YAMAHA BRUIN 250 4x2 ATV 2005-2006 Service Repair Manual YFM250BT (Highly Detailed FSM, Preview)

EB001000 NOTICE This manual was produced by the Yamaha Motor Company primarily for use by Yamaha dealers and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one manual, so it is assumed that anyone who uses this book to perform maintenance and repairs on Yamaha machine has a basic understanding of the mechanical ideas and the procedures of machine repair. Repairs attempted by anyone without this knowledge are likely to render the machine unsafe and unfit for use. Yamaha Motor Company, Ltd. is continually striving to improve all its models. Modifications and significant changes in specifications or procedures will be forwarded to all authorized Yamaha dealers and will appear in future editions of this manual where applicable. NOTE: Designs and specifications are subject to change without notice. IMPORTANT INFORMATION Particularly important information is distinguished in this manual by the following notations. 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 machine operator, a bystander or a person inspecting or repairing the machine. A CAUTION indicates special precautions that must be taken to avoid damage to the machine. A NOTE provides key information to make procedures easier or clearer. WARNING CAUTION: NOTE:

EB002000 HOW TO USE THIS MANUAL MANUAL ORGANIZATION This manual is intended as a handy, easy-to-read reference book for the mechanic. It is divided into chapters, sections and sub-sections. Comprehensive explanations of all installation, removal, disassembly, assembly, repair and inspection procedures are laid out with the individual steps in sequential order. PAGE FEATURES The circled numbers below refer to the features indicated in the sample page. 1 : An abbreviation and symbol in the upper right corner of each page indicates the current chapter. 2 : The current section title is shown at the top of each page.† 3 : Sub-section titles appear in smaller print than the section title.† 4 : Lines of asterisks (*) mark the beginning and end of a particularly important procedure. The steps of such procedures are marked with bullets (•). 5 : Important information such as fluids, special tools and torques are framed and marked with a corresponding symbol. 6 : A circled number refers to an illustrated part. 7 : A circled lower case letter refers to an illustrated dimension or alignment mark. 8 : An upper case letter in a box refers to other illustrated details. 9 : An arrow mark after a given defect suggests the recommended course of action. † : In Chapter 3, “Periodic Inspection and Adjustment”, it is usually the current sub-section title that appears at the top of each page, instead of the current section title. EXPLODED DIAGRAMS To help identify parts and clarify procedure steps, there are exploded diagrams at the start of each disassembly section.

EB003000 ILLUSTRATED SYMBOLS Illustrated symbols 1 to 9 are printed on the top right of each page and indicate the subject of each chapter. 1 General information 2 Specifications 3 Periodic inspections and adjustments 4 Engine 5 Carburetion 6 Drive train 7 Chassis 8 Electrical 9 Troubleshooting Illustrated symbols 0 to F are used to identify the specifications appearing in the text. 0 Filling fluid A Lubricant B Special tool C Torque D Wear limit, clearance E Engine speed F Ω, V, A Illustrated symbols G to L in the exploded diagrams indicate the types of lubricants and lubrication points. G Apply engine oil H Apply gear oil I Apply molybdenum disulfide oil J Apply wheel bearing grease K Apply lightweight lithium-soap base grease L Apply molybdenum disulfide grease Illustrated symbols M to N in the exploded diagrams indicate where to apply a locking agent M and when to install a new part N. M Apply the locking agent (LOCTITE  ) N Replace 1 2 3 4 5 6 7 8 9 0 A B C D E F G H I J K L M N GEN INFO SPEC INSP ADJ ENG CARB DRIV CHAS – + ELEC TRBL SHTG T R . . G M E B LS M LT New

CHAPTER TITLES GENERAL INFORMATION 1 SPECIFICATIONS SPEC 2 PERIODIC INSPECTION AND ADJUSTMENT 3 ENGINE OVERHAUL ENG 4 CARBURETION CARB 5 DRIVE TRAIN DRIVE 6 CHASSIS CHAS 7 ELECTRICAL ELEC 8 TROUBLESHOOTING 9 GEN INFO INSP ADJ – + TRBL SHTG

CONTENTS CHAPTER 1. GENERAL INFORMATION MACHINE IDENTIFICATION ........................................................................ 1-1 VEHICLE IDENTIFICATION NUMBER .................................................. 1-1 MODEL LABEL ...................................................................................... 1-1 IMPORTANT INFORMATION ...................................................................... 1-2 PREPARATION FOR REMOVAL PROCEDURES ................................. 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 OF CONNECTIONS ................................................................... 1-4 SPECIAL TOOLS ........................................................................................... 1-5 CHAPTER 2. SPECIFICATIONS GENERAL SPECIFICATIONS ....................................................................... 2-1 MAINTENANCE SPECIFICATIONS ............................................................. 2-4 ENGINE ................................................................................................. 2-4 CHASSIS ............................................................................................. 2-14 ELECTRICAL ........................................................................................ 2-18 HOW TO USE THE CONVERSION TABLE ................................................ 2-20 GENERAL TORQUE SPECIFICATIONS ..................................................... 2-20 LUBRICATION POINTS AND LUBRICANT TYPES ................................... 2-21 ENGINE ............................................................................................... 2-21 CHASSIS ............................................................................................. 2-22 LUBRICATION DIAGRAMS ........................................................................ 2-23 CABLE ROUTING ....................................................................................... 2-25

