The 2004 Buell Firebolt, chassis codes XB9R and XB12R, represents a significant chapter in sportbike engineering, born from the innovative spirit of Erik Buell. Known for its unique V-twin, air-cooled Thunderstorm engines, offering 984cc or 1203cc displacement and impressive horsepower figures, the Firebolt is characterized by its rigid aluminum frame, which cleverly incorporates the fuel reservoir. This design, along with the revolutionary ZTL (Zero Torsional Load) front braking system featuring a massive 375mm floating disc and 6-piston caliper, contributes to its agile handling and distinctive performance. The Firebolt's heritage lies in its focus on sportbike performance, integrating advanced engineering for a thrilling riding experience. This comprehensive English-language service manual provides extensive workshop repair coverage for the 2004 Buell Firebolt. It details scheduled maintenance procedures, including oil and spark plug replacement, and covers all major systems such as the chassis, engine, fuel system, starter, drive transmission, and electrical components. With step-by-step repair instructions, troubleshooting guides, and essential technical specifications, this manual is an indispensable resource for Firebolt XB9R/XB12R owners, DIY enthusiasts, and independent repair shops. It empowers users to maintain and repair their motorcycles effectively, ensuring optimal performance and longevity.