This manual provides comprehensive service and repair information for the KX125 and KX250 models, covering production years 2003 and 2004. These motorcycles are renowned for their performance and competitive edge in motocross, building on a rich motorsports heritage. The KX line has consistently been developed for optimal performance, making these machines highly regarded in their respective classes. This guide is designed to assist owners and mechanics in maintaining these powerful off-road competition motorcycles. The scope of this Service Repair Manual is extensive, detailing all essential aspects of the vehicle. It includes in-depth coverage of engine systems, drivetrain, chassis components, and the electrical system. Within these sections, you will find detailed step-by-step instructions for maintenance, repair, and diagnostic procedures, supported by numerous diagrams, illustrations, and photos. The manual also provides critical technical specifications, torque values, and component clearances necessary for accurate servicing. Its user-friendly format, featuring clickable menus and search functionality, ensures efficient navigation and access to the information needed to keep your KX125 or KX250 in peak condition.