This manual covers the 125 SX, 200 SX, and ECX models produced between 1999 and 2003. These competition off-road motorcycles are renowned for their strong performance, aggressive styling, and competitive edge in motocross, reflecting a deep racing heritage. The two-stroke, single-cylinder engines, available in 125cc and 200cc variants, are liquid-cooled and feature robust construction designed for demanding off-road use. With a 6-speed manual transmission and advanced suspension systems, these models were built to excel in motocross racing environments.

This comprehensive service repair workshop manual provides detailed information essential for the maintenance and repair of your 125 SX, 200 SX, or ECX. It covers critical areas including complete engine overhaul, fuel system (carburetor), ignition system, transmission, clutch, and basic chassis and electrical systems relevant to engine operation. The manual includes step-by-step procedures for routine maintenance, troubleshooting common issues, engine rebuilds, and component testing, ensuring that owners, mechanics, and technicians have the knowledge to keep these performance machines in optimal condition.