1987-1997 Yamaha Big Bear 350 ATV Service & Repair Manual

YFM350FW LIT-11616-FM-37 Service Manual

.YAMAHA II iCI IIIII LIT -11616-06-01

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 machines have a basic understanding of the mechanical concepts and procedures inherent in machine repair tech- nology. Without such knowledge, attempted repairs or service to this model may render it unfit to use and/or unsafe. Yamaha Motor Company, Ltd. is continually striving to improve all models manufactured by Yamaha. Modifications and significant changes in specifications or procedures will be forwarded to all Autho- rized Yamaha dealers and will, where applicable, appear in future editions of this manual. TECHNICAL PUBLICATIONS SERVICE DIVISION MOTORCYCLE OPERATIONS YAMAHA MOTOR CO., LTD. HOW TO USE THIS MANUAL PARTICULARLY IMPORTANT INFORMATION This material is distinguished by the following notation. NOTE: A NOTE provides key information to make procedures easier or clearer. WARNING: A CAUTION indicates special procedures that must be followed to avoid damage to the machine. A WARNING indicates special procedures that must be followed to avoid injury to a machine operator or person inspecting or repairing the machine. MANUAL FORMAT All of the procedures in this manual are organized in a sequential, step-by-step format. The information has been compiled to provide the mechanic with an easy to read, handy reference that contains comprehensive explanations of all disassembly, repair, assembly, and inspection operations. In this revised format, the condition of a faulty component will precede an arrow symbol and the course of action required will follow the symbol, e.g., • Bearings Pitting/Damage ~ Replace. EXPLODED DIAGRAM Each chapter provides exploded diagrams before each disassembly section for ease in identifying correct disassembly and assembly procedures. YFM350FW (T-8) SERVICE MANUAL © 1990 by Yamaha Motor Corporation, U.S.A. 1st Edition, January 1990 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. PIN: LlT-11616-07-58

INDEX GENERAL INFORMATION PERIODIC INSPECTIONS AND ADJUSTMENTS ENGINE CARBURETION DRIVE TRAIN CHASSIS ELECTRICAL APPENDICES "- ENG .(D. DR IV iii ELEC ~, APPX

<D (j) 1fm!b1~1 I~I.I ® @ I ENG 1'-1 ~.I @ ® ~RBI f 1 I DRIV 1-1&-1 (j) ® FH~~I IE~ECI iii 1 @ @) ~ IAPPXI~'1 CO) ~ @ If] @ ~ ® § @ [mJ @ • @, @ • @~ ® ® @ _8 .... .--§l1 ~ ILLUSTRATED SYMBOLS (Refer to the illustration) Illustrated symbols CD to ® are designed as thumb tabs to indicate the chapter's number and content. <D General information <i) Periodic inspection and adjustment @ Engine ® Cooling system ® Carburetion ® Drive train (j) Chassis @ Electrical ® Appendices Illustrated symbols @ to @) are used to iden .. tify the specifications appearing. @ Filling fluid CO) Lubricant @Tightening @Wear limit, clearance ® Engine speed @n,V,A Illustrated symbols @ to @ in the exploded diagram indicate grade of lubricant and location of lubrication point. @ Apply locking agent (LOCTITE® ) @ Apply engine oil @ Apply gear oil @ Apply molybdenum disulfide oil ® Apply wheel bearing grease ® Apply lightweight lithium-soap base grease @ Apply molybdenum disulfide grease

CHAPTER 1. GENERAL INFORMATION MACHINE IDENTIFiCATION .................................... 1-1 VEHICLE IDENTIFICATION NUMBER ......................... 1-1 ENGINE SERIAL NUMBER .................................. 1-1 IMPORTANT INFORMATION .................................... 1-2 ALL REPLACEMENT PARTS ................................. 1-2 GASKETS, OIL SEALS, AND O-RINGS ........................ 1-2 LOCK WASHERS/PLATES AND COTTER PINS .................. 1-2 BEARINGS AND OIL SEALS ................................ 1-2 CI RCLIPS ................................................. 1-3 SPECIAL TOOLS .............................................. 1-3 FOR TUNE-UP ............................................. 1-3 FOR ENGINE SERViCE ..................................... 1-4 FOR MIDDLE GEAR SERViCE ............................... 1-7 FOR FINAL GEAR SERVICE .................................. 1-8 FOR DIFFERENTIAL GEAR SERVICE ......................... • 1-8 FOR CHASSIS SERVICE ....................... • ............. • 1-9 FOR ELECTRICAL COMPONENTS ............................. 1-9

