2006 Yamaha Grizzly 660 Service Manual

The 2006 Yamaha Grizzly 660 is a four-wheel drive all-terrain vehicle (ATV) featuring a 660cc liquid-cooled, SOHC, 4-stroke engine with Ultramatic automatic transmission, On-Command 2WD/4WD with differential lock, independent double wishbone front suspension, and a fully sealed wet brake system. This manual provides comprehensive service, maintenance, and repair information for owners and technicians. Below are key sections covering safety, specifications, periodic maintenance, engine service, chassis, electrical, troubleshooting, and warranty.

1. General Information & Safety 2. Specifications 3. Periodic Maintenance 4. Engine 5. Chassis 6. Electrical System 7. Troubleshooting 8. Lubrication & Fluids 9. Storage & Winterization 10. Warranty & Support

General Information & Safety

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

Safety Symbol	Meaning
WARNING!	Indicates a potential hazard that could result in serious injury or death.
CAUTION!	Indicates a potential hazard that could result in minor injury or product damage.
NOTE	Provides helpful information and tips for proper service.

WARNING! Always disconnect the battery before performing electrical service. Use proper lifting equipment when raising the ATV. Wear appropriate safety gear including eye protection.

Specifications

Model: 2006 Yamaha Grizzly 660 (YFM66FGP)
Engine Type: 660cc, liquid-cooled, SOHC, 4-stroke, single cylinder
Bore x Stroke: 102.0 mm x 80.5 mm
Compression Ratio: 9.2:1
Fuel System: Mikuni BSR42 carburetor
Transmission: Yamaha Ultramatic automatic V-belt with all-wheel engine braking
Drive System: On-Command 2WD/4WD with differential lock
Suspension Front/Rear: Independent double wishbone / Swingarm
Brakes Front/Rear: Dual hydraulic disc / Sealed wet multi-disc brake
Tires: AT25 x 8-12 front, AT25 x 10-12 rear
Fuel Capacity: 4.8 gal (18.2 L)
Dry Weight: 600 lb (272 kg)

Periodic Maintenance

Regular maintenance ensures optimal performance and longevity. Refer to the maintenance schedule in the owner's manual.

Pre-ride inspection: Check tires, brakes, lights, controls, and fluid levels.
Engine oil & filter: Change every 100 hours or 6 months (whichever comes first). Use Yamalube 4 (10W-30) or equivalent.
Air filter: Clean every 20-50 hours; replace if damaged.
Spark plug: NGK CR8E; check gap (0.028-0.031 in) and replace every 100 hours.
Drive belt: Inspect for wear/cracks every 200 hours.
Brake fluid: Check level and condition; replace every 2 years.
Differential oil: Change front and rear every 200 hours.

CAUTION! Use only recommended fluids and parts. Torque fasteners to specified values.

Engine

Service procedures for the 660cc engine, including top end, cylinder head, piston, crankshaft, and lubrication system.

Component	Specification/Torque
Cylinder Head Bolt	37 ft-lb (50 Nm) in sequence
Spark Plug	13 ft-lb (18 Nm)
Oil Drain Plug	20 ft-lb (27 Nm)
Valve Clearance (Cold)	IN: 0.004-0.006 in (0.10-0.15 mm), EX: 0.008-0.010 in (0.20-0.25 mm)
Idle Speed	1400 ± 100 rpm

WARNING! Allow engine to cool before servicing. Ensure all gaskets are replaced during reassembly.

Chassis

Includes frame, suspension, steering, brakes, wheels, and tires.

Front Suspension: Inspect A-arms, bushings, and shocks for wear. Torque pivot bolts to 65 ft-lb (88 Nm).
Rear Suspension: Check swingarm pivot and bearing play. Lubricate with grease every 100 hours.
Brakes: Pad thickness minimum 0.12 in (3 mm). Bleed system if spongy. Use DOT 4 brake fluid.
Steering: Check for free play; adjust if necessary. Torque steering stem nut to 65 ft-lb (88 Nm).
Tires: Recommended pressure: 3.6 psi (25 kPa) front, 3.6 psi (25 kPa) rear for standard load.

NOTE: After servicing suspension or steering, test ride at low speed to verify operation.

Electrical System

Battery, charging system, starter, lighting, switches, and wiring diagrams.

Battery: YTX20L-BS, 12V 18Ah. Keep terminals clean and tight.
Charging Voltage: 14.0-14.5V at 5000 rpm.
Fuses: Main 30A, Headlight 15A, Signal 10A. Located under seat.
Bulbs: Headlight 12V 35/35W, Brake/Tail 12V 21/5W.

CAUTION! Disconnect negative battery terminal first. Avoid short circuits.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Weak battery, faulty spark plug, clogged fuel filter, carburetor issue	Check battery voltage, spark, fuel flow. Clean carburetor jets.
Poor performance/loss of power	Dirty air filter, restricted exhaust, worn drive belt, valve adjustment	Service air filter, check exhaust for blockage, inspect drive belt, adjust valves.
Overheating	Low coolant, clogged radiator, faulty thermostat, water pump	Check coolant level and condition, clean radiator fins, test thermostat.
Transmission slipping/no drive	Worn drive belt, improper belt adjustment, worn sheaves	Inspect belt and sheaves for wear. Adjust belt deflection.
Electrical failure (no lights)	Blown fuse, bad ground connection, faulty switch	Check fuses, inspect wiring harness and connectors.
4WD not engaging	Faulty switch, damaged wiring, differential actuator issue	Test switch operation, check actuator motor and connections.

Lubrication & Fluids

Recommended fluids and capacities.

System	Fluid Type	Capacity
Engine Crankcase	Yamalube 4 (SAE 10W-30) or equivalent API SG or higher	3.2 qt (3.0 L) with filter change
Front Differential	SAE 80W-90 GL-5 Gear Oil	0.42 qt (0.4 L)
Rear Differential	SAE 80W-90 GL-5 Gear Oil	0.53 qt (0.5 L)
Cooling System	Yamaha Coolant or high-quality ethylene glycol antifreeze	1.8 qt (1.7 L)
Brake System	DOT 4 Brake Fluid	As required

WARNING! Do not mix different types of coolant or gear oil. Dispose of used fluids properly.

Storage & Winterization

Proper procedures for storing the ATV for extended periods.

Clean the ATV thoroughly.
Change engine oil and filter.
Add fuel stabilizer and run engine for 5 minutes.
Remove spark plug, add a teaspoon of oil into cylinder, and crank engine slowly. Reinstall plug.
Inflate tires to recommended pressure and elevate off ground if possible.
Disconnect battery and store in a cool, dry place. Charge monthly.
Cover with a breathable cover.

Warranty & Support

Yamaha Motor Corporation, U.S.A. provides a limited warranty. See your dealer for details.

Contact Information:
Yamaha Customer Relations: 1-800-962-7926
Website: www.yamahamotorsports.com
For genuine parts and accessories, contact an authorized Yamaha dealer.

This manual is a supplement to the official Yamaha Service Manual. For complete procedures and torque specifications, refer to Yamaha publication LIT-11616-22-83.