The Firebolt XB12R, a 2005 model, stands as a testament to innovative American sportbike engineering. Developed by the Motorcycle Company, known for its racing heritage and unique design philosophy, this model distinguished itself with a torque-rich, air-cooled 1203 cc V-twin Thunderstorm engine. Its performance-oriented design incorporated key features such as fuel-in-frame technology, a Uniplanar powertrain mounting system for reduced vibration, and an under-seat exhaust, all contributing to exceptional mass centralization and agile handling. The Firebolt XB12R offered a distinctive riding experience, competing in the performance sportbike segment with its aggressive styling and focus on rider engagement. This workshop service manual provides comprehensive repair and service information for the 2005 Firebolt XB12R. Covering a vast array of systems including the engine mechanicals, fuel and ignition systems, electrical components, chassis, suspension, and brakes, it details procedures for removal, installation, disassembly, assembly, adjustment, and repair. The manual is designed to assist owners, mechanics, and technicians by offering systematic troubleshooting, diagnostic procedures, maintenance schedules, torque specifications, and wear limits, supported by extensive pictorial diagrams and exploded views for clarity.