2002 Grizzly 660 Service Manual

The 2002 Yamaha Grizzly 660 is a 4x4 all-terrain vehicle (ATV) featuring a 660cc liquid-cooled, SOHC, four-stroke engine with Ultramatic automatic transmission, On-Command 2WD/4WD with differential lock, independent double-wishbone front suspension, and a swingarm rear suspension. This service manual provides comprehensive information for maintenance, troubleshooting, repair, and specifications. Below are key sections covering safety, periodic maintenance, engine service, transmission, chassis, electrical, and troubleshooting.

1. General Information & Safety 2. Periodic Maintenance & Lubrication 3. Engine 4. Cooling System 5. Fuel System 6. Electrical System 7. Ultramatic Transmission 8. Chassis & Final Drive 9. Brakes & Wheels 10. Troubleshooting 11. Specifications

General Information & Safety

This manual is intended for qualified service technicians. Always follow safety precautions to prevent injury or damage.

Topic	Description
Identification	Vehicle Identification Number (VIN) location, model code, color code
General Precautions	Use proper tools; follow torque specifications; disconnect battery before service
Safety Symbols	Warning, Caution, Note symbols explained
Lift Points	Proper lifting procedures for ATV service

WARNING! Always wear safety glasses and protective clothing. Ensure ATV is on a level, stable surface before servicing.

Periodic Maintenance & Lubrication

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 recommended 10W-30 or 10W-40.
Oil filter: Replace with every oil change.
Air filter: Clean every 20 hours; replace if damaged.
Drive chain: Adjust tension and lubricate every 20 hours.
Brake fluid: Inspect level; replace every 2 years.
Coolant: Replace every 2 years with ethylene glycol type.
Grease points: Lubricate suspension, steering, and drive shaft fittings.

CAUTION! Use only Yamaha Genuine Parts and recommended lubricants. Improper maintenance can void warranty.

Engine

The 660cc engine is a single-cylinder, four-stroke with SOHC and five valves.

Compression Ratio: 9.5:1
Bore x Stroke: 102.0 mm x 80.5 mm
Starting System: Electric starter with auxiliary recoil
Lubrication System: Wet sump
Oil Capacity: 3.0 L (3.2 US qt) with filter change

Service procedures: Cylinder head removal, valve adjustment (intake 0.10–0.15 mm, exhaust 0.15–0.20 mm), piston and cylinder service, crankshaft and connecting rod inspection.

Cooling System

Liquid-cooled with radiator, thermostat, and water pump.

Coolant capacity: 1.65 L (1.74 US qt)
Thermostat opens: 80–84°C (176–183°F)
Radiator cap relief pressure: 93–123 kPa (13.5–17.8 psi)

Inspection: Check for leaks, test radiator cap, inspect hoses, flush system every 2 years.

Fuel System

Includes fuel tank, fuel pump, carburetor (Mikuni BSR40), and throttle cable.

Component	Specification
Fuel Type	Unleaded gasoline (87 octane or higher)
Fuel Tank Capacity	18.5 L (4.9 US gal)
Carburetor Idle Speed	1400 ± 100 rpm
Pilot Screw Setting	2-1/4 turns out (initial setting)

Service: Carburetor adjustment, float level check (16.5 mm), fuel filter replacement.

Electrical System

12V DC system with battery, AC magneto, regulator/rectifier, starter motor, and lighting.

Battery: YTZ7S (12V 6Ah)
Charging System: Three-phase AC magneto
Spark Plug: NGK CR7E (gap 0.6–0.7 mm)
Fuses: Main 30A, Headlight 10A, Signal 10A

Troubleshooting: Use multimeter to test voltage, resistance, and continuity. Refer to wiring diagram.

Ultramatic Transmission

Fully automatic V-belt transmission with high/low range, reverse, and engine braking.

Transmission oil: Yamaha Hypoid Gear Oil SAE 80 API GL-4
Oil capacity: 0.95 L (1.0 US qt)
Drive belt width (new): 27.0 mm (service limit 25.5 mm)

Adjustment: Drive belt tension, shift cable adjustment, 2WD/4WD linkage.

Chassis & Final Drive

Double-wishbone front suspension with 165 mm travel; swingarm rear with 190 mm travel.

Front Shock Absorber: Adjustable preload
Rear Shock Absorber: Adjustable preload and rebound damping
Wheelbase: 1225 mm (48.2 in)
Ground Clearance: 265 mm (10.4 in)
Final Drive: Shaft drive with bevel gear
Final Drive Oil: SAE 80 API GL-4, 0.35 L (0.37 US qt)

Brakes & Wheels

Dual hydraulic disc brakes front, single hydraulic disc rear.

Component	Specification
Front Brake Disc Thickness	4.0 mm (service limit 3.5 mm)
Rear Brake Disc Thickness	5.0 mm (service limit 4.5 mm)
Brake Fluid	DOT 4
Tire Size (Front/Rear)	25 x 8-12 / 25 x 10-12
Tire Pressure	20 kPa (2.9 psi) for normal load

Service: Brake pad replacement, disc inspection, brake fluid bleeding.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine does not start	Fuel, spark, compression	Check fuel supply, spark plug, compression (standard 9.5 kg/cm²).
Poor performance	Clogged air filter, carburetor	Clean/replace air filter; inspect carburetor jets.
Overheating	Low coolant, clogged radiator	Check coolant level; clean radiator fins; test thermostat.
Transmission slippage	Worn drive belt, improper adjustment	Inspect drive belt; adjust belt tension.
Electrical failure	Blown fuse, bad battery	Check fuses; test battery voltage (12.8V fully charged).

Note: Refer to detailed troubleshooting charts in manual for systematic diagnosis.

Specifications

Model: Yamaha Grizzly 660 (YFM660F)
Engine Type: 660cc, 4-stroke, SOHC, liquid-cooled
Bore x Stroke: 102.0 mm x 80.5 mm
Compression Ratio: 9.5:1
Fuel System: Mikuni BSR40 carburetor
Transmission: Ultramatic automatic V-belt
Drive System: On-Command 2WD/4WD with diff lock
Suspension Front/Rear: Independent double wishbone / Swingarm
Brakes Front/Rear: Dual hydraulic disc / Single hydraulic disc
Tires Front/Rear: AT25 x 8-12 / AT25 x 10-12
Dry Weight: 265 kg (584 lb)
Fuel Capacity: 18.5 L (4.9 US gal)
Dimensions (LxWxH): 2115 mm x 1165 mm x 1220 mm

Service Contact: Authorized Yamaha dealer or Yamaha Motor Corporation, USA.