
SERVICE MANUAL
RS90K
RS90RK
RSG90K
RS90MK
RST90K
RST90TFK
LIT-12618-02-38 8FJ-28197-10
981096

NOTICE
This manual was written by the Yamaha Motor
Company primarily for use by Yamaha dealers and
their qualified mechanics. It is not possible to put an
entire mechanic’s education into one manual, so it
is assumed that persons using this book to perform
maintenance and repairs on Yamaha snowmobiles
have a basic understanding of the mechanical con-
cepts and procedures inherent in snowmobile
repair. Without such knowledge, attempted repairs
or service to this model may render it unfit and/or
unsafe to use. Yamaha Motor Company, Ltd. is
continually striving to improve all models manufac-
tured by Yamaha. Modifications and significant
changes in specifications or procedures will be for-
warded to all authorized Yamaha dealers and will,
where applicable, appear in future editions of this
manual.
HOW TO USE THIS MANUAL
Particularly important information is distinguished in
this manual by the following notations:
The Safety Alert Symbol means ATTENTION! BE
ALERT! YOUR SAFETY IS INVOLVED!
Failure to follow WARNING instructions could result
in severe injury or death to the snowmobile opera-
tor, a bystander, or a person inspecting or repairing
the snowmobile.
A CAUTION indicates special precautions that
must be taken to avoid damage to the snowmobile.
A NOTE provides key information that can make
procedures easier or clearer.
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 inspection,
repair, assembly, and disassembly operations.
In this revised format, the condition of a faulty com-
ponent will precede an arrow symbol and the
course of action required to correct the problem will
follow the symbol, e.g.,
• Bearings
Pitting/damage → Replace.
EXPLODED DIAGRAM
Each chapter provides exploded diagrams before
each disassembly section to facilitate correct disas-
sembly and assembly procedures.
RS90K, RS90RK, RSG90K,
RS90MK, RST90K, RST90TFK
SERVICE MANUAL
©2004 by Yamaha Motor
Corporation, U.S.A.
1st Edition, May 2004
All rights reserved. Any reprinting or
unauthorized use without the written
permission of Yamaha Motor Corporation,
U.S.A. is expressly prohibited.
Printed in U.S.A.
P/N.LIT-12618-02-38
WARNING
CAUTION:
NOTE:

ILLUSTRATED SYMBOLS
(Refer to the illustration)
Illustrated symbols 1 to 9 are designed as thumb
tabs to indicate the chapter’s number and content.
1 General information
2 Periodic inspection and adjustment
3 Chassis
4 Power train
5 Engine
6 Cooling system
7 Carburetion
8 Electrical
9 Specifications
Illustrated symbols 0 to F are used to identify the
specifications which appear.
0 Filling fluid
A Lubricant
B Tightening
C Wear limit, clearance
D Engine speed
E Special tool
F Ω, V, A
Illustrated symbols G to O in the exploded diagram
indicate grade of lubricant and location of lubrica-
tion point.
G Apply locking agent (LOCTITE
®
)
H Apply Yamabond No.5
®
I Apply engine oil
J Apply gear oil
K Apply molybdenum disulfide oil
L Apply wheel bearing grease
M Apply low-temperature lithium-soap base grease
N Apply molybdenum disulfide grease
O Use new one
1 2
3 4
5 6
7 8
9
0 A B
C D E
F G H
I J K
L M N
O
GEN
INFO
INSP
ADJ
CHAS
POWR
TR
ENG
COOL
CARB
– +
ELEC
SPEC
T
R
.
.
LT
5
E G M
B LS M
New

INDEX
GENERAL INFORMATION
GEN
INFO 1
PERIODIC INSPECTION AND
ADJUSTMENT
INSP
ADJ
2
CHASSIS
CHAS
3
POWER TRAIN
POWR
TR 4
ENGINE
ENG
5
COOLING SYSTEM
COOL
6
CARBURETION
CARB
7
ELECTRICAL
ELEC
8
SPECIFICATIONS
SPEC
9
– +

