Yamaha YZ125 & YZ250 (1985-1987) &YZ490 (1985-1990) Motorcycle Service Repair Manual Description Clymer motorcycle repair manuals are written specifically for the do-it-yourself enthusiast. From basic maintenance to troubleshooting to complete overhaul Clymer manuals provide the information you need. The most important tool in your tool box may be your Clymer manual get one today. Every Clymer manual contains hundreds of original photographs and illustrations developed from a complete disassembly and assembly of a motorcycle. This in addition to extensive research allows Clymer to achieve an unmatched level of detail accuracy and clarity. The step-by-step instructions and two-column text with large print are user-friendly. Bold figure numbers make it easy to quickly match instructions with illustrations and photos. Thumb-tabbed chapters numbered table of contents and an extensive index make it possible to locate the desired section quickly. Contents This Yamaha motorcycle manual is 272 pages. QUICK REFERENCE DATA CHAPTER ONE / GENERAL INFORMATION Manual organization / Service hints / Torque specifications / Safety first / Special tips / Mechanic s tips / Parts replacement / Expendable supplies / Tools / What year is it? / Serial numbers / Specifications CHAPTER TWO / TROUBLESHOOTING Operating requirements / Troubleshooting instruments / Emergency troubleshooting / Engine starting / Engine performance / Engine noises / Excessive vibration / Two-stroke pressure test / Clutch / Transmission / Brakes / Water-cooling system (YZ125 and YZ250) / Front suspension and steering / Ignition system / Specifications CHAPTER THREE / LUBRICATION MAINTENANCE AND TUNE-UP Pre-checks / Tires and wheels / Lubricants / Cleaning solvent / Periodic lubrication / Engine lubrication / Clutch/Transmission oil checking and changing / Front fork oil change / Front fork air pressure / Periodic maintenance / Drive chain adjustment / Clutch adjustment / Fuel filter and shutoff valve / Coolant change / Air cleaner service / Engine tune-up / Cylinder head nuts torque / Spark plug / Ignition timing / Carburetor pilot screw and idle speed adjustment / Decarbonizing engine and exhaust system / Storage / Specifications CHAPTER FOUR / ENGINE Engine principles / Servicing engine in frame / Engine removal installation / Cylinder head / Cylinder / Piston wrist pin and piston rings / Break-in procedure / Magneto / Reed valve assembly / Crankcase and crankshaft / Kickstarter / Service and adjustment / Specifications CHAPTER FIVE / CLUTCH AND TRANSMISSION Clutch / Clutch cable / External shift mechanism / Primary drive gear / Drive sprocket / Transmission / Specifications CHAPTER SIX / FUEL POWER VALVE AND EXHAUST SYSTEMS Air cleaner / Carburetor operation / Carburetor service / Carburetor adjustments / Fuel shutoff valve / Fuel tank / Energy induction system (YZ490) / Power valve induction system / Exhaust system / Exhaust system decarbonizing / Exhaust system repair / Specifications CHAPTER SEVEN / IGNITION SYSTEM Capacitor discharge ignition / Magneto (outer rotor) / Magneto (inner rotor) / Magneto coil testing (all models) / Capacitor discharge ignition unit / Ignition coil / Spark plug / Engine kill switch / Wiring diagrams / Specifications CHAPTER EIGHT / COOLING SYTEM Cooling system inspection / Radiator / Water pump / Specifications CHAPTER NINE / FRONT SUSPENSION AND STEERING Front wheel / Front hub / Wheels / Tire changing / Tire repairs / Handlebar / Steering head / Front fork / Specification...