Yamaha 2008 YW50X User manual

2008
MOTORCYCLE
SERVICE MANUAL
Model : YW50X_
5PNF81972100 *5PNF81972100*

EAS00000
YW50X 2007
SUPPLEMENTARY SERVICE MANUAL
©2007 by Yamaha Motor Taiwan Co., Ltd.
First edition, June 2007
All rights reserved.
Any reproduction or unauthorized use
without the written permission of
Yamaha Motor Taiwan Co., Ltd.
is expressly prohibited.
Printed in CANADA
FORWORD
This supplementary service manual has been prepared to introduce new service and data forYW50BP
2001. For complete service manual procedures it is necessary to use this supplementary service
manual together with the following manual.
YW50BP 2001 SERVICE MANUAL : 5PN1-ME1

EAS00002
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.
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!
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 dam-
age to the scooter.
A NOTE provides key information to make procedures easier or clearer.
NOTE:
w
cC
Q

4-3
ENG
CYLINDER HEAD, CYLINDER AND PISTON
CYLINDER HEAD, CYLINDER AND PISTON
Job name/Part name
Cylinder head, Cylinder and piston
removal
Engine
Muffler/Gasket
Air shroud 2
Spark plug
Cylinder head/Cylinder head gasket
Cylinder
Piston pin clip
Piston pin/ Bearing
Piston
Piston ring set
Cylinder gasket
Remarks
Remove the parts in the order.
Refer to the “ENGINE REMOVAL” sec-
tion
Reverse the removal procedure for in-
stallation.
Order
1
2
3
4
5
6
7
8
9
10
Q’ty
1/1
1
1
1/1
1
2
1/1
1
1
1
4
5
6
7
10 1
2
3
26Nm(2.6 m.kg, 18.2 ft.lb)
T
R
.
.
14Nm(1.4 m.kg, 10 ft.lb)
T
R
.
.
9Nm(0.9 m.kg,6.5 ft.lb)
T
R
.
.
New
New
New
E
8
9
CYLINDER HEAD, CYLINDER AND PISTON
4-4
ENG
PISTON PIN AND PISTON REMOVAL
1. Remove:
8Piston pin clip 1
NOTE:
Before removing the piston pin clip, cover the
crankcase with a clean rag so you will not acci-
dentally drop the clip into the crankcase.
2. Remove:
8Piston pin 1
8Piston 2
8Piston pin bearing 3
cC
Do not use a hammer to drive the piston pin
out.
CYLINDER HEAD INSPECTION
1. Eliminate:
8Carbon deposits
Use a rounded scrapper 1.
2. Inspect:
8Cylinder head warpage
Out of specification∅Re-surface.
*************************************
Warpage measurement and re-surfacement
steps:
8Attach a straight edge 1and a thickness
gauge 2on the cylinder head.
8Measure the warpage limit.
Warpage limit:
0.03 mm(0.0012 in)
8If the warpage is out of specification, reface
the cylinder head.
NOTE:
Rotate the head severai tires to avoid remov-
ing too much material from one side.
*************************************
CYLINDER HEAD, CYLINDER, PISTON
2
1
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.
1The manual is divided into chapters. An abbreviation and symbol in the upper right corner of
each page indicate the current chapter.
Refer to “SYMBOLS”.
2Each 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.
3Sub-section titles appear in smaller print than the section title.
4To help identify parts and clarify procedure steps, there are exploded diagrams at the start of
each removal and disassembly section.
5Numbers are given in the order of the jobs in the exploded diagram. A circled number indicates
a disassembly step.
6Symbols indicate parts to be lubricated or replaced.
Refer to “SYMBOLS”.
7A job instruction chart accompanies the exploded diagram, providing the order of jobs, names of
parts, notes in jobs, etc.
8Jobs requiring more information (such as special tools and technical data) are described se-
quentially.
8
4
5
7
1
3
26