CHAPTER 3. PERIODIC INSPECTIONS AND ADJUSTMENTS INTRODUCTION ........................................................................................... 3-1 PERIODIC MAINTENANCE/LUBRICATION ................................................ 3-1 FENDER AND FUEL TANK ........................................................................... 3-3 FRONT FENDER .................................................................................... 3-3 REAR FENDER ...................................................................................... 3-5 FUEL TANK ........................................................................................... 3-7 ENGINE ....................................................................................................... 3-10 VALVE CLEARANCE ADJUSTMENT ................................................. 3-10 TIMING CHAIN TENSIONER ADJUSTMENT ................................... 3-12 IDLE SPEED ADJUSTMENT .............................................................. 3-13 THROTTLE CABLE FREE PLAY ADJUSTMENT ................................ 3-14 SPEED LIMITER ADJUSTMENT ........................................................ 3-15 SPARK PLUG INSPECTION ............................................................... 3-15 IGNITION TIMING CHECK ................................................................. 3-17 COMPRESSION PRESSURE MEASUREMENT ................................. 3-18 ENGINE OIL LEVEL INSPECTION ...................................................... 3-19 ENGINE OIL REPLACEMENT ............................................................. 3-20 CLUTCH ADJUSTMENT .................................................................... 3-23 AIR FILTER CLEANING ....................................................................... 3-23 CHASSIS ..................................................................................................... 3-26 FRONT AND REAR BRAKE LINING INSPECTION ............................ 3-26 FRONT BRAKE ADJUSTMENT .......................................................... 3-26 REAR BRAKE LEVER AND PEDAL ADJUSTMENT .......................... 3-27 DRIVE SELECT LEVER POSITION ADJUSTMENT ........................... 3-29 FINAL DRIVE GEAR OIL LEVEL INSPECTION ................................... 3-29 FINAL DRIVE GEAR OIL REPLACEMENT .......................................... 3-30 DRIVE SHAFT DUST BOOT INSPECTION ......................................... 3-31 STEERING SYSTEM INSPECTION .................................................... 3-31 TOE-IN ADJUSTMENT ....................................................................... 3-32 FRONT AND REAR SHOCK ABSORBERS INSPECTION .................. 3-34 REAR SHOCK ABSORBER ADJUSTMENT ....................................... 3-34 TIRE INSPECTION .............................................................................. 3-35 WHEEL INSPECTION .......................................................................... 3-37 1 SPEC 2 3 ENG 4 CARB 5 DRIVE 6 CHAS 7 ELEC 8 9 GEN INFO INSP ADJ – + TRBL SHTG

ELECTRICAL ............................................................................................... 3-38 BATTERY INSPECTION ...................................................................... 3-38 FUSE INSPECTION ............................................................................. 3-41 HEADLIGHT BEAM ADJUSTMENT ................................................... 3-42 HEADLIGHT BULB REPLACEMENT .................................................. 3-42 CHAPTER 4. ENGINE OVERHAUL ENGINE REMOVAL ...................................................................................... 4-1 PREPARATION FOR REMOVAL ........................................................... 4-1 FRONT FENDER AND REAR FENDER ................................................. 4-1 ENGINE OIL .......................................................................................... 4-2 EXHAUST PIPE AND MUFFLER .......................................................... 4-2 CARBURETOR ...................................................................................... 4-2 STARTER MOTOR ................................................................................ 4-3 REAR BRAKE CABLES AND FOOTREST ............................................ 4-3 WIRINGS AND HOSES ......................................................................... 4-3 REAR WHEEL DRIVE ASSEMBLY AND SWINGARM ........................ 4-4 ENGINE REMOVAL .............................................................................. 4-4 ENGINE DISASSEMBLY .............................................................................. 4-5 CYLINDER HEAD ASSEMBLY, CYLINDER AND PISTON .................. 4-5 STARTER PULLEY CDI MAGNETO ..................................................... 4-8 MIDDLE DRIVEN PINION GEAR ........................................................ 4-10 PRIMARY AND SECONDARY CLUTCHES ........................................ 4-11 OIL PUMP AND SHIFTER ................................................................... 4-13 BALANCER DRIVEN GEAR ................................................................ 4-14 CRANKCASE (LEFT) ........................................................................... 4-15 BALANCER SHAFT, TRANSMISSION AND CRANKSHAFT ............ 4-16 CYLINDER HEAD ................................................................................ 4-17 VALVE ................................................................................................. 4-18 RECOIL STARTER ............................................................................... 4-19 INSPECTION AND REPAIR ........................................................................ 4-20 CYLINDER HEAD ................................................................................ 4-20 INTAKE AND EXHAUST VALVE ........................................................ 4-20 VALVE GUIDE ..................................................................................... 4-21 VALVE SEAT ....................................................................................... 4-22 VALVE SPRING ................................................................................... 4-25 VALVE INSTALLATION ...................................................................... 4-26 CAM SHAFT ........................................................................................ 4-27 ROCKER ARM AND ROCKER ARM SHAFT ...................................... 4-28

