This manual covers the SX and EXC series off-road motorcycles, including models 250, 400, 450, and 525, produced between 2000 and 2007. These high-performance machines are renowned for their lightweight chassis, powerful engines, and advanced suspension, making them ideal for motocross racing and enduro riding. The 'Ready to Race' philosophy is evident in the engineering quality and competitive performance that defined these models during a period of significant technological advancement for the Austrian manufacturer. This comprehensive service and workshop manual provides detailed instructions for the maintenance, troubleshooting, and repair of your off-road motorcycle. It covers all essential systems, including engine mechanics, fuel and ignition systems, transmission, brakes, and suspension. You will find step-by-step procedures for routine maintenance, component overhauls, engine rebuilds, and electrical system diagnostics, complete with wiring diagrams and technical specifications. This manual is an indispensable resource for owners and technicians seeking to maintain optimal performance and reliability.