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 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