This manual covers the 2009 Yamaha WR450F, a high-performance off-road motorcycle designed for competition. Known for its lightweight aluminum bilateral beam frame, powerful liquid-cooled DOHC 4-stroke engine, and industry-leading KYB SSS front forks and rear shock, the WR450F is engineered for optimal rigidity, handling, and reliability. Its lineage stems from Yamaha's extensive experience in off-road racing, making it a formidable machine in its segment, often compared to key competitors like the KTM 450 EXC and Honda CRF450X.

This comprehensive service repair manual is designed to assist owners, mechanics, and technicians in maintaining and repairing the 2009 Yamaha WR450F. It details procedures for engine overhaul, cooling, fuel, ignition, and electrical systems, as well as transmission, drivetrain, suspension, brakes, chassis, and bodywork. The manual includes basic maintenance schedules, troubleshooting guides, repair instructions, rebuild procedures, and tuning adjustments, making it an invaluable resource for ensuring the optimal performance and longevity of this competition-grade off-road motorcycle.