Yamaha Mio User manual

5TL-F8197-E0
MIO
SERVICE MANUAL

EAS00000
AL115
SERVICE MANUAL
©2003 by Yamaha Motor Co., Ltd.
First edition, July 2003
All rights reserved.
Any reproduction or unauthorized use
without the written permission of
Yamaha Motor Co., Ltd.
is expressly prohibited.

EAS00002
NOTICE
This manual was produced by the Yamaha Motor Company, Ltd. primarily for use by Yamaha deal-
ers 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 motorcycle. Repair and maintenance work attempted by anyone without this knowledge is likely
to render the motorcycle 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 deal-
ers and will appear in future editions of this manual where applicable.
NOTE:
_
Designs and specifications are subject to change without notice.
EAS00004
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 motorcycle operator, a bystander or a person checking or repairing the
motorcycle.
A CAUTION indicates special precautions that must be taken to avoid damage
to the motorcycle.
A NOTE provides key information to make procedures easier or clearer.
WARNING
CAUTION:
NOTE:

EASF0001
HOW TO USE THIS MANUAL
CONSTRUCTION OF THIS MANUAL
This manual consists of chapters for the main categories of subjects. (See “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 checks and adjustments” the 3rd title appears.)
3rd title 3: This is a final title.
MANUAL FORMAT
All of the procedures in this manual are organized in a sequential, step-by-step format. The informa-
tion has been compiled to provide the mechanic with an easy to read, handy reference that contains
comprehensive explanations of all disassembly, repair, assembly, and inspections.
A set of particularly important procedure 4is placed between a line of triangle “▲” with each proce-
dure preceded by alphabetical letters.
IMPORTANT FEATURES
• Data and a special too are framed in a box preceded by a relevant symbol 5.
• An encircled numeral 6indicates a part name, and an encircled alphabetical letter or an align-
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 the course of action required
the symbol 9.
EXPLODED DIAGRAMS
Each chapter provide exploded diagrams before each disassembly section for ease in identifying
correct disassembly and assembly prodedures.

EASF0002
SYMBOLS
The following symbols are not relevant to
every vehicle.
Symbols 1to 8indicate the subject of each
chapter.
1General information
2Specifications
3Periodic checks and adjustments
4Engine
5Carburetor
6Chassis
7Electrical system
8Troubleshooting
Symbols 9to Findicate the following.
9Serviceable with engine mounted
0Filling fluid
ALubricant
BSpecial tool
CTightening torque
DWear limit, clearance
EEngine speed
FElectrical data
Symbols Gto Lin the exploded diagrams
indicate the types of lubricants and lubrication
points.
GEngine oil
HGear oil
IMolybdenum-disulfide oil
JWheel-bearing grease
KLithium-soap-based grease
LMolybdenum-disulfide grease
Symbols Mto Nin the exploded diagrams
indicate the following.
MApply locking agent (LOCTITE®)
NReplace the part
12
34
56
78
90
AB
CD
EF
GHI
JKL
MN
GEN
INFO
SPEC
CHK
ADJ ENG
CARB CHAS
–+
ELEC TRBL
SHTG
T
R
.
.
EGM
BLS M
LT
New

EASF0003
TABLE OF CONTENTS
GENERAL INFORMATION GEN
INFO 1
SPECIFICATIONS SPEC 2
PERIODIC CHECKS AND
ADJUSTMENTS CHK
ADJ 3
ENGINE ENG 4
CARBURETOR CARB 5
CHASSIS CHAS 6
ELECTRICAL SYSTEM ELEC 7
TROUBLESHOOTING TRBL
SHTG 8
–+

GEN
INFO
CHAPTER 1
GENERAL INFORMATION
MOTORCYCLE IDENTIFICATION..................................................................1-1
VEHICLE IDENTIFICATION NUMBER .....................................................1-1
ENGINE SERIAL NUMBER ......................................................................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

GEN
INFO

1 - 1
GEN
INFO
MOTORCYCLE IDENTIFICATION
EAS00014
GENERAL INFORMATION
MOTORCYCLE IDENTIFICATION
EAS00017
VEHICLE IDENTIFICATION NUMBER
The vehicle identification number 1is
stamped into the frame.
ENGINE SERIAL NUMBER
The engine serial number 1is stamped into
the crankcase.
NOTE:
Designs and specifications are subject to
change without notice.