CHAPTER 1.
GENERAL INFORMATION
MACHINE IDENTIFICATION............................ 1-1
FRAME SERIAL NUMBER ......................... 1-1
ENGINE SERIAL NUMBER ........................ 1-1
IMPORTANT INFORMATION .......................... 1-2
PREPARATION FOR REMOVAL AND
DISASSEMBLY........................................... 1-2
ALL REPLACEMENT PARTS..................... 1-2
GASKETS, OIL SEALS, AND O-RINGS..... 1-3
LOCK WASHERS/PLATES
AND COTTER PINS ................................... 1-3
BEARINGS AND OIL SEALS ..................... 1-3
CIRCLIPS ................................................... 1-3
LOCTITE
®
.................................................. 1-3
SPECIAL TOOLS ............................................. 1-4
FOR TUNE UP............................................ 1-4
FOR ENGINE SERVICE ............................. 1-4
FOR POWER TRAIN SERVICE ................. 1-7
FOR CARBURETION SERVICE ................ 1-8
FOR ELECTRICAL SERVICE .................... 1-8
CHAPTER 2.
PERIODIC INSPECTION AND
ADJUSTMENT
INTRODUCTION............................................... 2-1
PERIODIC MAINTENANCE CHART................ 2-1
ENGINE ............................................................ 2-3
SPARK PLUGS........................................... 2-3
FUEL LINE INSPECTION ........................... 2-3
COOLING SYSTEM.................................... 2-4
VALVE CLEARANCE ADJUSTMENT ........ 2-7
CARBURETOR SYNCHRONIZATION ..... 2-13
ENGINE IDLE SPEED ADJUSTMENT ..... 2-14
THROTTLE CABLE FREE PLAY
ADJUSTMENT .......................................... 2-15
THROTTLE OVERRIDE SYSTEM
(T.O.R.S.) CHECK .................................... 2-16
COMPRESSION PRESSURE
MEASUREMENT ...................................... 2-17
ENGINE OIL LEVEL INSPECTION .......... 2-18
ENGINE OIL REPLACEMENT ................. 2-20
CRANKCASE BREATHER HOSE
INSPECTION ............................................ 2-23
CARBURETOR JOINTS INSPECTION .... 2-23
CHECKING THE AIR FILTER
ELEMENT ................................................. 2-23
EXHAUST SYSTEM INSPECTION .......... 2-24
POWER TRAIN............................................... 2-25
SHEAVE OFFSET ADJUSTMENT ........... 2-25
DRIVE V-BELT.......................................... 2-27
ENGAGEMENT SPEED CHECK .............. 2-29
PARKING BRAKE ADJUSTMENT............ 2-30
BRAKE FLUID LEVEL INSPECTION ....... 2-30
BRAKE PAD INSPECTION....................... 2-31
BRAKE HOSE INSPECTION .................... 2-31
AIR BLEEDING (HYDRAULIC BRAKE
SYSTEM) .................................................. 2-32
DRIVE CHAIN ........................................... 2-33
TRACK TENSION ADJUSTMENT ............ 2-35
SLIDE RUNNER INSPECTION ................ 2-37
MAXIMIZING DRIVE TRACK LIFE ........... 2-37
CHASSIS ........................................................ 2-39
SKI/SKI RUNNER ..................................... 2-39
STEERING SYSTEM ................................ 2-40
LUBRICATION .......................................... 2-41
ELECTRICAL ................................................. 2-44
HEADLIGHT BEAM ADJUSTMENT ......... 2-44
BATTERY INSPECTION........................... 2-44
FUSE INSPECTION.................................. 2-52
SPEEDOMETER UNIT INSPECTION ...... 2-54
TUNING .......................................................... 2-55
CARBURETOR TUNING .......................... 2-55
CLUTCH.................................................... 2-62
GEAR SELECTION................................... 2-67
HIGH ALTITUDE TUNING ........................ 2-73
FRONT SUSPENSION ............................. 2-74
REAR SUSPENSION................................ 2-75
CHAPTER 3.
CHASSIS
STEERING ........................................................ 3-1
RS90/RS90R/RSG90/RST90/RST90TF ..... 3-1
RS90M ........................................................ 3-3
REMOVAL................................................... 3-7
INSPECTION .............................................. 3-7
INSTALLATION........................................... 3-8
SKI .................................................................. 3-12
RS90/RS90R/RSG90 “USA/Canada” ....... 3-12
RSG90 “Europe”/RST90 “Europe”/
RST90TF................................................... 3-13
RS90M ...................................................... 3-14
RST90 “USA/Canada”............................... 3-15
INSPECTION ............................................ 3-16
INSTALLATION
(RST90 “USA/Canada”) ............................ 3-17

