclined single cylinder ---­Bore× stroke 40.0 × 39.2 mm (1.57 × 1.54 in) ---­Compression ratio 7.3 : 1 ---­Bore 39.993 ~ 40.012 mm (1.5745 ~ 1.5753 in) ---­Max. taper ---- 0.05 mm

Max. out-of-round ---- 0. 05 mm

3

----

2-stroke engine oil

SE motor oil

Electric and kick starter ----

(0.0008 in)

(0.002 in)

(0.002 in)

----

----

----

2 - 2

ENGINE SPECIFICATIONS

SPEC

Item Standard Limit

Piston

Piston-to-cylinder clearance 0.03 ~ 0.05 mm (0.0012 ~ 0.0020 in) 0.10 mm

(0.0039 in)

Diameter D 39.952 ~ 39.969 mm (1.5729 ~ 1.5736 in) ----

H

D

Height H 5 mm (0.2 in) ---­Oversize 1st ---- ---­Oversize 2nd ---- ---­Piston pin bore (in the piston)

Diameter 10.004 ~ 10.015 mm (0.3939 ~ 0.3943 in) 10.045 mm

(0.3955 in)

Offset 0 mm (0 in) ----

Piston pin

Outside diameter 9.996 ~ 10.000 mm (0.3935 ~ 0.3937 in) 9.976 mm

(0.3928 in)
Piston-pin-to-piston-pin-bore clear­ance

0.004 ~ 0.019 mm (0.00016 ~ 0.00075 in) 0.069 mm
(0.0027 in)

Piston ring

Top ring

B

T

Ring type Keystone ---­Dimensions (B × T) 1.2 × 1.8 mm (0.05 × 0.07 in) ---­End gap (installed) 0.15 ~ 0.35 mm (0.006 ~ 0.014 in) 0.70 mm

(0.028 in)

Ring side clearance 0.03 ~ 0.05 mm (0.0012 ~ 0.0020 in) 0.10 mm

(0.0039 in)

2nd ring

B

T

Ring type Keystone ---­Dimensions (B × T) 1.2 × 1.8 mm (0.05 × 0.07 in) ---­End gap (installed) 0.15 ~ 0.35 mm (0.006 ~ 0.014 in) 0.70 mm

(0.028 in)

Ring side clearance 0.03 ~ 0.05 mm (0.0012 ~ 0.0020 in) 0.10 mm

(0.0039 in)

2 - 3

Crankshaft

2

ENGINE SPECIFICATIONS

Item Standard Limit

F

SPEC

C

Width A 37.90 ~ 37.95 mm (1.492 ~ 1.494 in) ---­Max. runout C ---- 0.03 mm

Big end side clearance D 0.35 ~ 0.75 mm (0.0138 ~ 0.0295 in) 1.0 mm

Big end radial clearance E 0.004 ~ 0.017 mm (0.00016 ~ 0.00067 in) ---­Small end free play F 0.4 ~ 0.8 mm (0.02 ~ 0.03 in) ----

Clutch

Clutch type Dry, centrifugal automatic ---­Clutch shoe

Thickness 4.0 mm (0.157 in) 1.0 mm

Clutch shoe spring

Free length 29.9 mm (1.18 in) ----

Kickstarter

Kickstarter type Ratchet ---­Kickstarter pinion gear clip force 0.15 ~ 0.25 kg (0.34 ~ 0.56 lb) ----

Transmission

Transmission type V-belt automatic ---­Primary reduction system Helical ---­Primary reduction ratio 48/13 (3.692) ---­Secondary reduction system Spur gear ---­Secondary reduction ratio 42/13 (3.231) ---­Operation Centrifugal automatic type ---­Single speed automatic 2.183 ~ 1.050:1 ----

Air filter type

C

E

D

A

(0.0012 in)

(0.0394 in)

(0.039 in)