GEN
INFO
SPEC
CHK
ADJ
ENG
TRBL
SHTG
CHAS
-+
ELEC
4M
B
LS
New
M
G
COOL
12
34
56
78
90
qw
er
i
s
hj
EAS00008
SYMBOLS
The following symbols are not relevant to every
vehicle.
Symbols 1to 9indicate the subject of each
chapter.
1General information
2Specifications
3Periodic checks and adjustments
4Chassis
5Engine
6Cooling system
7Carburetor
8Electrical system
9Troubleshooting
Symbols 0to uindicate the following.
0Serviceable with engine mounted
qFilling fluid
wLubricant
eSpecial tool
rTightening torque
tWear limit, clearance
yEngine speed
uElectrical data
Symbols ito gin the exploded diagrams indi-
cate the types of lubricants and lubrication
points.
iEngine oil
oGear oil
pMolybdenum-disulfide oil
aBrake fluid
sWheel-bearing grease
dLithium-soap- based grease
fMolybdenum-disulfide grease
gSilicone grease
Symbols hto jin the exploded diagrams indi-
cate the following.
hApply locking agent (LOCTITE®)
jReplace the part
T
R
.
.
t y u
LT
CARB
BF
opa
S
dfg

EAS00010
TABLE OF CONTENTS
GENERAL INFORMATION
SPECIFICATIONS
PERIODIC CHECKS AND
ADJUSTMENTS
CARBURETOR
GEN
INFO
SPEC
CHK
ADJ
CARB
1
2
3
4
5
6
5
7
8
9

1-8
GEN
INFO
CHAPTER 1
GENERAL INFORMATION
SCOOTER IDENTIFICATION ................................................................... 1-1
VEHICLE IDENTIFICATION NUMBER ............................................. 1-1
MODEL LABEL .................................................................................. 1-1
IMPORTANT INFORMATION ................................................................... 1-2
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 ............................. 1-3
BEARINGS AND OIL SEALS ............................................................ 1-3
CIRCLIPS ........................................................................................... 1-3
CHECKING THE CONNECTIONS ........................................................... 1-4
SPECIAL TOOLS ...................................................................................... 1-5

1-1
GEN
INFO
1
1
SCOOTER IDENTIFICATION
EAS00015
GENERAL INFORMATION
SCOOTER IDENTIFICATION
EAS00017
VEHICLE IDENTIFICATION NUMBER
The vehicle identification number 1is stamped
into the frame.
EAS00018
MODEL LABEL
The model label 1is affixed to the seat. This
information will be needed to order spare parts.

1-2
GEN
INFO
IMPORTANT INFORMATION
EAS00020
IMPORTANT INFORMATION
PREPARATION FOR REMOVAL AND DISAS-
SEMBLY
1. Before removal and disassembly, remove
all dirt, mud, dust and foreign material.
2. Use only the proper tools and cleaning
equipment.
Refer to the “SPECIAL TOOLS”.
3. When disassembling, always keep mated
parts together. This includes gears, cylin-
ders, 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 dis-
assembly. 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 replace-
ments. Use oil and grease recommended by
Yamaha for all lubrication jobs. Other brands may
be similar in function and appearance, but infe-
rior in quality.
EAS00022
GASKETS, OIL SEALS AND O-RINGS
1. When overhauling the engine, replace all
gaskets, seals and O-rings. All gasket sur-
faces, 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.

1-3
GEN
INFO
IMPORTANT INFORMATION
EAS00023
LOCK WASHERS/PLATES AND COTTER
PINS
After removal, replace all lock washers/plates
1and cotter pins. After the bolt or nut has been
tightened to specification, bend the lock tabs
along a flat of the bolt or nut.
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-based
grease. Oil bearings liberally when installing, if
appropriate.
1Oil seal
cC
Do not spin the bearing with compressed
air because this will damage the bearing
surfaces.
1Bearing
EAS00025
CIRCLIPS
Before reassembly, check all circlips carefully
and replace damaged or distorted circlips. Al-
ways replace piston pin clips after one use.When
installing a circlip 1, make sure the sharp-edged
corner 2is positioned opposite the thrust 3
that the circlip receives.
4Shaft

