This manual covers the KTM 990 Super Duke, a naked sportbike/hyperbike produced between 2003 and 2007, identified by its LC8 chassis code. Known for its aggressive styling and potent V-twin engine, the 990 Super Duke was a significant model in KTM's expansion into the streetbike market, building on its off-road heritage. It features a liquid-cooled, four-stroke, 999 cc V-twin engine with DOHC and electronic fuel injection, delivering approximately 110-116 horsepower. The bike is equipped with a 6-speed transmission, a hydraulically operated wet multi-plate clutch, and a steel trellis frame, offering sharp handling and a powerful riding experience. This workshop service repair manual provides comprehensive coverage for the KTM 990 Super Duke, detailing service, repair, maintenance, and troubleshooting procedures. It is designed to assist owners with basic mechanical skills and professional mechanics alike. The manual includes in-depth information on the engine, powertrain, chassis, suspension, brakes, and electrical systems, along with step-by-step instructions for routine maintenance, component overhauls, and electrical diagnostics. With detailed specifications, torque values, and diagnostic procedures, this manual empowers users to effectively maintain and repair their vehicle, ensuring optimal performance and longevity.