Yamaha YZ85W1 User manual

2007
YZ85W1
5PA-28197-E0
SERVICE MANUAL
YZ85(W)
YZ85LW(W)

YZ85W1/YZ85 (W)/YZ85LW (W)
SERVICE MANUAL
©2006 by Yamaha Motor Co., Ltd.
First edition, April 2006
All rights reserved.
Any reproduction or unauthorized use
without the written permission of
Yamaha Motor Co., Ltd.
is expressly prohibited.
EAS00000

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 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 deal-
ers and will appear in future editions of this manual where applicable.
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Designs and specifications are subject to change without notice.
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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 vehicle operator, a bystander or a person checking or repairing the
vehicle.
A CAUTION indicates special precautions that must be taken to avoid dam-
age to the vehicle.
A NOTE provides key information to make procedures easier or clearer.
WARNING
CAUTION:
NOTE:

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 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,
except in Chapter 3 (“PERIODIC CHECKS AND ADJUSTMENTS”), where the sub-section title(s)
appears.
Sub-section titles appear in smaller print than the section title.
To help identify parts and clarify procedure steps, there are exploded diagrams at the start of
each removal and disassembly section.
Numbers are given in the order of the jobs in the exploded diagram. A circled number indicates a
disassembly step.
Symbols indicate parts to be lubricated or replaced.
Refer to “SYMBOLS”.
A job instruction chart accompanies the exploded diagram, providing the order of jobs, names of
parts, notes in jobs, etc.
Jobs requiring more information (such as special tools and technical data) are described sequen-
tially.

EAS00008
SYMBOLS
The following symbols are not relevant to every
vehicle.
Symbols to indicate the subject of each
chapter.
General information
Specifications
Periodic checks and adjustments
Chassis
Engine
Cooling system
Carburetor(s)
Electrical system
Tuning
Troubleshooting
Symbols to indicate the following.
Serviceable with engine mounted
Filling fluid
Lubricant
Special tool
Tightening torque
Wear limit, clearance
Engine speed
Electrical data
Symbols to in the exploded diagrams
indicate the types of lubricants and lubrication
points.
Engine oil
Gear oil
Molybdenum-disulfide oil
Wheel-bearing grease
Lithium-soap- based grease
Molybdenum-disulfide grease
Symbols to in the exploded diagrams
indicate the following.
Apply locking agent (LOCTITE®)
Replace the part with a new one.

EAS00010
TABLE OF CONTENTS
GENERAL INFORMATION GEN
INFO 1
SPECIFICATIONS SPEC 2
PERIODIC CHECKS AND
ADJUSTMENTS CHK
ADJ 3
CHASSIS CHAS 4
ENGINE ENG 5
COOLING SYSTEM COOL 6
CARBURETOR CARB 7
ELECTRICAL SYSTEM ELEC 8
TUNING TUN 9
TROUBLESHOOTING TRBL
SHTG 10

GEN
INFO
CHAPTER 1
GENERAL INFORMATION
VEHICLE 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
FUEL AND ENGINE MIXING OIL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
CHECKING THE CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
SPECIAL TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

GEN
INFO
1-1
EAS00014
GENERAL INFORMATION
VEHICLE IDENTIFICATION
EAS00017
VEHICLE IDENTIFICATION NUMBER
The vehicle identification number is
stamped into the right side of the steering
head pipe.
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MODEL LABEL
The model label is affixed to the frame. This
information will be needed to order spare
parts.
VEHICLE IDENTIFICATION

GEN
INFO
1-2
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 replace-
ments. Use oil and grease recommended 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.
lip
oil
lip
spring
grease
IMPORTANT INFORMATION

GEN
INFO
1-3
EAS00023
LOCK WASHERS/PLATES AND COTTER
PINS
After removal, replace all lock washers/plates
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.
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.
Oil seal
CAUTION:
Do not spin the bearing with compressed
air because this will damage the bearing
surfaces.
Bearing
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 , make sure the
sharp-edged corner is positioned opposite
the thrust that the circlip receives.
Shaft
IMPORTANT INFORMATION

GEN
INFO
1-4
FUEL AND ENGINE MIXING OIL
Mix oil with the gas at the ratio specified below.
Always use fresh, name-brand gasoline, and
mix the oil and gas the day of the race. Do not
use premix that is more than a few hours old.
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If knocking or pinging occurs, use a different
brand of gasoline or higher octane grade.
CAUTION:
Never mix two types of oil in the same
batch; clotting of the oil could result. If you
wish to change oil types, be sure to drain
the fuel tank and the carburetor float bowl
of old premix prior to filling with the new
type.
Recommended fuel
Premium unleaded gasoline
only with a research octane
number of 95 or higher.
Fuel tank capacity
5.0 L (1.10 Imp gal, 1.32 US gal)
Mixing oil
Recommended oil
Yamalube “2-R”
(Yamalube racing 2-cycle oil)
Mixing ratio: 30 : 1
If unavailable, use an equivalent
type of oil.
YAMALUBE “2-R”
FUEL AND ENGINE MIXING OIL

