This manual covers the KTM LC4 models, including the 400 and 660 variants, produced between 1998 and 2005. The LC4 platform is recognized for its powerful single-cylinder, liquid-cooled engine, featuring DOHC and four valves per cylinder, delivering robust performance suitable for diverse riding conditions. KTM's heritage in competition and off-road riding is evident in the LC4's durable construction, including a chromoly steel trellis frame and capable suspension systems. These motorcycles are designed for versatility, appealing to riders seeking a potent and reliable machine for both on-road and off-road adventures.

This workshop service and repair manual provides comprehensive guidance for owners and technicians. It details engine disassembly and servicing, transmission and clutch operation, chassis components, and electrical systems, including wiring diagrams. Essential maintenance procedures, such as oil changes, filter replacements, and valve adjustments, are clearly outlined, alongside detailed repair instructions for engine rebuilds, carburetor overhauls, and component replacements. Troubleshooting guides are included to diagnose and resolve common issues, ensuring the longevity and optimal performance of your KTM LC4.