2002 Yamaha Grizzly 660 Service Manual

The 2002 Yamaha Grizzly 660 is a four-wheel drive all-terrain vehicle (ATV) powered by a 660cc liquid-cooled, 4-stroke, SOHC engine. This service manual provides comprehensive information for maintenance, troubleshooting, and repair. It covers the engine, transmission, chassis, electrical system, and periodic maintenance procedures. Below are key sections for safety, specifications, maintenance, troubleshooting, and repair procedures.

1. General Information 2. Specifications 3. Periodic Maintenance 4. Engine 5. Transmission & Drive System 6. Chassis 7. Electrical System 8. Troubleshooting 9. Wiring Diagrams 10. Lubrication Points 11. Torque Specifications

General Information

This manual is intended for qualified service technicians. It provides detailed procedures for inspection, adjustment, and repair of the 2002 Yamaha Grizzly 660 ATV. Always follow safety precautions and use proper tools.

Item	Description
Model	Yamaha Grizzly 660 (YFM660FW)
Type	4WD All-Terrain Vehicle
Engine Type	Liquid-cooled, 4-stroke, SOHC
Displacement	660 cm³
Starting System	Electric start with auxiliary recoil
Drive System	2WD/4WD with differential lock
Fuel System	Mikuni BSR42 carburetor
Transmission	Automatic Ultramatic V-belt with high/low range
Front Suspension	Independent double wishbone
Rear Suspension	Swingarm with adjustable shock

Specifications

Detailed technical specifications for the 2002 Yamaha Grizzly 660.

Overall Length: 2,165 mm (85.2 in).
Overall Width: 1,165 mm (45.9 in).
Overall Height: 1,225 mm (48.2 in).
Wheelbase: 1,270 mm (50.0 in).
Ground Clearance: 260 mm (10.2 in).
Dry Weight: 291 kg (642 lb).
Engine: 660cc, liquid-cooled, 4-stroke, SOHC, 4-valve.
Bore x Stroke: 102.0 x 80.5 mm.
Compression Ratio: 9.5:1.
Fuel Capacity: 18.5 L (4.9 US gal).
Oil Capacity: 3.0 L (3.2 US qt) with filter change.
Transmission: Automatic Ultramatic V-belt, high/low range, reverse.
Front Tires: AT25 x 8-12.
Rear Tires: AT25 x 10-12.

Periodic Maintenance

Follow the maintenance schedule to ensure optimal performance and longevity.

Pre-ride Inspection: Check tires, brakes, lights, controls, and fluid levels.
Engine Oil: Change every 100 hours or 6 months; use Yamalube 4 (10W-30) or equivalent.
Oil Filter: Replace with every oil change.
Air Filter: Clean every 20 hours; replace if damaged.
Spark Plug: Check gap every 100 hours; replace every 200 hours (NGK CR7E).
Drive Belt: Inspect every 100 hours for wear/cracks.
Front & Rear Differential Oil: Change every 200 hours (SAE 80W-90 GL-5).
Brake Fluid: Check level; replace every 2 years (DOT 4).
Wheel Bearings: Lubricate every 200 hours.
Valve Clearance: Inspect every 200 hours (Intake: 0.10–0.15 mm, Exhaust: 0.15–0.20 mm).

WARNING! Always perform maintenance with engine off and cool. Use proper safety equipment.

Engine

Detailed service procedures for the 660cc engine.

Cylinder Head Removal: Drain coolant, remove intake/exhaust, disconnect cables, unbolt head.

Piston & Cylinder: Inspect for wear, scoring; measure cylinder bore (standard: 102.000–102.015 mm).

Crankshaft & Connecting Rod: Check big-end side clearance (0.35–0.65 mm).

Valve System: Adjust clearance with feeler gauge; inspect valves/seats.

Carburetor: Clean jets (main #142.5, pilot #45); adjust float height (16.5 mm).

Cooling System: Flush radiator; check thermostat opening (80–84°C).

Lubrication: Oil pump clearance (0.05–0.13 mm); replace oil strainer.

Transmission & Drive System

Service for Ultramatic transmission and drive components.