1-4
GEN
INFO
CHECKING THE CONNECTIONS
EAS00026
CHECKING THE CONNECTIONS
Check the leads, couplers, and connectors for
stains, rust, moisture, etc.
1. Disconnect:
8lead
8coupler
8connector
2. Check:
8lead
8coupler
8connector
Moisture iDry with an air blower.
Rust/stains iConnect and disconnect
several times.
3. Check:
8all connections
Loose connection iConnect properly.
NOTE:
If the pin 1on the terminal is flattened, bend it
up.
4. Connect:
8lead
8coupler
8connector
NOTE:
Make sure all connections are tight.
5. Check:
8continuity
(with the pocket tester)
Pocket tester
90890-03112(YU-03112-C)
NOTE:
8If there is no continuity, clean the terminals.
8When checking the wire harness, perform
steps (1) to (3).
8As a quick remedy, use a contact revitalizer
available at most part stores.

1-5
GEN
INFO
Tool NO. Tool name / Function Illustration
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 inappropri-
ate 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.
NOTE:
8For U.S.A. and Canada, use part number starting with “YM-”, “YU-”, or “ACC-”.
8For others, use part number starting with “90890-”.
Rotor holding tool
This tool is used to hold the generator rotor
when removing or installing and generator
rotor bolt.
Clutch spring holder
These tool are used for removing the nut with
holding the compression spring.
Crankshaft installer set 1
Adapter 2
These tools are used to install the crank-
shaft.
Flywheel puller
This tool is used to remove the generator
rotor.
Crankcase separating tool
This tool is used to remove the crankshaft
or separate the crankcase.
Oil seal guide
This tool is used for protecting the oil seal
lip when installing the secondary sliding
sheave.
Steering nut wrench
This tool is used to loosen and tighten the
steering ring nut.
Sheave holder
This tool is used for holding the secondary
sheave.
90890-01235
YU-01235
90890-01337
YM-33285
YM-33285-6
90890-01284
YU-90050
90890-01383
YU-90062
90890-01189
YU-01189
90890-01135
YU-01135-B
90890-01384
YM-33299
90890-01403
YU-A9472
90890-01701
YS-01880-A
12

1-6
GEN
INFO
Tool NO. Tool name / Function Illustration
SPECIAL TOOLS
90890-06760
90890-03112
YU-03112-C
90890-01409
YM-01409
90890-01410
YM-01410
90890-06754
YM-34487
90890-85505
ACC-11001-05-01
90890-01348
YM-01348
90890-01268
YU-01268
90890-01367
YM-A9409-7
90890-01400
YM-A9409-3
90890-01326
YM-01326
90890-01294
YM-01300-1
Digital tachometer
This tool is needed for detecting engine rpm.
Pocket tester
This instrument is invaluable for checking
the electrical system.
Oil seal guide
This tool is used to install the left side crank-
case oil seal.
Oil seal installer
This tool is used to install the left side crank-
case oil seal.
Ignition checker
This tool is used to check the ignition sys-
tem components.
Yamaha bond NO.1215
Sealant (Quick Gasket ®)
This sealant (bond) is used on crankcase
mating surfaces (e.g., crankcase mating
surfaces).
Locknut wrench
This tool is used when removing or install-
ing the secondary sheave nut.
Ring nut wrench
This tool is used to loosen and tighten the
steering ring nut.
Fork seal driver weight 1
Fork seal driver attachment 2
These tools are used when installing the fork
seal.
T-handle 1
Damper rod holder 2
These tools are used to hold the damper rod
when removing or installing the damper rod.
12
12
41
46

1-7
GEN
INFO
Tool NO. Tool name / Function Illustration
SPECIAL TOOLS
90890-01312
YM-01312-A
Fuel level gauge
This gauge is used to measure the fuel le-
ver in the float chamber.

