Yamaha YFM225 ATV 1986–1988 Service & Factory Manual (P/N LIT-11616-04–83)

• Documented coverage: Yamaha YFM225S, model code 59V, beginning with VIN JY459V*GC000101 and engine number 59V-000101. This is a 253-page PDF, Yamaha P/N LIT-11616-04-83, 1st Edition, February 1985.
• Handles the periodic maintenance/lubrication schedule and factory procedures for engine removal, full internal teardown and rebuild, clutch and transmission repair, engine reassembly, and remounting.
• Breaks out the middle gear and shaft-drive final gear as full service areas, including universal-joint work, drive-axle positioning, bearing-housing service, gear-lash checks, shim selection, and ring-gear thrust-clearance inspection.
• Walks through Mikuni VM24SH carburetor removal, disassembly, inspection, assembly, installation, fuel-level checking, and final adjustment.
• Details chassis removal, inspection, installation, and adjustment for the front and rear wheels, rear axle, front drum and rear disc brakes, steering and tie-rod ends, lower arms and front shocks, rear shock, and swingarm.
• Supplies circuit diagrams and fault-finding for electric starting, charging, CDI ignition, lighting, neutral/reverse indicators, and the auxiliary D.C. terminal, with tests for the starter motor, starter relay, starting circuit cut-off relay, coils, switches, fuse, and circuit breaker.
• Includes assembly-level exploded views, component-specific torque tables, lubrication and cable-routing drawings, Yamaha special-tool numbers, and the full YFM225S wiring diagram.

Coverage and Machine Configuration

Model matching is important here. No separate YFM225T or YFM225U supplement is included, so the YFM225S designation, 59V model code, and listed starting numbers should be checked before purchase.

The specifications describe an air-cooled SOHC single-cylinder engine with wet-sump lubrication, electric starting, and Mikuni VM24SH carburetion. Power passes through a wet centrifugal automatic clutch, a constant-mesh dual-range five-speed transmission with reverse, and a shaft-drive final gear. Chassis information corresponds to front drum brakes, a rear single-disc brake, front swing-axle suspension, and a rear swingarm.

Factory Repair Procedures

The routine service section covers valve-clearance inspection, the automatic cam-chain tensioner, idle and throttle adjustment, fuel-system and air-filter service, compression testing, and engine/final-gear lubrication. It then moves through clutch and brake adjustment, steering and suspension checks, wheel bearings, tires, battery service, ignition timing, lights, the fuse, and the circuit breaker.

Engine removal is documented as a machine-level repair. The sequence addresses the related bodywork, rear brake, exhaust, rear wheel drive and swingarm, carburetor, starter motor, wiring, and pipe connections. The overhaul section covers cylinder-head and valve work, camshaft and timing components, piston and cylinder inspection, crankshaft and balancer service, and oil-pump repair. Separate procedures continue through starter gearing, primary and secondary clutches, transmission and sub-transmission, middle gear, and crankcase assembly. Reassembly, adjustment, and remounting are included rather than stopping at disassembly.

The chassis chapter provides repair procedures for wheels, hubs, the rear axle, brakes, steering shaft, knuckles, tie-rod ends, lower arms, shocks, and swingarm bearings. Shaft-drive coverage includes troubleshooting charts, final-drive disassembly, ring-gear and pinion inspection, shim selection, gear-lash adjustment, thrust-clearance checks, and drive-shaft inspection.

Diagrams, Tools, and Reference Data

Yamaha places exploded assembly views ahead of the major disassembly sections. Particularly useful graphics include the carburetor sectional view, middle-gear drive-axle positioning diagram, final-drive and ring-gear positioning views, starting-system circuit diagram, ignition-system troubleshooting charts, and the full YFM225S wiring diagram. The appendices add lubrication diagrams and detailed cable-routing views for the control cables, breather hoses, wire harness, switches, relays, and rear brake cables.

The special-tool section gives factory tool numbers and intended uses. Examples include the YU-01135 crankcase separating tool, YM-04062 universal-joint holder with YM-04096 attachment, YM-33214 final-drive shaft bearing-retainer wrench, YM-01230 gear-lash measurement tool, and YU-33263 or YU-03112 pocket tester. Specification sections provide component-specific tightening torques, fluid and lubricant data, inspection limits, clearances, gear-lash and shim information, and electrical voltage and resistance test values.

Two cautions show why the factory procedures matter. The crankcase-separation section warns against forcing the case halves or striking the gasket surfaces; those mistakes can damage the cases and sealing faces. In the middle-gear procedure, over-tightening the bearing-housing bolts can reduce gear lash enough to damage the gears.

Support the ATV securely before engine, wheel, axle, or swingarm work. Follow Yamaha's handling warnings for the battery and the nitrogen-charged rear shock before beginning those repairs.