FRONT SUSPENSION ................................... 3-18
HANDLING NOTES .................................. 3-20
INSPECTION ............................................ 3-20
INSTALLATION ........................................ 3-21
CHAPTER 4.
POWER TRAIN
PRIMARY SHEAVE AND DRIVE V-BELT ....... 4-1
REMOVAL .................................................. 4-3
DISASSEMBLY........................................... 4-3
INSPECTION .............................................. 4-4
ASSEMBLY................................................. 4-6
INSTALLATION .......................................... 4-9
SECONDARY SHEAVE ................................. 4-10
DISASSEMBLY......................................... 4-12
INSPECTION ............................................ 4-12
ASSEMBLY............................................... 4-13
INSTALLATION ........................................ 4-15
DRIVE CHAIN HOUSING ............................... 4-16
WITHOUT REVERSE MODEL ................. 4-16
REMOVAL ................................................ 4-18
INSPECTION ............................................ 4-18
INSTALLATION ........................................ 4-20
WITH REVERSE MODEL ......................... 4-21
REMOVAL ................................................ 4-24
INSPECTION ............................................ 4-24
INSTALLATION ........................................ 4-25
SECONDARY SHAFT .................................... 4-27
REMOVAL ................................................ 4-28
INSPECTION ............................................ 4-29
INSTALLATION ........................................ 4-29
SECONDARY SHAFT AND DRIVE CHAIN
HOUSING INSTALLATION....................... 4-32
BRAKE ........................................................... 4-34
BRAKE PAD REPLACEMENT ................. 4-35
BRAKE CALIPER DISASSEMBLY ........... 4-38
BRAKE CALIPER INSPECTION
AND REPAIR ............................................ 4-38
BRAKE CALIPER ASSEMBLY ................. 4-39
BRAKE CALIPER INSTALLATION ........... 4-39
INSPECTION ............................................ 4-41
BRAKE MASTER CYLINDER
ASSEMBLY............................................... 4-41
INSTALLATION ........................................ 4-41
SLIDE RAIL SUSPENSION............................ 4-42
RS90/RS90R............................................. 4-42
RSG90 ...................................................... 4-48
RS90M ...................................................... 4-53
RST90 ....................................................... 4-59
RST90TF................................................... 4-65
REMOVAL................................................. 4-72
INSPECTION ............................................ 4-72
ASSEMBLY ............................................... 4-73
INSTALLATION......................................... 4-75
FRONT AXLE AND TRACK ........................... 4-78
INSPECTION ............................................ 4-79
INSTALLATION......................................... 4-79
CHAPTER 5.
ENGINE
SEAT AND FUEL TANK................................... 5-1
RS90/RS90R/RSG90/RS90M..................... 5-1
BACKREST AND PASSENGER SEAT ........... 5-2
RST90/RST90TF ........................................ 5-2
RIDER SEAT AND FUEL TANK ...................... 5-3
RST90/RST90TF ........................................ 5-3
REMOVAL................................................... 5-4
INSTALLATION........................................... 5-4
OIL TANK ......................................................... 5-5
ENGINE ASSEMBLY ....................................... 5-6
HOSE AND LEADS..................................... 5-6
ENGINE ASSEMBLY .................................. 5-8
REMOVAL................................................... 5-9
INSTALLATION........................................... 5-9
EXHAUST PIPE AND MUFFLER ................... 5-11
INSTALLATION......................................... 5-12
CAMSHAFTS.................................................. 5-14
CYLINDER HEAD COVER ....................... 5-14
CAMSHAFTS ............................................ 5-15
REMOVAL................................................. 5-16
INSPECTION ............................................ 5-17
INSTALLATION......................................... 5-20
CYLINDER HEAD........................................... 5-24
REMOVAL................................................. 5-25
INSPECTION ............................................ 5-25
INSTALLATION......................................... 5-26
VALVES AND VALVE SPRINGS ................... 5-28
REMOVAL................................................. 5-29
INSPECTION ............................................ 5-30
INSTALLATION......................................... 5-34