Wet element ----

2 - 4

ENGINE SPECIFICATIONS

Item Standard Limit

Carburetor

Model (manufacturer) × quantity Y14P/1 (TEIKEI) × 1 ---­Throttle cable free play
(at the flange of the throttle grip)
ID mark 5LY1 00 ---­Main jet #64 ---­Main air jet 2.0 ---­Jet needle 3SOC-3/5 ---­Needle jet 2.090 ---­Cutaway 2.5 ---­Pilot jet #46 ---­Bypass 1 0.8 ---­Valve seat size 1.8 ---­Starter jet 1 #46 ---­Float height 15 ~ 17 mm (0.59 ~ 0.67 in) ----

Reed valve

Thickness 0.164 ~ 0.176 mm (0.0065 ~ 0.0069 in) ---­Valve stopper height 7.0 ~ 7.4 mm (0.28 ~ 0.29 in) ---­Valve bending limit 0.2 mm (0.008 in) ----

Autolube pump

Plunger diameter 2.62 mm (0.103 in) ---­Minimum stroke 0.1 mm (0.0039 in) ---­Maximum stroke 0.49 mm (0.0193 in) ----

1.5 ~ 3.5 mm (0.06 ~ 0.14 in) ----

SPEC

2 - 5

CHASSIS SPECIFICATIONS

2

SPEC

CHASSIS SPECIFICATIONS

Item Standard Limit

Frame

Frame type Steel tube underbone ---­Caster angle 25° ---­Trail 71 mm (2.8 in) ----

Front wheel

Wheel type Panel wheel ---­Rim

Size 10 × 2.15 ----

Material Steel ---­Wheel travel 60 mm (2.36 in) ---­Wheel runout

Max. radial wheel runout ---- 1.0 mm

(0.04 in)

Max. lateral wheel runout ---- 1.0 mm

(0.04 in)

Rear wheel

Wheel type Panel wheel ---­Rim

Size 10 × 2.15 ----

Material Steel ---­Wheel travel 46 mm (1.81 in) ---­Wheel runout

Max. radial wheel runout ---- 1.0 mm

(0.04 in)

Max. lateral wheel runout ---- 1.0 mm

(0.04 in)

Front tire

Tire type Tubeless ---­Size 80/90-10 (34J) ---­Model (manufacturer) MB38/C-922 (INOUE/CHENG SHIN) ---­Tire pressure (cold)

0 ~ 90 kg (0 ~ 198 lb) 150 kPa (1.50 kg/cm
Min. tire tread depth ---- 1.0 mm

Rear tire

Tire type Tubeless ---­Size 80/90-10 (34J) ---­Model (manufacturer) MB3 8 / C - 9 2 2 ( I N O U E /C H E N G S H I N ) ---­Tire pressure (cold)

0 ~ 90 kg (0 ~ 198 lb) 175 kPa (1.75 kg/cm
Min. tire tread depth ---- 1.0 mm

2

, 21.8 psi) ----

(0.04 in)

2

, 25.4 psi) ----

(0.04 in)

2 - 6

CHASSIS SPECIFICATIONS

Item Standard Limit

Front brake

Brake type Drum brake ---­Operation Right-hand operation ---­Brake lever free play (at lever end) 10 ~ 20 mm (0.39 ~ 0.79 in) ---­Dram brake type Leading, trailing ----

Brake drum inside diameter 110 mm (4.33 in) 110.5 mm

Lining thickness 4 mm (0.16 in) 2 mm

Rear brake

Brake type Drum brake ---­Operation Left-hand operation ---­Brake lever free play (at lever end) 10 ~ 20 mm (0.39 ~ 0.79 in) ---­Drum brake type Leading, trailing ----

Brake drum inside diameter 110 mm (4.33 in) 110.5 mm

Lining thickness 4 mm (0.16 in) 2 mm

Front suspension

Suspension type Bottom link fork ---­Front fork type Coil spring/oil damper ---­Front fork travel 40 mm (1.57 in) ---­Spring

