Yamaha Grizzly 660 660FP ATV 2002–2006 Service Manual (P/N LIT-11616-15-01)

• Exact document scope: A 408-page PDF for the Yamaha YFM660FP identified in the manual by model codes 5KM1 and 5KM5. This is Yamaha publication LIT-11616-15-01, first edition, May 2001; the cover also carries code 5KM-28197-E0.
• Engine and internal transmission repair: Covers engine removal and installation, cylinder head and valve-train work, piston and cylinder inspection, recoil starter and AC magneto service, crankcase separation, crankshaft and oil-pump repair, and transmission disassembly and reassembly.
• CVT and driveline procedures: Details the primary and secondary sheaves, centrifugal clutch and V-belt, middle drive and driven shafts, shim selection and gear-lash adjustment, front and rear CV joints, differential, final drive, and 2WD/4WD/differential-lock gear-motor checks.
• Fuel, cooling, and scheduled service: Includes BSR42 carburetor disassembly, inspection, assembly, and fuel-level adjustment; radiator, cap, thermostat, and water-pump testing; plus valve-clearance, ignition-timing, compression, coolant, lubrication, and control-cable procedures.
• Chassis and hydraulic brake work: Provides wheel-hub and brake-disc inspection, pad replacement, master-cylinder and caliper service, brake bleeding, steering-stem repair, tie-rod and ball-joint checks, front and rear arm service, knuckle and stabilizer inspection, shock-absorber checks, and toe-in adjustment.
• Electrical diagnosis and shop data: Supplies circuit-based troubleshooting for ignition, starting, charging, lighting, signal, cooling-fan, and 2WD/4WD selecting systems, together with switch and connector checks, wiring and hose routing, special-tool part numbers, torque tables, fluid data, wear limits, clearances, and electrical test specifications.

Yamaha states that this manual was produced primarily for its dealers and qualified mechanics, and it assumes the user already understands basic mechanical principles and repair procedures. It is therefore best suited to trained technicians or experienced mechanics with the measuring tools, pullers, holders, and other shop equipment required for the work. This is factory service documentation rather than an owner's maintenance guide.

Repair Depth and System Coverage

The engine chapters go well beyond routine tune-up information. They address the decompression mechanism, timing chain and tensioner, camshaft, rocker arms, valves and guides, piston rings, starter clutch, balancer drive, oil-pressure components, shift forks, shift cam, and the reverse-drive chain. Exploded assembly views and job charts establish removal or disassembly order, while the accompanying text adds inspection criteria, assembly notes, adjustments, and operational checks.

The driveline material explains Yamaha's On-Command front differential in 2WD, 4WD, and differential-lock modes, including gear-motor action, standby behavior, and indicator-light logic. Separate repair sections cover middle-gear shim calculation and backlash measurement, differential lash adjustment, final-drive pinion and ring-gear positioning, universal-joint work, and drive-train noise and leak diagnosis.

Diagrams, Tools, and Specifications

Representative visual references include coolant-flow and oil-flow diagrams, cable-and-hose routing views, ignition and electric-starting circuit diagrams, the 2WD/4WD selecting-system circuit, and the full YFM660FP wiring diagram. The electrical chapters pair those schematics with continuity, resistance, and voltage checks rather than relying only on symptom lists.

The special-tool section gives both U.S./Canadian and 90890-series numbers. Examples include the crankcase separating tool YU-01135-A / 90890-01135, gear-lash measurement tool YM-01467 / 90890-01467, sheave spring compressor YM-04134 / 90890-04134, pocket tester YU-03112 / 90890-03112, and radiator-cap tester YU-24460-01 / 90890-01325. Specification tables cover component-specific torques, lubrication points, fluid capacities and approved fluids, service limits, clearances, pressure tests, and electrical values.

Manual-Specific Service Cautions

The drive-train chapter warns that insufficient gear lash is destructive to the gear teeth. It also identifies the front differential's internal gear unit as a factory-assembled component that will malfunction if disassembled. In the brake section, Yamaha cautions that ordinary solvents can swell and distort internal caliper and master-cylinder seals.

Because this repair manual covers a pressurized cooling system, hydraulic brakes, rotating engine and driveline components, and vehicle support for wheel or suspension work, proper shop safety and the manual's model-specific specifications should be followed throughout.