1 - 2
GEN
INFO
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 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
replacements. Use oil and grease recom-
mended by Yamaha for all lubrication jobs.
Other brands may be similar in function and
appearance, but inferior 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 manu-
facturer’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 appro-
priate.
1Oil seal
CAUTION:
_
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.
Always replace piston pin clips after one use.
When installing a circlip 1, make sure the
sharp-edged corner 2is positioned opposite
the thrust 3that 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:
•lead
•coupler
•connector
2. Check:
•lead
•coupler
•connector
Moisture →Dry with an air blower.
Rust/stains →Connect and disconnect sev-
eral times.
3. Check:
•all connections
Loose connection →Connect properly.
NOTE:
_
If the pin 1on 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)
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.
Pocket tester
90890-03112

1 - 5
GEN
INFO
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.
Tool No. Tool name/Usage Illustration
Weight
90890-01084
Slide hammer bolt
90890-01085
Weight
Slide hammer bolt
These tools are used when removing or
installing the rocker arm shafts.
90890-01184
Fork seal driver weight
This tool is used to installing the oil seal.
90890-01186
Fork seal driver attachment
This tool is used to installing the oil seal.
90890-01189
Flywheel puller
This tool is used for removing the A.C.
magneto rotor.
90890-01235
Rotor holding tool
This tool is used to hold the A.C. mag-
neto rotor when removing or installing
the A.C. magneto rotor nut.
Compressor
90890-01253
Attachment
90890-01243
Valve spring compressor
Valve spring compressor attachment
These tools are used when removing or
installing the valve and the valve spring.
90890-01268
Ring nut wrench
This tool is used to loosen and tighten
the steering ring nut.

1 - 6
GEN
INFO
SPECIAL TOOLS
90890-01311
Tappet adjusting tool
This tool is necessary for adjusting
valve clearance.
90890-01312
Fuel level gauge
This gauge is used to measure the fuel
level in the float chamber.
90890-01326
T-handle
This tool is used for holding the damper
rod holder when removing or installing
the damper rod holder.
90890-01337
Clutch spring holder
This tool is used to disassembly and
assembly the secondary sheave.
90890-01384
Oil seal guide
This tool is used to install oil seals.
90890-01403
Steering nut wrench
This tool is used to loosen and tighten
the steering ring nut.
90890-01493
Socket wrench
This tool is used to loosen and tighten
the clutch carrier locknut of the second-
ary sheave.
90890-01701
Sheave holder
This tool is used for holding the primary
sheave and secondary sheave.
Tool No. Tool name/Usage Illustration

1 - 7
GEN
INFO
SPECIAL TOOLS
90890-03081
Compression gauge
These tools are used to measure the
engine compression.
90890-03112
Pocket tester
These instruments are invaluable for
checking the electrical system.
90890-03113
Engine tachometer
This tool is needed for detecting engine
rpm.
90890-04097
Valve guide remover (ø5)
This tool is needed to remove and
install the valve guide.
90890-04098
Valve guide installer (ø5)
This tool is needed to install the valve
guide.
90890-04099
Valve guide reamer (ø5)
This tool is needed to rebore the new
valve guide.
90890-04101
Valve lapper
This tool is used for lapping the valve.
90890-06754
Ignition checker
This instrument is necessary for check-
ing the ignition system components.
Tool No. Tool name/Usage Illustration

1 - 8
GEN
INFO
SPECIAL TOOLS
90890-85505
Yamaha bond No. 1215
This sealant (bond) is used for crank-
case mating surface, etc.
Tool No. Tool name/Usage Illustration

SPEC
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS ........................................................................2-1
ENGINE SPECIFICATIONS ............................................................................2-2
CHASSIS SPECIFICATIONS ..........................................................................2-9
ELECTRICAL SPECIFICATIONS .................................................................2-12
CONVERSION TABLE ..................................................................................2-15
GENERAL TIGHTENING TORQUE SPECIFICATIONS...............................2-15
TIGHTENING TORQUES ..............................................................................2-16
ENGINE TIGHTENING TORQUES.........................................................2-16
CHASSIS TIGHTENING TORQUES.......................................................2-18
LUBRICATION POINTS AND LUBRICANT TYPES ....................................2-20
ENGINE LUBRICATION POINTS AND LUBRICANT TYPES ................2-20
CHASSIS LUBRICATION POINTS AND LUBRICANT TYPES ..............2-21
CABLE ROUTING .........................................................................................2-22

SPEC