GEN
INFO
1-5
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.
3. Check:
• all connections
Loose connection →Connect properly.
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If the pin on the terminal is flattened, bend it
up.
4. Connect:
• lead
• coupler
• connector
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Make sure all connections are tight.
5. Check:
• continuity
(with the pocket tester)
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• 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, YU-3112-C
CHECKING THE CONNECTIONS

GEN
INFO
1-6
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.
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• For U.S.A. and Canada, use part number starting with “YM-”, “YU-”, or “ACC-”.
• For others, use part number starting with “90890-”.
Tool No. Tool name/Function Illustration
90890-01135
YU-1135-A
Crankcase separating tool
This tool is used to split the crankcase as well
as remove the crankshaft from either case.
90890-01189
YM-1189
Flywheel puller
This tool is used to remove the flywheel
magneto.
90890-01235
YU-1235
Rotor holding tool
This tool is used when loosening or tightening
the flywheel magneto securing nut.
Dial gauge set
90890-01252
Dial gauge and
stand
YU-3097
YU-1256
Dial gauge and stand
Stand
These tools are used to check each part for
runout or bent.
90890-01268
Ringnut wrench
This tool is used to loosen and tighten the
exhaust and steering ringnut.
Crankshaft installing tool
For EUR, OCE
90890-01274
90890-01275
90890-01277
For U.S.A, CAN
YU-90050
YM-1277
Crankshaft installing tool
Crankshaft installing pot
Crankshaft installing bolt
Adapter (M10)
These tools are used to install the crankshaft.
90890-01304
YU-1304
Piston pin puller set
This tool is used to remove the piston pin.
SPECIAL TOOLS

GEN
INFO
1-7
Tool No. Tool name/Function Illustration
Radiator cap tester
90890-01325
YU-24460-01
Radiator cap
tester adapter
90890-01352
YU-33984
Radiator cap tester
Radiator cap tester adapter
These tools are used for checking the cooling
system.
90890-01403
YU-33975
Steering nut wrench
This tool is used when tighten the steering
ring nut to specification.
90890-01434
YM-01434
Rod holder
This tool is used to hold the fork spring.
Rod puller
90890-01437
YM-01437
Rod puller
attachment
90890-01436
YM-01436
Rod puller
Rod puller attachment (M10)
These tools are used to pull up the fork
damper rod.
90890-01442
YM-01442
Fork seal diver
This tool is used when install the fork oil seal.
90890-01454
YM-01454
Damper rod holder
Use this tool to remove and install the damper
rod.
90890-01495
YM-01495
Drive gear holder
This tool is used when removing or tightening
the primary drive gear securing nut.
90890-03112
YU-3112-C
Pocket tester
Use this tool to inspect the coil resistance,
output voltage and amperage.
90890-04086
YM-91042
Universal clutch holder
This tool is used to hold the clutch when
removing or installing the clutch boss
securing nut.
SPECIAL TOOLS

GEN
INFO
1-8
Tool No. Tool name/Function Illustration
90890-06754
YM-34487
Dynamic spark tester
Ignition checker
This instrument is necessary for checking the
ignition system components.
90890-85505
Yamaha bond No.1215
(Three Bond No.1215®)
This sealant (Bond) is used for crankcase
mating surface, etc.
SPECIAL TOOLS

SPEC
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
ENGINE SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
CHASSIS SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
ELECTRICAL SPECIFICATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
CONVERSION TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
GENERAL TIGHTENING TORQUE SPECIFICATIONS . . . . . . . . . . . . 2-12
TIGHTENING TORQUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
ENGINE TIGHTENING TORQUES . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
CHASSIS TIGHTENING TORQUES . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
LUBRICATION POINTS AND LUBRICANT TYPES . . . . . . . . . . . . . . . 2-16
ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
CHASSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
CABLE ROUTING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17

SPEC
2-1
SPECIFICATIONS
GENERAL SPECIFICATIONS
Item Standard Limit
Model code YZ85
5PAG (EUR, CAN), 5PAH (AUS,NZL) •••
YZ85LW
5SHG (EUR), 5SHH (AUS,NZL) •••
Dimensions
Overall length 1,818 mm (71.6 in) (YZ85) •••
1,903 mm (74.9 in) (YZ85LW) •••
Overall width 758 mm (29.8 in) •••
Overall height 1,161mm (45.7 in) (YZ85) •••
1,205 mm (47.4 in) (YZ85LW) •••
Seat height 864 mm (34.0 in) (YZ85) •••
904 mm (35.6 in) (YZ85LW) •••
Wheelbase 1,255 mm (49.4 in) (YZ85) •••
1,286 mm (50.6 in) (YZ85LW) •••
Minimum ground clearance 351 mm (13.8 in) (YZ85) •••
393 mm (15.5 in) (YZ85LW) •••
Dry weight
Without oil and fuel 66 kg (145.5 lb) (YZ85) •••
69 kg (152.2 lb) (YZ85LW) •••
GENERAL SPECIFICATIONS

