Welcome to the comprehensive guide for the Yamaha YFM660 Grizzly, a high-performance utility All-Terrain Vehicle produced between 2001 and 2006. Renowned for its powerful 660cc engine, automatic transmission with selectable 4WD, and independent front suspension, the Grizzly 660 was designed for off-road enthusiasts, hunters, farmers, and recreational riders seeking capability and reliability. Its robust chassis, substantial cargo rack capacity, and comfortable ride made it a benchmark in its segment, comparable to leading models from other manufacturers. This workshop service manual provides detailed information essential for the maintenance, repair, and troubleshooting of your Yamaha YFM660 Grizzly. Covering all major systems including the powertrain, chassis, and electrical components, this manual offers step-by-step procedures for everything from routine maintenance, such as oil changes and filter replacements, to complex overhauls of the engine and transmission. It includes vital technical specifications, diagnostic guidance, and safety instructions, empowering owners and technicians to ensure the optimal performance and longevity of their vehicle. 🏷️ Basic Information Identification Make: Yamaha Model: YFM660 Model Designation: Grizzly 660 Codes Production Years: 2001, 2002, 2003, 2004, 2005, 2006 👋 Introduction Market Position Segment: High-performance Utility ATV (All-Terrain Vehicle) Target Audience: Off-road enthusiasts, hunters, farmers, recreational riders. Competitive Analysis Competitors: Honda Foreman/Rancher, Polaris Sportsman, Suzuki King Quad, Arctic Cat 500/650. Key Features Features Of Vehicle: Powerful 660cc engine, automatic transmission with selectable 4WD/2WD, independent front suspension, robust chassis, large cargo racks. 📋 Manual Details Coverage Areas Applicable Models: Yamaha YFM660 Grizzly 660 Applicable Years: 2001-2006 Page Count Estimated Pages: 400+ Manual Type Type: Workshop Service Manual / Repair Manual Language Language: English Format Format: PDF Download 📖 Manual Coverage Systems Covered Powertrain: Engine, Transmission, Drivetrain, Clutch, Carburetor/Fuel Injection Chassis: Suspension (Front & Rear), Steering, Brakes, Wheels, Tires Electrical: Ignition System, Lighting System, Starting System, Charging System, Wiring Diagrams, ECU/ECM Bodywork And Frame: Frame, Body Panels, Fenders, Racks, Seat Procedures Included Maintenance: Scheduled Maintenance, Oil Changes, Filter Replacements, Lubrication Points Troubleshooting: Diagnostic Procedures, Fault Finding Charts, Symptom-Based Diagnosis Repair And Rebuild: Engine Overhaul, Transmission Reassembly, Brake System Repair, Suspension Component Replacement Adjustments: Carburetor/Fuel Injection Tuning, Valve Clearances, Brake Adjustments Technical Depth Depth: Comprehensive: From basic checks and fluid changes to complete engine and transmission rebuilds. Includes detailed diagnostic procedures and specifications. 📊 Manual Specifications File Format File Type: PDF Searchable: Yes (typically, depending on PDF source) Print Quality Quality: High-resolution, suitable for printing Binding Type Binding: N/A (Digital Download) Paper Type Paper Type: N/A (Digital Download) ⚙️ Engine Specifications Primary Engine Type: 4-stroke, liquid-cooled, SOHC, 5-valve, single cylinder Displacement: 660 cc (40.3 cu. in.) Bore X Stroke: 100.0 mm x 84.0 mm (3.94 in x 3.31 in) Compression Ratio: 9.1:1 Performance Horsepower Estimated: ~40 HP @ 5500 RPM (Manufacturer specifications vary by region and tuning) Torque Estimated: ~45 lb-ft @ 4500 RPM (Manufacturer specifications vary by region and tuning) Fuel System Fuel Delivery: Mikuni BSR42 diaphragm-type carburetor (specific model may vary) Fuel Tank Capacity: 4.0 US gal (15.0 L) with 0.7 US gal (2.7 L) reserve Fuel Type: Unleaded gasoline, 87 octane or higher 🔧 Transmission Standard Type: Automatic (Yamaha Constant Velocity Transmission - YCVT) Drive Modes: Shaft drive; 2-wheel drive / 4-wheel drive (selectable) Gear Selection: Forward, Neutral, Reverse Features Engine Braking: Provides significant engine braking in lower gear ranges. Belt Material: Reinforced rubber composite V-belt. 📐 Dimensions Exterior Length: 81.7 in (2075 mm) Width: 44.5 in (1130 mm) Height: 45.1 in (1145 mm) Wheelbase: 50.8 in (1290 mm) Ground Clearance: 10.8 in (275 mm) Cargo Front Rack Capacity: 99 lbs (45 kg) Rear Rack Capacity: 187 lbs (85 kg) Weights Dry Weight: 562 lbs (255 kg) Wet Weight: 591 lbs (268 kg) Towing Capacity: 1102 lbs (500 kg) Front Tire Size: AT25x8-12 Rear Tire Size: AT25x10-12 Wheel Bolt Pattern: 4x110 mm 🛡️ Safety Features Ratings Atv Safety Standards: Complies with ANSI standards for recreational ATVs. Active Features Brakes Front: Dual hydraulic disc Brakes Rear: Dual hydraulic disc (inboard mounted) Parking Brake: Mechanical drum brake on rear drive shaft Passive Features Lighting: Dual 30W halogen headlights, 15W incandescent tail/brake light Hand Grips: High-density foam grips for reduced vibration. Seat: Comfortable, contoured seat for extended riding. 💡 Technology Features Infotainment Features: Basic instrumentation cluster (speedometer, odometer, trip meter, fuel gauge, 4WD indicator, etc.). No advanced infotainment features typical of modern vehicles. Driver Assistance Features: None (focus is on mechanical capability and driver control). Connectivity Features: None. 🔧 Maintenance Service Intervals Engine Oil Change: Every 1,000 km (600 miles) or 6 months, whichever comes first. Check oil level weekly. Air Filter Cleaning: Clean every 3 months or 1,000 km (600 miles). Replace as needed. Spark Plug Replacement: Replace every 12 months or 3,000 km (1,800 miles). Valve Clearance Check: Check every 6 months or 2,000 km (1,200 miles). Fluid Specifications Engine Oil Type: Yamalube 4 (SAE 10W-30) or equivalent API SG, JASO MA certified oil....