2-23
SPEC
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS ................................................................. 2-1
ENGINE SPECIFICATIONS ..................................................................... 2-2
CHASSIS SPECIFICATIONS ................................................................... 2-6
ELECTRICAL SPECIFICATIONS ............................................................ 2-9
CONVERTION TABLE ............................................................................ 2-12
GENERAL TIGHTENING TORQUE SPECIFICATIONS ....................... 2-12
TIGHTENING TORQUES........................................................................ 2-13
ENGINE ............................................................................................ 2-13
CHASSIS.......................................................................................... 2-14
LUBRICATION POINTS AND LUBRICANT TYPES............................. 2-16
ENGINE ............................................................................................ 2-16
CHASSIS.......................................................................................... 2-17
CABLE ROUTING .................................................................................. 2-18

2-1
SPEC
SPECIFICATIONS
GENERAL SPECIFICATIONS
Item Standard Limit
GENERAL SPECIFICATIONS
Model
Code 5PJ5 (USA) …
5PN6 (CAN) …
Dimensions
Overall length 1890mm (74.41in) …
Overall width 705mm (27.76in) …
Overall height 1110mm (43.70in) …
Seat height 765mm (30.12in) …
Wheelbase 1275mm (50.20in) …
Minimum ground clearance 120mm (4.72in) …
Minimum turning radius 1800mm (70.87in) …
Weight
Wet (without oil and a full fuel tank) 94kg (207lb) …
Dry (without oil and fuel) 90kg (198lb) …
Maximun load (total of cargo, rider, 143kg (315lb) …
passenger, and accessories)

2-2
SPEC
Engine
Engine type Air-cooled 2-stroke reed valve …
Displacement 0.049L (49cm³, 2.99cu-in) …
Cylinder arrangement Forward inclined single cylinder …
Bore × stroke 40.0 × 39.2mm (1.57 × 1.54in) …
Compression ratio 7.01:1 …
Engine idle speed 1800 ~ 1900r/min …
Fuel
Recommended fuel Unleaded gasoline only (USA) …
Regular unleaded gasoline …
only (CAN)
Fuel tank capacity
Total 5.7L (1.25 Imp gal, 1.50 US gal) …
Engine oil
Lubrication system Separate lubrication …
Recommended oil YAMALUBE 2 or air cooled …
2-stroke engine oil
Quantity
Oil tank 1.4L (1.23 Imp qt, 1.48 US qt) …
Final gear oil
Recommended oil SAE85W140 hypoid gear oil …
Periodic oil change 0.11L (0.10 Imp qt, 0.12 US qt) …
Total amount 0.13L (0.12 Imp qt, 0.14 US qt) …
Air filter
Air filter type Wet element …
Starting system type Electric and kick starter …
Carburetor
Type Y14P-13E …
Manufacturer TEIKEI …
Spark plug
Model (manufacturer) × quantity BPR7HS (NGK ) × 1 …
Spark plug gap 0.6 ~ 0.7mm (0.024 ~ 0.028in) …
Cylinder head
Volume 5.54 ~ 5.84cm³ …
(0.34 ~ 0.36cu-in)
Maximum warpage … 0.05mm
(0.0020in)
* Lines indicate straighedge measurement
ENGINE SPECIFICATIONS
Item Standard Limit
ENGINE SPECIFICATIONS