A.C. MAGNETO ROTOR
AND STARTER CLUTCH............................... 5-37
REMOVAL ................................................ 5-38
INSPECTION ............................................ 5-39
INSTALLATION ........................................ 5-40
OIL PAN AND OIL PUMP .............................. 5-42
REMOVAL ................................................ 5-45
INSPECTION ............................................ 5-45
INSTALLATION ........................................ 5-47
CRANKCASE ................................................. 5-49
CRANKCASE............................................ 5-49
CONNECTING RODS AND PISTONS ..... 5-51
CRANKSHAFT
AND BALANCER SHAFT ......................... 5-52
REMOVAL ................................................ 5-54
INSPECTION ............................................ 5-56
INSTALLATION ........................................ 5-67
CHAPTER 6.
COOLING SYSTEM
HEAT EXCHANGER ........................................ 6-1
INSPECTION .............................................. 6-4
INSTALLATION .......................................... 6-5
THERMOSTAT ................................................. 6-6
INSPECTION .............................................. 6-7
INSTALLATION .......................................... 6-7
WATER PUMP.................................................. 6-9
REMOVAL ................................................ 6-11
DISASSEMBLY......................................... 6-11
INSPECTION ............................................ 6-12
ASSEMBLY............................................... 6-12
INSTALLATION ........................................ 6-13
CHAPTER 7.
CARBURETION
CARBURETORS AND FUEL PUMP................ 7-1
INSPECTION .............................................. 7-6
ASSEMBLY................................................. 7-8
INSTALLATION .......................................... 7-9
FUEL LEVEL ADJUSTMENT ................... 7-10
THROTTLE POSITION SENSOR (T.P.S.)
INSPECTION AND ADJUSTMENT .......... 7-11
INSPECTION ............................................ 7-12
INSTALLATION ........................................ 7-13
CHAPTER 8.
ELECTRICAL
SWITCH INSPECTION ..................................... 8-1
SWITCH INSPECTION ............................... 8-1
INSPECTING A SWITCH SHOWN
IN THE MANUAL ........................................ 8-1
IGNITION SYSTEM .......................................... 8-2
CIRCUIT DIAGRAM.................................... 8-2
TROUBLESHOOTING ................................ 8-4
IGNITION SPARK GAP .............................. 8-6
IGNITION COIL ........................................... 8-6
PICKUP COIL ............................................. 8-7
THROTTLE OVERRIDE SYSTEM
(T.O.R.S.) .................................................... 8-8
ENGINE STOP SWITCH ............................ 8-8
THROTTLE SWITCH .................................. 8-9
MAIN SWITCH ............................................ 8-9
ELECTRICAL STARTING SYSTEM .............. 8-10
CIRCUIT DIAGRAM.................................. 8-10
TROUBLESHOOTING .............................. 8-11
STARTER MOTOR ................................... 8-13
CHARGING SYSTEM ..................................... 8-18
CIRCUIT DIAGRAM.................................. 8-18
TROUBLESHOOTING .............................. 8-19
BATTERY.................................................. 8-20
A.C. MAGNETO ........................................ 8-20
LIGHTING SYSTEM ....................................... 8-22
CIRCUIT DIAGRAM.................................. 8-22
TROUBLESHOOTING .............................. 8-24
BULB(S) .................................................... 8-26
HEADLIGHT BEAM SWITCH ................... 8-26
HEADLIGHT RELAY ................................. 8-26
LOAD CONTROL RELAY ......................... 8-27
SIGNAL SYSTEM ........................................... 8-28
CIRCUIT DIAGRAM.................................. 8-28
TROUBLESHOOTING .............................. 8-30
BRAKE LIGHT SWITCH ........................... 8-36
GEAR POSITION SWITCH
(RS90R/RSG90/RST90/RST90TF)........... 8-36
DC BACK BUZZER
(RS90R/RSG90/RST90/RST90TF)........... 8-36
COOLANT TEMPERATURE SENSOR .... 8-37
OIL LEVEL SWITCH ................................. 8-38
FUEL SENDER ......................................... 8-38
SPEED SENSOR ...................................... 8-39

