The Yamaha YFZ 450 is a high-performance sport All-Terrain Vehicle (ATV) renowned for its potent 450cc, 4-stroke, 5-valve DOHC liquid-cooled engine and agile handling. Introduced in 2004, it quickly established Yamaha as a leader in the sport ATV market, favored by recreational riders, racers, and off-road enthusiasts for its powerful performance and aggressive styling. This model, covering the 2004 and 2005 production years, features a lightweight chassis, independent front suspension, and a monoshock rear suspension, making it a formidable machine for demanding terrain. This comprehensive factory service manual provides in-depth coverage for the Yamaha YFZ 450, encompassing all aspects of its maintenance and repair. It details procedures for the engine, transmission, chassis, suspension, brakes, and electrical system, along with troubleshooting guides and technical specifications. The manual is designed to assist owners, mechanics, and technicians in performing routine maintenance, diagnosing issues, and completing complex repairs, ensuring the YFZ 450 maintains its peak performance and reliability. 🏷️ Basic Information Identification Make: Yamaha Model: YFZ 450 Vehicle Type: All-Terrain Vehicle (ATV) Model Years Covered: 2004, 2005 Product Name: Yamaha YFZ 450 2004-2005 ATV Service Factory Repair Manual PDF Download Codes Chassis Code General: Often identified by VIN starting with JY4 Engine Code General: 4-stroke, 5-valve, DOHC, Liquid-cooled, Single-cylinder 👋 Introduction Market Position Segment: High-performance sport ATV Target Audience: Recreational riders, racers, off-road enthusiasts Competitive Analysis Key Competitors: Honda TRX450R, Suzuki LT-R450, Kawasaki KFX450R Key Features Vehicle Highlight: Renowned for its powerful engine and agile handling, establishing Yamaha as a leader in the sport ATV market. Manual Highlight: Provides essential information for maintaining peak performance and undertaking complex repairs on this iconic ATV. 📋 Manual Details Coverage Areas Scope: Comprehensive service and repair Specific Sections: Engine, transmission, chassis, suspension, brakes, electrical system, body, troubleshooting Page Count Estimated Pages: 300-500 pages (typical for this era of service manual) Manual Type Type: Factory Service Manual / Repair Manual Language Language: English Format Format: PDF Download 📖 Manual Coverage Systems Covered Powertrain: Engine disassembly, assembly, tuning, cooling system, lubrication system, fuel system, exhaust system Drivetrain: Transmission operation, clutch service, final drive, chain adjustment Chassis And Suspension: Frame inspection, front suspension (A-arms, steering components), rear suspension (swingarm, shock absorber), wheel bearings, steering system Brakes: Hydraulic brake system (front and rear), caliper service, master cylinder service, brake fluid specifications, bleeding procedures Electrical System: Ignition system, lighting, starting system, charging system, battery maintenance, wiring diagrams, diagnostic procedures Body And Trim: Plastic body panel removal/installation, seat, fenders, handle bar assembly Procedures Included Maintenance: Oil changes, filter replacement, air filter cleaning/replacement, spark plug replacement, chain lubrication, brake adjustments Troubleshooting: Step-by-step diagnostic flowcharts for common issues (e.g., starting problems, poor performance, electrical faults) Repair: Detailed procedures for component disassembly, inspection, repair, and reassembly Rebuilding: Engine rebuild procedures, carburetor overhaul Technical Data: Torque specifications for all fasteners, valve clearances, timing procedures Technical Depth Depth: Factory-level detail, suitable for professional technicians and experienced DIY enthusiasts Diagnostics: Includes methods for diagnosing electrical and mechanical issues, often referencing specific tool usage 📊 Manual Specifications File Format File Type: PDF Searchability: Text-searchable (typically) Print Quality Image Resolution: High resolution for clear diagrams and illustrations Binding Type Binding: N/A (PDF Download) Paper Type Paper: N/A (PDF Download) ⚙️ Engine Specifications Primary Engine Engine Type: 4-stroke, DOHC, 5-valve cylinder head Displacement: 449 cc Bore X Stroke: 95.0 mm x 63.1 mm Compression Ratio: 11.9:1 Cooling System: Liquid-cooled Performance Horsepower Approx: Approximately 40-45 hp (claimed) Torque Approx: Approximately 40 Nm (claimed) Fuel System Fuel Delivery: Mikuni BSR37 carburetor (or similar high-performance carb) Fuel Type: Unleaded gasoline, minimum 87 octane (AKI) Lubrication Oil Type: Yamalube 4-stroke motorcycle oil or equivalent API SG or higher, JASO MA certified, SAE 10W-40 or 20W-50 depending on temperature Oil Capacity W Filter: Approx. 2.1 L (2.2 US qt) Ignition Ignition System: TCI (Transistor Controlled Ignition) Spark Plug Type: NGK CR9EIX or equivalent (Iridium recommended) 🔧 Transmission Standard Transmission Type: Constant mesh, 5-speed manual with reverse Clutch Type: Wet, multiple-disc Final Drive: O-ring sealed chain drive Features Gear Ratios: Detailed in manual (typically includes 1st through 5th gear ratios and reverse) Transmission Oil Type: Yamalube 4-stroke motorcycle oil or equivalent API SG or higher, JASO MA certified, SAE 10W-40 or 20W-50 (same as engine oil) Transmission Oil Capacity: Approx. 0.8 L (0.85 US qt) 📐 Dimensions Exterior Length: Approx. 1830 mm (72.0 in) Width: Approx. 1215 mm (47.8 in) Height: Approx. 1040 mm (40.9 in) Wheelbase: Approx. 1280 mm (50.4 in) Ground Clearance: Approx. 250 mm (9.8 in) Weights Curb Weight: Approx. 177 kg (390 lbs) Fuel Tank Capacity: Approx. 10 L (2.6 US gal) Dimensions Unit Unit Of Measure: Metric and Imperial (provided in manual) 🛡️ Safety Features Ratings Safety Standards: Meets all applicable US EPA emission standards. Designed for off-road use only. Active Features Braking System: Dual hydraulic disc brakes (front), Single hydraulic disc brake...