2005 Yamaha Grizzly 660 Service Manual

The 2005 Yamaha Grizzly 660 is a 4x4 all-terrain vehicle (ATV) powered by 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 swingarm rear suspension. This service manual provides comprehensive information for maintenance, troubleshooting, and repair. Below are key sections covering safety, specifications, periodic maintenance, engine service, chassis, electrical systems, and troubleshooting.

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

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) and model label locations.
General Precautions	Work in a well-ventilated area. Use proper tools. Support vehicle securely.
Safety Symbols	Meaning of WARNING, CAUTION, and NOTE labels used throughout manual.
Lift Points	Proper locations for jack stands or ATV lift.
Torque Specifications	Importance of using correct torque values during reassembly.

Specifications

Model: YFM66FPA (Grizzly 660 4x4 Auto.)
Engine Type: Liquid-cooled, 4-stroke, SOHC, 4-valve
Displacement: 660 cm³
Bore x Stroke: 102.0 mm x 80.5 mm
Compression Ratio: 9.5:1
Fuel System: Mikuni BSR42 carburetor
Starting System: Electric starter
Transmission: Yamaha Ultramatic (V-belt automatic)
Drive System: On-Command 2WD/4WD with diff lock
Suspension Front/Rear: Independent double wishbone / Swingarm
Brakes Front/Rear: Dual hydraulic disc / Sealed wet multi-disc
Tires: AT25 x 8-12 front, AT25 x 10-12 rear
Fuel Capacity: 5.3 US gal (20.0 L)
Oil Capacity: 3.2 qt (3.0 L) with filter change

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: Check level and change per schedule (every 100 hours or 6 months). Use Yamalube 4 (10W-30) or equivalent.
Oil Filter: Replace with every oil change.
Air Filter: Clean foam element regularly (every 20-40 hours). Service more often in dusty conditions.
Spark Plug: NGK DR8EA. Check gap (0.028–0.031 in / 0.7–0.8 mm) and condition.
Drive Chain: Check tension and lubricate every 20 hours.
Brake Fluid: Check level in reservoirs. Replace fluid every 2 years.
Differential Oil: Front and rear. Check and change per schedule.
Grease Points: Lubricate suspension pivots, steering stem bearings.

WARNING! Engine and exhaust are hot after operation. Allow to cool before servicing.

Fuel System & Throttle

Carburetor adjustment and throttle cable free play are critical for safe operation.

Carburetor (Mikuni BSR42): Idle speed: 1400 ± 100 rpm. Pilot screw initial setting: 2-1/4 turns out. Throttle cable free play: 0.20–0.28 in (5–7 mm).

Fuel Tank: Capacity 5.3 gal. Remove for access to top of engine. Always relieve fuel pressure and disconnect battery before service.

Fuel Filter: Inline filter. Replace if clogged.

CAUTION! Gasoline is extremely flammable. No sparks or open flames.

Engine & Transmission

Detailed procedures for cylinder head, valve adjustment, piston, crankshaft, and clutch service.

Valve Clearance: Check and adjust when cold. Intake: 0.004–0.006 in (0.10–0.15 mm). Exhaust: 0.008–0.010 in (0.20–0.25 mm).
Cylinder Head Removal: Drain coolant, remove intake/exhaust, disconnect cables/hoses.
Piston & Rings: Standard piston size: 102.000–102.015 mm. Ring end gap specifications provided.
Clutch (Ultramatic): Service driven clutch, drive clutch (primary sheave), and V-belt. Belt width specification: 1.18 in (30 mm) minimum.
Oil Pump: Driven by crankshaft. Check for proper priming.

Tip: Organize bolts and label hoses during disassembly.

Chassis & Suspension

Front and rear suspension service, steering, and frame.

Front Suspension: Independent double wishbone with shock absorbers. Check bushings, ball joints, and shock condition.

Rear Suspension: Swingarm with single shock. Preload adjustable. Check pivot bearings and swingarm for play.

Steering: Handlebar removal, steering stem bearing adjustment and repack.

Wheels & Tires: Torque lug nuts to 65 Nm (47 ft-lb). Tire pressure: Front 3.6 psi (25 kPa), Rear 3.6 psi (25 kPa) for standard load.

Electrical System

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

Component	Specification/Test
Battery	YTZ7S (12V, 6.3Ah). Charging voltage: 14.1–14.9V @ 5000 rpm.
Starter Motor	Brush length min: 0.35 in (9.0 mm). Commutator undercut depth: 0.02 in (0.5 mm).
Starter Relay	Click test; continuity check.
AC Magneto	Charging coil resistance: 0.36–0.54 Ω (20°C). Lighting coil resistance: 0.24–0.36 Ω.
CDI Unit	Diagnosis by substitution or using special tester.
Fuses	Main 30A, Headlight 15A, Signal 10A, Ignition 10A.

Brake System

Hydraulic disc brakes front, sealed wet multi-disc brake rear.

Front Brakes: Dual-piston calipers. Pad wear limit: 0.04 in (1.0 mm). Rotor thickness limit: 0.16 in (4.0 mm).
Rear Brake: Foot-operated, sealed system. Service requires disassembly of rear gearcase.
Brake Fluid: Use DOT 4. Bleed system to remove air.
Brake Lever/Pedal Free Play: Adjust as needed.

WARNING! Brake fluid damages paint. Handle carefully.

Drive System

On-Command 2WD/4WD system, front and rear differentials, driveshafts.

On-Command System: Electric shift motor engages front differential. Check operation, wiring, and motor.

Front Differential: Oil capacity: 0.42 qt (0.4 L). Use API GL-5 Hypoid gear oil SAE 80W-90.

Rear Differential/Gearcase: Oil capacity: 1.06 qt (1.0 L). Includes rear brake assembly.

Driveshafts: CV joints. Check boots for tears and repack grease if necessary.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine does not start	Weak battery, faulty starter, fuel issue, no spark	Check battery voltage, fuel flow, spark plug, sidestand switch, neutral switch.
Engine starts but dies	Clogged fuel filter, dirty carburetor, bad gas	Clean carburetor jets, replace fuel, check vacuum lines.
Poor performance/loss of power	Clogged air filter, restricted exhaust, worn clutch	Service air filter, check spark arrestor, measure clutch belt width.
Overheating	Low coolant, clogged radiator, faulty thermostat	Check coolant level and condition, clean radiator fins, test thermostat.
Electrical failure (no lights)	Blown fuse, bad bulb, faulty switch	Check fuses, test bulbs with multimeter, inspect switches.
4WD not engaging	Faulty switch, shift motor, wiring	Test switch continuity, listen for motor click, check connections.
Excessive vibration	Unbalanced tires, bent rim, worn U-joint	Inspect tires and rims, check driveshaft CV joints.
Brakes dragging or weak	Contaminated pads, air in lines, worn master cylinder	Clean or replace pads, bleed brakes, inspect master cylinder seals.

Reset ECU: Disconnect battery for 10 minutes to clear adaptive memory.

Wiring Diagrams

Complete color-coded wiring diagrams for the entire electrical system are included in the full manual. Refer to diagrams for wire colors, connector locations, and ground points when diagnosing electrical faults.

Note: Always use a multimeter for voltage and continuity checks. Ensure all connections are clean and tight.