I~l-'bl'-'I MACHINE IDENTIFICATION ,-, GENERAL INFORMATION MACHINE IDENTIFICATION VEHICLE IDENTIFICATION NUMBER The vehicle identification number CD is stamped into the left side of the frame. NOTE: ____________ _ The vehicle identification number is used to identify your machine and may be used to register you r mach ine with the licensing autho- rity in your state. Starting Serial Number: JV42HROO * HC000101 ENGINE SERIAL NUMBER The engine serial number CD is stamped into the right side of the engine. NOTE: __________________________ _ The first three digits of these numbers are for model identifications; the remaining digits are the unit production number. Starting Serial Number: 2HR-000101 " NOTE: ________________________ __ Designs and specifications are subject to change without notice.

IMPORTANT INFORMATION 1~1J=~lcfeal IMPORTANT INFORMATION 300-000 300-002 300-003 ALL REPLACEMENT PARTS 1. We recommended to use Yamaha genuine parts for all replacements. Use oil and/or grease recommended by Yamaha for assembly and adjustment. Other brands may be similar in function and appearance, but inferior in quality. \ GASKETS, Oil SEALS, AND O·RINGS 1. All gaskets, seals, and O-rings should be replaced when an engine is overhauled. All gasket surfaces, oil seal lips, and a-rings must be cleaned. 2. Properly oil all mating parts and bearings during reassembly. Apply grease to the oil seal lips. LOCK WASHERS/PLATES AND COTTER PINS 1. All lock washers/plates CD and cotter pins must be replaced when they are removed. Lock tab(s) should be bent along the bolt or nut flat(s) after the bolt or nut has been properly tightened. BEARINGS AND OIL SEALS 1. Install the bearing(s) CD and oil seal(s) @ with their manufacturer's marks or numbers facing outward. (In other words, the stamped letters must be on the side exposed to view.) When installing oil seal(s), apply a light coating of light-weight lithium base grease to the seal lip(s). Oil the bearings libe- rally when installing. Do not use compressed air to spin the bearings dry. This causes damage to the bearing surfaces. '-2

I~~I"'I SPECIAL TOOLS 300·001 '·3 CIRCLIPS 1. All circlips should be inspected carefully before reassembly. Always replace piston pin clips after one use. Replace distorted circlips. When installing a circlip CD , make sure that the sharp edged corner ® is positioned opposite to the thrust @ it receives. See the sectional view. @Shaft SPECIAL TOOLS The proper special tools are necessary for com- plete and accurate tune-up and assembly. Using the correct special tool will help prevent damage caused by the use of improper tools or impro- vised techniques. FOR TUNE UP 1. I nductive Tachometer PIN YU-08036 This tool is needed for detecting engine rpm. 2. Inductive Timing Light PIN YM-33277 This tool is necessary for checking ignition timing. 3. Compression Gauge PIN YU-33223 This gauge is used to measure the engine compression.

SPECIAL TOOLS 4. Fuel Level Gauge PIN YM·01312·A This gauge is used to measure the fuel level in the float chamber. 5. Valve Adjusting Tool PIN YM-08035 This tool is necessary for adjusting the valve clearance. FOR ENGINE SERVICE 1. Valve Spring Co")pressor PIN YM·04019 This tool is needed to remove and install the valve assembl ies. 2. Slide Hammer Set PIN YU-Ol083 These tools are used when removing the rocker arm shaft. 3. Flywheel Puller PIN YM-01404 This tool is used to remove the CDI rotor. 1-4

1987-1997 Yamaha Big Bear 350 ATV Service & Repair Manual

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