This manual covers the KTM 400 LC4 and 660 LC4 models from 2004, renowned for their powerful LC4 liquid-cooled, four-stroke, single-cylinder engines. These motorcycles, with their robust chassis and off-road capabilities, were designed for enthusiast owners and featured strong performance for their segment, competing with models from brands like BMW, Honda, Yamaha, and Suzuki. The LC4 platform, with a history dating back to the 1980s, represents a mature iteration of KTM's engineering prowess, offering versatility that allowed for dual-sport or supermoto conversions.

This comprehensive workshop repair service manual provides detailed, A-Z coverage for all repairs and maintenance procedures specific to these KTM models. It includes in-depth instructions for engine overhaul, transmission and drivetrain service, suspension and steering maintenance, brake and wheel system repairs, and electrical system diagnostics. The manual also covers fuel and exhaust systems, bodywork, and frame components, along with troubleshooting guides and specific technical data, ensuring owners and technicians can effectively maintain and repair their vehicles.