Free length 156.5 mm (6.16 in) 153.4 mm

Spring rate (K1) 12.8 N/mm (1.28 kgf/mm, 73.09 lb/in) ----

Spring stroke (K1) 0 ~ 20 mm (0 ~ 0.79 in) ----

Spring rate (K2) 30.4 N/mm (3.04 kgf/mm, 173.58 lb/in) ----

Spring stroke (K2) 20 ~ 30 mm (0.79 ~ 1.18 in) ----

Spring rate (K3) 67.6 N/mm (6.76 kgf/mm, 386 lb/in) ----

Spring stroke (K3) 30 ~ 40 mm (1.18 ~ 1.57 in) ---­Optional spring available No ----

Steering

Steering bearing type Ball and race bearing ----

SPEC

(4.35 in)

(0.08 in)

(4.35 in)

(0.08 in)

(6.04 in)

2 - 7

CHASSIS SPECIFICATIONS

2

Item Standard Limit

Rear suspension

Suspension type Unit swing ---­Rear shock absorber assembly type Coil spring/oil damper ---­Rear shock absorber assembly travel 45 mm (1.77 in) ---­Spring

Free length 173.5 mm (6.83 in) 170.0 mm

Installed length 166.5 mm (6.56 in) ----

Spring rate (K1) 34.5 N/mm (3.45 kgf/mm, 197 lb/in) ----

Spring stroke (K1) 0 ~ 45 mm (0 ~ 1.77 in) ---­Optional spring available No ----

SPEC

(6.69 in)

2 - 8

ELECTRICAL SPECIFICATIONS

SPEC

ELECTRICAL SPECIFICATIONS

Item Standard Limit

System voltage
Ignition system

Ignition system type DC.CDI ---­Ignition timing 14° BTDC at 5,000 r/min ---­Advancer type Fixed ---­Pickup coil resistance/color 248 ~ 372 Ω/W/L–W/R ---­CDI unit model (manufacturer) 5BM (YAMAHA) ----

Ignition coil

Model (manufacturer) 2JN (YAMAHA) ---­Minimum ignition spark gap 6 mm (0.24 in) ---­Primary coil resistance 0.18 ~ 0.28 Ω ---­Secondary coil resistance 6.32 ~ 9.48 kΩ ----

Spark plug cap

Material Resin ---­Resistance 5 kΩ ----

Charging system

System type AC magneto ---­Model (manufacturer) F5BM (YAMAHA) ---­Standard output 14 V/120 W at 5,000 r/min ---­Stator coil resistance (W-B) 0.29 ~ 0.43 Ω ----

Voltage regulator

Regulator type Semiconductor, short circuit ---­Model (manufacturer) SH671-12 (SHINDENGEN) ---­No-load regulated voltage (DC) 14.0 ~ 15.0 V ---­No-load regulated voltage (AC) 12.3 ~ 13.3 V ----

Rectifier

Model (manufacturer) SH671-12 (SHINDENGEN) ---­Rectifier capacity (DC) 8 A ---­Rectifier capacity (AC) 12 A ---­Withstand voltage 200 V ----

Battery

Battery type GT4B-5 ---­Battery voltage/capacity 12 V/2.5 AH ---­Specific gravity 1.350 ----

Headlight type
Indicator light type × quantity
Bulbs (voltage/wattage × quantity)

Headlight 12 V 35 W/35 W × 1 ---­Tail/brake light 12 V 27 W/8 W × 1 ---­Front turn signal light 12 V 10 W × 2 ---­Rear turn signal light 12 V 10 W × 2 ---­Meter light 12 V 1.7 W × 1 ---­Fuel level indicator light 14 V 1.4 W × 1 ---­High beam indicator light 12 V 1.7 W × 1 ---­Oil level indicator light 12 V 1.7 W × 1 ---­Turn indicator light 14 V 3 W × 1 ----

12 V ----

Halogen bulb ---­Bulb type × 3 ----

2 - 9