This manual covers the Knucklehead Flathead motorcycles, including EL, FL, U, and UL models, produced between 1940 and 1947. These iconic V-twin motorcycles, powered by 61ci (EL) or 74ci (E, F, FL, U, UL) overhead valve engines, are celebrated for their robust engineering and distinctive design. Known for their torque-focused performance and reliability, the Knucklehead series represents a significant era in motorcycle history, preceding the Panhead models. This resource is essential for owners and restorers seeking to maintain or rebuild these highly collectible machines, offering comprehensive details that surpass generic workshop guides.

This comprehensive service repair manual provides in-depth information for the maintenance, troubleshooting, and rebuilding of your Knucklehead Flathead motorcycle. It covers all major systems, including the engine, fuel, ignition, electrical, transmission, drivetrain, brakes, suspension, and chassis. Detailed procedures for routine maintenance, carburetor adjustment, ignition timing, and complete engine teardown and reassembly are included, alongside extensive troubleshooting guidance for common issues. The manual is designed to assist professional mechanics, experienced home mechanics, and dedicated restorers in ensuring the optimal performance and longevity of these classic motorcycles.