This comprehensive service and repair manual is a valuable resource for anyone working on a 1998-2003 KTM 400-660 LC4 motorcycle. It provides detailed instructions and step-by-step diagrams for all workshop procedures, empowering you to tackle repairs and maintenance with confidence. The manual covers a wide range of topics, including: * **General Information:** Gain a thorough understanding of the KTM 400-660 LC4 engine, its components, and essential safety precautions. * **Engine Removal and Refitting:** Learn the proper techniques for removing and reinstalling the engine, ensuring a smooth and efficient process. * **Disassembly and Assembly:** Explore detailed instructions for disassembling and reassembling the engine, carefully addressing each component and its function. * **Component Servicing:** Find detailed guidance on servicing individual engine components, ensuring optimal performance and longevity. * **Electrical System:** Dive into the intricacies of the electrical system, including troubleshooting common issues and understanding wiring diagrams. * **Fuel System:** Understand the fuel system's operation, troubleshooting techniques, and proper maintenance procedures. * **Troubleshooting:** Access a comprehensive guide to identify and resolve common engine problems, enabling efficient diagnosis and repair. * **Technical Specifications:** Find essential technical specifications for your KTM 400-660 LC4 engine, ensuring accurate part identification and component selection. * **Periodic Maintenance Schedule:** Adhere to a recommended maintenance schedule to keep your motorcycle running smoothly and prevent potential issues. * **Wiring Diagrams:** Utilize detailed wiring diagrams to understand the electrical system's layout and connections, facilitating repairs and modifications. With this manual, you'll have access to everything you need to perform a wide range of repairs and maintenance tasks on your KTM 400-660 LC4, enabling you to save money and gain a deeper understanding of your machine.

The 1998-2003 KTM 400-660 LC4 engine, a workhorse in the realm of off-road motorcycles, graced a diverse range of models, each embodying KTM's commitment to performance and reliability. This liquid-cooled, single-cylinder engine, boasting a displacement ranging from 400cc to 660cc, powered various KTM models, including the popular EXC and Adventure series. The LC4 engine's reputation for durability and its ability to thrive in demanding off-road conditions made it a favorite among both recreational riders and professional racers. Its robust construction, featuring a forged crankshaft, Nikasil-coated cylinder, and a robust transmission, ensured longevity even under extreme stress. This engine's simplicity and user-friendliness allowed for relatively easy maintenance, further enhancing its appeal to both seasoned riders and newcomers. The 1998-2003 KTM 400-660 LC4 engine offered a unique blend of power and tractability. Its single-cylinder configuration delivered a smooth, linear power delivery, ideal for navigating challenging terrain. The engine's generous torque made it effortless to climb hills and maintain momentum in technical sections. Its light weight and compact design contributed to the motorcycles' exceptional handling, agility, and maneuverability. While the 400cc engine provided a playful and manageable experience, the larger 660cc variant offered a significant power advantage, allowing riders to tackle more demanding trails and competitions. Regardless of the displacement, the LC4 engine's inherent reliability and robust construction made it a testament to KTM's engineering prowess and a testament to its enduring legacy in the world of off-road motorcycling.