This manual covers the 450 EXC, 400 EXC, and 520 SX models from the production years 2000 through 2003. These high-performance off-road motorcycles are powered by the robust LC4 engine family, available in 400cc, 450cc, and 520cc displacements. Renowned for their powerful engines, lightweight chassis, and aggressive off-road performance, these motorcycles cater to competitive riders and serious enthusiasts. They have a strong heritage in motorsports, validating their capabilities in demanding conditions, and are manufactured in Austria.

This comprehensive service and repair manual provides detailed guidance for engine service and repair. It covers engine mechanicals, lubrication, cooling systems, fuel systems, ignition systems, and exhaust systems. The manual includes procedures for preventative maintenance, systematic troubleshooting, engine rebuilds, carburetor adjustments, and valve adjustments. It is designed to assist owners, mechanics, and technicians in maintaining and repairing these vehicles, offering advanced diagnostics and detailed repair complexity suitable for a wide range of skill levels.