GRIP WARMER SYSTEM .............................. 8-40
CIRCUIT DIAGRAM.................................. 8-40
TROUBLESHOOTING .............................. 8-42
GRIP AND THUMB WARMER COIL ........ 8-44
THUMB WARMER ADJUSTMENT
SWITCH .................................................... 8-44
GRIP WARMER ADJUSTMENT
SWITCH .................................................... 8-45
PASSENGER GRIP WARMER
(RST90/RST90TF) .................................... 8-45
PASSENGER GRIP WARMER SWITCH
(RST90/RST90TF) .................................... 8-46
PASSENGER GRIP WARMER RELAY
(RST90/RST90TF) .................................... 8-46
CARBURETOR HEATER SYSTEM ............... 8-48
CIRCUIT DIAGRAM.................................. 8-48
TROUBLESHOOTING .............................. 8-50
CARBURETOR HEATER RELAY ............ 8-51
CARBURETOR HEATER ......................... 8-51
SELF-DIAGNOSIS.......................................... 8-52
SELF-DIAGNOSIS CODE ........................ 8-53
CHAPTER 9.
SPECIFICATIONS
GENERAL SPECIFICATIONS ......................... 9-1
MAINTENANCE SPECIFICATIONS ................ 9-4
ENGINE ...................................................... 9-4
POWER TRAIN........................................... 9-9
CHASSIS .................................................. 9-15
ELECTRICAL ............................................ 9-17
HIGH ALTITUDE SETTINGS.................... 9-19
TIGHTENING TORQUE.................................. 9-20
ENGINE .................................................... 9-20
POWER TRAIN......................................... 9-22
CHASSIS .................................................. 9-25
GENERAL TORQUE SPECIFICATIONS ....... 9-26
DEFINITION OF UNITS .................................. 9-26
CABLE ROUTING .......................................... 9-28

1-1
GEN
INFO
GENERAL INFORMATION
MACHINE IDENTIFICATION
FRAME SERIAL NUMBER
The frame serial number 1 is located on the right-hand side of the frame
(just below the front of the seat).
1
ENGINE SERIAL NUMBER
The engine serial number 1 is located on the right-hand side of the crank-
case.
NOTE:
Designs and specifications are subject to change without notice.
1
MACHINE IDENTIFICATION

1-2
GEN
INFO
IMPORTANT INFORMATION
IMPORTANT INFORMATION
PREPARATION FOR REMOVAL AND DISASSEMBLY
1.Remove all dirt, mud, dust, and foreign material before removal and
disassembly.
While cleaning, take care to protect the electrical parts, such as relays,
switches, motor, resistors, controllers, etc., from high pressure water
splashes.
2. Use proper tools and cleaning equipment.
Refer to “SPECIAL TOOLS”.
3.When disassembling the machine, keep mated parts together. This
includes gears, cylinders, pistons, and other parts that have been
“mated” through normal wear. Mated parts must be reused or replaced
as an assembly.
4. During disassembly of the machine, clean all parts and place them in
trays in the order of disassembly. This will speed up assembly time and
help ensure that all parts are reinstalled correctly.
5.Keep all parts away from any source of fire.
6.Be sure to keep to the tightening torque specifications. When tighten-
ing bolts, nuts, and screws, start with those that have larger diameters,
and proceed from the inside to the outside in a crisscross pattern.
ALL REPLACEMENT PARTS
We recommend using genuine Yamaha parts for all replacements. Use oil
and grease recommended by Yamaha for assembly and adjustments.
1
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2008 Yamaha RS VECTOR / GT / LTX / LTX GT Snowmobile Service Manual
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Description
Get the 2008 Yamaha RS VECTOR / GT / LTX / LTX GT Snowmobile Service Manual for comprehensive, step-by-step procedures. This manual is designed to be an easy-to-read reference for mechanics, offering detailed explanations for disassembly, repair, assembly, and inspection operations. Each chapter includes exploded diagrams before the disassembly section, making it simple to identify the correct procedures.