TIMING CHAIN ................................................................................... 4-30 CAM SPROCKET AND CAM DRIVE SPROCKET ............................... 4-31 TIMING CHAIN GUIDE ....................................................................... 4-31 TIMING CHAIN TENSIONER .............................................................. 4-31 TAPPET COVER AND CAM SPROCKET COVER ............................... 4-32 CYLINDER AND PISTON .................................................................... 4-32 PISTON RING AND PISTON PIN ....................................................... 4-33 CRANKSHAFT ..................................................................................... 4-36 BALANCER DRIVE GEAR AND DRIVEN GEARS .............................. 4-37 PRIMARY GEARS AND STARTER ..................................................... 4-37 PRIMARY CLUTCH ............................................................................. 4-38 SECONDARY CLUTCH ....................................................................... 4-38 OIL PUMP ............................................................................................ 4-40 TRANSMISSION AND SHIFTER ........................................................ 4-41 MIDDLE GEAR .................................................................................... 4-43 BEARINGS AND OIL SEALS .............................................................. 4-43 CIRCLIPS AND WASHERS ................................................................. 4-43 CRANKCASE ....................................................................................... 4-43 RECOIL STARTER ............................................................................... 4-44 ENGINE ASSEMBLY AND ADJUSTMENT ............................................... 4-45 RECOIL STARTER ............................................................................... 4-45 CRANKSHAFT/BALANCER ................................................................ 4-47 TRANSMISSION ................................................................................. 4-48 SHIFTER .............................................................................................. 4-49 CRANKSHAFT, TRANSMISSION AND BALANCER SHAFT ............ 4-50 CRANKCASE (LEFT) ........................................................................... 4-51 BALANCER DRIVEN AND DRIVE GEARS ......................................... 4-51 SHIFT SHAFT/OIL PUMP .................................................................... 4-53 SHIFTER AND OIL PUMP ................................................................... 4-54 CLUTCH ............................................................................................... 4-56 PRIMARY AND SECONDARY CLUTCHES ........................................ 4-57 MIDDLE DRIVEN PINION GEAR ........................................................ 4-61 STARTER PULLEY (EXCEPT FOR USA)/CDI MAGNETO ................. 4-62 STARTER PULLEY (EXCEPT FOR USA) AND CDI MAGNETO ........ 4-63 CYLINDER AND CYLINDER HEAD ASSEMBLY ................................ 4-65 PISTON, CAMSHAFT AND TIMING CHAIN ...................................... 4-66 CYLINDER HEAD ASSEMBLY, CYLINDER AND PISTON ................ 4-67 REMOUNTING ENGINE ..................................................................... 4-72 1 SPEC 2 3 ENG 4 CARB 5 DRIVE 6 CHAS 7 ELEC 8 9 GEN INFO INSP ADJ – + TRBL SHTG

CHAPTER 5. CARBURETION CARBURETOR .............................................................................................. 5-1 REMOVAL ............................................................................................. 5-2 DISASSEMBLY ..................................................................................... 5-2 INSPECTION ......................................................................................... 5-4 ASSEMBLY ........................................................................................... 5-6 INSTALLATION ..................................................................................... 5-8 FUEL LEVEL ADJUSTMENT ................................................................ 5-9 CHAPTER 6. DRIVE TRAIN MIDDLE GEAR SERVICE .............................................................................. 6-1 MIDDLE GEAR ...................................................................................... 6-1 MIDDLE GEAR SHIMS ......................................................................... 6-2 REMOVAL ............................................................................................. 6-3 DISASSEMBLY ..................................................................................... 6-5 INSPECTION ......................................................................................... 6-7 MIDDLE GEAR SHIM SELECTION ....................................................... 6-9 ASSEMBLY ......................................................................................... 6-16 MIDDLE GEAR LASH ADJUSTMENT ............................................... 6-21 INSTALLATION ................................................................................... 6-22 FINAL DRIVE GEAR AND DRIVE SHAFT .................................................. 6-24 TROUBLESHOOTING ......................................................................... 6-25 REMOVAL ........................................................................................... 6-28 DISASSEMBLY ................................................................................... 6-29 INSPECTION ....................................................................................... 6-31 FINAL DRIVE PINION GEAR AND RING GEAR SHIM SELECTION ............................................. 6-32 ASSEMBLY ......................................................................................... 6-35 FINAL GEAR GEAR LASH MEASUREMENT AND ADJUSTMENT ....................................................................... 6-37 INSTALLATION ................................................................................... 6-40

YAMAHA BRUIN 250 4x2 ATV 2005-2006 Service Repair Manual YFM250BT (Highly Detailed FSM, Preview)

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