Drive Belt Inspection: Remove cover; check for cracks, fraying, wear (width limit: 28.5 mm).
Primary/Secondary Clutch: Clean sheaves; check rollers for flat spots; lubricate movable face.
Gear Reduction Unit: Drain oil; inspect gears/bearings; refill (0.35 L SAE 80W-90).
Front Differential: Remove skid plate; drain oil; check ring/pinion backlash (0.10–0.20 mm).
Rear Differential: Similar procedure; includes differential lock mechanism inspection.
Drive Shafts: Check CV joints for wear; replace boot if torn.
2WD/4WD Selector: Test operation; adjust linkage if necessary.

Tip: Always clean area before disassembly to prevent contamination.

Chassis

Frame, suspension, steering, and brake systems.

Component	Service Procedure
Front Suspension	Inspect A-arms, bushings, ball joints; replace if loose. Shock absorber oil change.
Rear Suspension	Check swingarm pivot bearings; adjust preload on shock.
Steering	Check for play; adjust tie-rod ends; lubricate steering stem bearings.
Front Brakes	Dual hydraulic disc; pad thickness limit: 1.5 mm; bleed system.
Rear Brakes	Hydraulic disc with parking brake; adjust cable tension.
Wheels & Tires	Check for damage; tighten lug nuts to spec (55 N·m).
Frame	Inspect for cracks, especially at stress points.

Electrical System

Battery, charging, ignition, lighting, and starting system.

Battery: Maintain fluid level; specific gravity: 1.280 at 20°C; voltage: 12.8 V fully charged.
Charging System: Test stator resistance (0.21–0.31 Ω at 20°C); regulator/rectifier output: 13.5–15.5 V at 5,000 rpm.
Ignition System: Check coil resistance (primary: 0.56–0.84 Ω, secondary: 8.9–13.4 kΩ).
Starting System: Inspect starter motor brushes (limit: 6.5 mm); solenoid engagement.
Lights & Switches: Test headlight (12V 35/35W), taillight, brake light, indicators.
Wiring Harness: Check for chafing, corrosion; secure connections.

WARNING! Disconnect battery negative terminal before electrical work.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Weak battery, faulty spark, fuel issue	Check battery voltage, spark plug, fuel flow, carburetor.
Poor performance	Clogged air filter, worn drive belt	Clean/replace air filter; inspect drive belt.
Overheating	Low coolant, clogged radiator	Check coolant level; clean radiator fins; test thermostat.
Transmission slipping	Worn drive belt, clutch issue	Inspect belt; service primary/secondary clutch.
4WD not engaging	Faulty actuator, linkage	Test 4WD actuator; check linkage adjustment.
Electrical failure	Blown fuse, bad ground	Check fuses (main 30A, others 10A/15A); clean ground connections.
Brakes dragging	Stuck caliper, contaminated fluid	Clean caliper pistons; flush brake fluid.

Wiring Diagrams

Refer to separate fold-out diagrams included with manual for complete electrical schematics, including color codes and connector locations for the entire ATV system.

Lubrication Points

Critical lubrication points and recommended lubricants.

Steering Stem Bearings: Grease (Yamaha Grease A).
Swingarm Pivot: Grease (Yamaha Grease A).
Brake & Clutch Levers: Light oil.
Throttle Cable: Cable lubricant.
Drive Shaft Splines: Molybdenum disulfide grease.
Wheel Bearings: High-temperature bearing grease.

Torque Specifications

Essential torque values for reassembly (values in N·m).

Fastener	Torque
Cylinder Head Bolts	49 (in sequence)
Spark Plug	13
Oil Drain Plug	43
Wheel Lug Nuts	55
Front Sprocket Nut	105
Swingarm Pivot Bolt	113
Shock Absorber Mounting	40
Steering Stem Nut	75
Brake Caliper Bolts	23
Engine Mount Bolts	40–60

Note: Always use a calibrated torque wrench. Lubricate threads where specified.

Service Support: For genuine parts and technical assistance, contact an authorized Yamaha dealer or visit www.yamaha-motor.com.