This manual covers the 2004 all-terrain vehicles (ATVs). A leader in powersports since 1954, these ATVs were engineered for robust utility and trail performance. The line is renowned for its durability and capability, and the 2004 models represent a refined iteration of this proven platform. Key features include a 4-stroke, liquid-cooled engine, an automatic Variable Transmission (PVT) with high/low range, and an On-Demand All-Wheel Drive system for superior traction. These ATVs are designed for a variety of tasks, from recreational trail riding to demanding work. This comprehensive factory service manual provides detailed information essential for the maintenance, repair, and troubleshooting of your 2004 400 or 500. It includes step-by-step instructions for all major systems, such as the engine, fuel system, body, steering, suspension, clutch, final drive, transmission, and electrical components, complete with wiring diagrams. With 335 pages of factory-level data, this manual empowers owners and technicians to perform everything from routine fluid changes and component servicing to complex engine and electrical diagnostics, ensuring the longevity and optimal performance of your ATV.