2-3
SPEC
Item Standard Limit
ENGINE SPECIFICATIONS
Cylinder
Bore 40.000 ~ 40.014mm …
(1.5748 ~ 1.5754in)
Maximum taper … 0.05mm
(0.0020in)
Maximum out-of-round … 0.05mm
(0.0020in)
Piston
Piston-to-cylinder clearance 0.035 ~ 0.040mm 0.10mm
(0.0014 ~ 0.0016in) (0.0039in)
Diameter D 39.960 ~ 39.979mm …
(1.5732 ~ 1.5739in)
Height H 5.0mm (0.1969in) …
Piston pin bore (in the piston)
Diameter 10.004 ~ 10.015mm 10.045mm
(0.3939 ~ 0.3943in) (0.3955in)
Piston pin
Outside diameter 9.996 ~ 10.000mm 9.976mm
(0.3935 ~ 0.3937in) (0.3928in)
Piston rings
Section sketch (B × T)/type
Top ring 1.2 × 1.6mm/keystone …
(0.0472 × 0.0630in)
2nd ring 1.2 × 1.6mm/keystone …
(0.0472 × 0.0630in)
End gap (installed)
Top ring 0.15 ~ 0.35mm 0.6mm
(0.0059 ~ 0.0138in) (0.0236in)
2nd ring 0.15 ~ 0.35mm 0.7mm
(0.0059 ~ 0.0138in) (0.0276in)
Side clearance (installed)
Top ring 0.03 ~ 0.05mm 0.1mm
(0.0012 ~ 0.0020in) (0.0039in)
2nd ring 0.03 ~ 0.05mm 0.11mm
(0.0012 ~ 0.0020in) (0.0043in)
Connecting rod
Connecting rod length 79.9~80.1mm …
(3.1457~3.1535in)
Small end inside diameter 13.996~14.007mm …
(0.5510~0.5515in)
H
D

2-4
SPEC
Item Standard Limit
Crankshaft
Width “A” 37.90 ~ 37.95mm …
(1.4921 ~ 1.4941in)
Maximum runout “C” … 0.03mm
(0.0012in)
Big end side clearance “D” 0.20 ~ 0.50mm 1.00mm
(0.0079 ~ 0.0197in) (0.0394in)
Big end radial clearance 0.004 ~ 0.017mm …
(0.0002 ~ 0.0007in)
Small end free play “F” 0.40 ~ 0.80mm …
(0.0157 ~ 0.0315in)
Clutch
Clutch type Automatic centrifugal …
Clutch shoe thickness 2.5mm (0.10in) 1.0mm
(0.04in)
Clutch shoe spring free length 26.2mm (1.03in) …
Clutch housing inside diameter 105mm (4.13in) 105.5mm
(4.15in)
Compression spring free length 65.1mm (2.56in) 61.8mm
(2.43in)
Weight outside diameter 15.0mm (0.59in) 14.5mm
(0.57in)
Clutch - in revolution 2800 ~ 3200r/min …
Clutch - stall revolution 4500 ~ 5500r/min …
V-belt
V-belt width 16.5mm (0.65in) 14.8mm
(0.58in)
Kickstarter
Type Ratchet …
Kick clip tension 0.7 ~ 2N (0.07 ~ 0.2kgf) …
(0.15 ~ 0.44lb)
Transmission
Transmission type V-belt automatic …
Primary reduction system Helical gear …
Primary reduction ratio 52/13 (4.000) …
Secondary reduction system Super gear …
Secondary reduction ratio 43/13(3.307) …
Single speed automatic 2.693 ~ 0.889:1 …
Maximum main axle runout … 0.02mm
(0.0008in)
Maximum drive axle runout … 0.02mm
(0.0008in)
ENGINE SPECIFICATIONS

2-5
SPEC
Item Standard Limit
ENGINE SPECIFICATIONS
Carburetor
ID mark 5PJ5 00 …
Main jet (M.J.) # 80 …
Needle jet (N.J.) 2.085 …
Jet needle-clip position (J.N.) 3N24-1/1 …
Main air jet (M.A.J.) 2.0 …
Cutaway (C.A.) 3.0 …
Pilot jet (P.J.) # 44 …
Bypass 0.8 …
Valve seat size (V.S.) 1.8 …
Starter jet (St.J.) 0.45 …
Float height 15 ~ 17mm (0.59 ~ 0.67in) …
Fuel level height 3.0 ~ 4.0mm (0.12 ~ 0.16in) …
Engine idle speed 1800 ~ 1900r/min …
Reed valve
Thickness 0.132 ~ 0.172mm
(0.0052 ~ 0.0068in) …
Valve stopper height 5.9 ~ 6.5mm (0.23 ~ 0.26in) …
Valve bending limit … 0.2mm
(0.0078in)