Yamaha Grizzly 660 Service Manual

The Yamaha Grizzly 660 is a high-performance all-terrain vehicle (ATV) featuring a 660cc liquid-cooled, SOHC, 4-stroke engine, Ultramatic automatic transmission with On-Command 2WD/4WD, independent front and rear suspension, hydraulic disc brakes, and electric start. This service manual provides comprehensive information for maintenance, troubleshooting, and repair procedures to ensure optimal performance and longevity of your ATV. Below are key sections covering specifications, maintenance, engine service, transmission, electrical system, chassis, and troubleshooting.

General Information & Specifications

Key identification: Model code, VIN location, general dimensions and capacities.

Periodic Maintenance

Follow the maintenance schedule to ensure reliability and safety.

1. Pre-ride Inspection: Check tires, brakes, lights, controls, and fluid levels.
2. Engine Oil: Change oil and filter every 100 hours or 6 months. Use recommended 10W-30 or 10W-40.
3. Air Filter: Clean foam element every 20-50 hours; replace if damaged.
4. Spark Plug: Inspect and clean every 100 hours; gap: 0.028-0.031 in (0.7-0.8 mm).
5. Drive Belt: Inspect for wear/cracks every 200 hours.
6. Brake Fluid: Check level and condition; replace every 2 years.
7. Differential Oil: Front and rear differential oil change every 200 hours.

WARNING! Always perform maintenance in a well-ventilated area with the engine off and cool. Use proper tools and safety equipment.

Engine Service

Procedures for top-end and bottom-end engine service.

1. Cylinder Head Removal: Drain coolant, remove valve cover, cam chain tensioner, and cylinder head bolts in sequence.
2. Valve Adjustment: Set piston at TDC compression; adjust intake: 0.004-0.006 in (0.10-0.15 mm), exhaust: 0.007-0.009 in (0.18-0.23 mm).
3. Piston & Cylinder: Measure cylinder bore and piston clearance; service limit: 0.0039 in (0.10 mm).
4. Crankshaft & Bearings: Check runout and bearing clearance; replace if out of specification.
5. Camshaft & Timing Chain: Inspect cam lobes and chain tensioner; replace if worn.

CAUTION! Label all parts and fasteners during disassembly. Use a torque wrench for reassembly.

Fuel System & Carburetor

Maintenance and adjustment of the Mikuni BSR36 carburetor.

• Carburetor Removal: Disconnect fuel line, throttle cables, and vent hoses.
• Cleaning: Disassemble jets and passages; clean with carburetor cleaner.
• Float Level: Adjust to 0.59-0.67 in (15-17 mm).
• Pilot Screw: Initial setting: 2 turns out from lightly seated.
• Throttle Sync: Synchronize carburetor with throttle position sensor if equipped.
• Fuel Pump: Test pressure (2.1-2.4 psi) and flow.

Electrical System

Testing and service of battery, charging system, ignition, and lighting.

Battery: 12V, 12Ah. Maintain specific gravity at 1.260-1.280. Keep terminals clean and tight.

Charging System: Stator coil resistance: 0.36-0.48 Ω at 68°F (20°C). Regulator/Rectifier output: 13.5-15.5 V at 5000 RPM.

Ignition System: Primary coil resistance: 0.56-0.84 Ω. Secondary coil resistance: 8.0-12.0 kΩ. Spark plug cap: 5 kΩ.

Starter Motor: Brush length service limit: 0.24 in (6.0 mm). Commutator diameter limit: 1.18 in (30.0 mm).

Chassis & Suspension

Inspection and service of frame, suspension components, and steering.

1. Wheel Alignment (Toe-in): Adjust tie rods to achieve 0-10 mm toe-in.
2. Swingarm Pivot Bearings: Lubricate every 200 hours; check for play.
3. Front A-Arms & Bushings: Inspect for damage and wear; replace if necessary.
4. Shock Absorbers: Check for leaks and damping performance; adjust preload as needed.
5. Steering Stem Bearings: Adjust nut to eliminate free play; lubricate periodically.

Tip: Use a hoist or jack stands to safely lift the ATV for chassis work.

Transmission & Drive System

Service for Ultramatic transmission, drive belt, and On-Command system.

1. Drive Belt Inspection: Remove cover; check for cracks, fraying, and width (service limit: 1.18 in / 30 mm).
2. Sheave Service: Clean movable and fixed sheaves; inspect rollers and sliding surfaces.
3. On-Command System: Check vacuum lines and actuator for proper 2WD/4WD engagement.
4. Front Differential: Drain and refill with 80W-90 gear oil (0.42 qt / 0.4 L).
5. Rear Gearcase: Drain and refill with 80W-90 gear oil (0.53 qt / 0.5 L).

WARNING! The drive belt is under tension; keep hands clear when the engine is running.

Brake System

Service procedures for hydraulic disc brakes.

Brake Pad Inspection: Replace pads if thickness is less than 0.12 in (3.0 mm).

Brake Disc: Check for runout (limit: 0.012 in / 0.3 mm) and thickness (limit: 0.20 in / 5.0 mm).

Bleeding Brakes: Use DOT 4 brake fluid. Fill reservoir, attach tube to bleeder valve, pump lever/pedal, and tighten valve.

Parking Brake Adjustment: Adjust cable at lever until rear wheels lock with 3-5 clicks.

Troubleshooting

Wiring Diagrams

Complete wiring schematics for the Grizzly 660 are provided in the full manual. Key systems include:

• Starting & Charging Circuit
• Ignition & CDI System
• Lighting & Indicator Circuits
• On-Command 4WD Control
• Fuel Gauge & Speedometer

Note: Refer to the color-coded diagrams for wire colors and connector locations.

Torque Specifications

Critical fastener torque values (ft-lb / N·m).

CAUTION! Always use a calibrated torque wrench. Do not overtighten.