SPEC
2-2
ENGINE SPECIFICATIONS
Item Standard Limit
Engine
Engine type Liquid cooled 2-stroke, gasoline •••
Displacement 84.7 cm3(5.17 cu.in) •••
Cylinder arrangement Single cylinder, forward inclined •••
Bore ×stroke 47.5 ×47.8 mm (1.870 ×1.882 in) •••
Compression ratio 8.2 : 1 •••
Fuel
Recommended fuel Premium unleaded gasoline only •••
Fuel tank capacity
Total 5.0L (1.09 Imp gal, 1.30 US gal) •••
Lubrication system Premix (30 : 1) (Yamalube 2-R) •••
Transmission oil
Recommended oil Yamalube 4 (10W-30) or SAE 10W-30 •••
API service SG type or higher
JASO standard MA
Periodic oil change 0.50 L (0.44 Imp qt, 0.53 US qt) •••
Total amount 0.55 L (0.48 Imp qt, 0.58 US qt) •••
Cooling system
Coolant capacity (including all routes) 0.54 L (0.48 Imp qt, 0.57 US qt) •••
Radiator capacity 0.32 L (0.28 Imp qt, 0.34 US qt) •••
Radiator cap opening pressure 93 ~ 123 kPa (0.93 ~ 1.23 kg/cm2,
13.2 ~ 17.5 psi)
•••
Radiator core
Width 117.8 mm (4.64 in) •••
Height 240.0 mm (9.45 in) •••
Depth 32.0 mm (1.26 in) •••
Water pump
Water pump type Single suction centrifugal pump •••
Reduction ratio 25/18 (1.388) •••
Starting system Kickstarter •••
Spark plug
Model (manufacturer) ×quantity BR10EG (NGK) × 1•
••
Spark plug gap 0.5 ~ 0.6 mm (0.0197 ~ 0.0236 in) •••
Cylinder head
Volume 7.14 cm3(0.44 cu.in) •••
Max. warpage ••• 0.03 mm
(0.0012 in)
ENGINE SPECIFICATIONS

SPEC
2-3
Item Standard Limit
Cylinder
Bore 47.500 ~ 47.514 mm (1.8701 ~ 1.8706 in) 47.6 mm
(1.874 in)
Max. taper limit ••• 0.05 mm
(0.0020 in)
Max. out-of-round ••• 0.01 mm
(0.0004 in)
Piston
Piston-to-cylinder clearance 0.040 ~ 0.045 mm (0.0016 ~ 0.0018 in) 0.1 mm
(0.004 in)
Diameter D 47.457 ~ 47.472 mm (1.8684 ~ 1.8690 in) 0.1 mm
(0.004 in)
Height H 20.0 mm (0.79 in) •••
Piston pin bore (in the piston)
Diameter 14.004 ~ 14.015 mm (0.5513 ~ 0.5518 in) 14.040 mm
(0.5528 in)
Offset 1.0 mm (0.039 in) •••
Offset direction Exhaust side •••
Piston pin
Outside diameter 13.996 ~ 14.000 mm (0.5510 ~ 0.5512 in) 13.975 mm
(0.5502 in)
Piston ring
Ring type Plain •••
Dimensions (B × T) 0.8 ×2.0 mm (0.032 ×0.079 in) •••
End gap (installed) 0.30 ~ 0.45 mm (0.012 ~ 0.018 in) 0.8 mm
(0.032 in)
Ring side clearance 0.030 ~ 0.065 mm (0.001 ~ 0.003 in) 0.1 mm
(0.004 in)
ENGINE SPECIFICATIONS

SPEC
2-4
Item Standard Limit
Crankshaft
Crank width “A” 44.90 ~ 44.95 mm (1.768 ~ 1.770 in) •••
Runout limit “C” 0.03 mm (0.0012 in) 0.05 mm
(0.002 in)
(YZ85)
0.08 mm
(0.003 in)
(YZ85LW)
Big end side clearance “D” 0.20 ~ 0.70 mm (0.008 ~ 0.028 in) •••
Small end free play “F” 0.5 ~ 1.2 mm (0.020 ~ 0.047 in) 2.0 mm
(0.08 in)
Clutch
Clutch type Wet, multiple disc •••
Clutch release method Inner push, cam push •••
Clutch cable free play (at the end of
the clutch lever)
10.0 ~ 15.0 mm (0.39 ~ 0.59 in) •••
Friction plates •••
Thickness 2.9 ~ 3.1 mm (0.114 ~ 0.122 in) 2.7 mm
(0.106 in)
Plate quantity 7 •••
Clutch plates
Thickness 1.8 ~ 2.2 mm (0.071 ~ 0.087 in) •••
Plate quantity 6 •••
Max. warpage ••• 0.1 mm
(0.004 in)
Clutch springs
Free length 33.0 mm (1.30 in) 31.0 mm
(1.22 in)
Spring quantity 5 •••
Clutch housing thrust clearance 0.10 ~ 0.35 mm (0.0039 ~ 0.0138 in) •••
Clutch housing radial clearance 0.022 ~ 0.051 mm (0.0009 ~ 0.0020 in) •••
ENGINE SPECIFICATIONS