This comprehensive workshop manual provides a detailed guide for servicing and repairing Harley Davidson Big Twins Knucklehead Flathead motorcycles manufactured from 1940 to 1947. It is an invaluable resource for both professional mechanics and dedicated enthusiasts, offering the same information used by Harley Davidson dealerships. The manual covers a wide range of topics, including engine maintenance, general motorcycle information, chassis components, lighting systems, clutch operation, suspension adjustments, braking systems, lubrication procedures, electrical systems, fuel system components, battery care, and much more. Detailed sections on engine overhaul and carburetor servicing are included, along with a comprehensive trouble chart for diagnosing common issues. The manual also features an extensive index for easy navigation and a dedicated section on sidecar maintenance, should you require it. This manual is your essential resource for keeping your classic Harley Davidson Knucklehead in top condition.

The Harley-Davidson Big Twin Knucklehead, a motorcycle engine that revolutionized the American motorcycle industry, was produced from 1936 to 1948. This iconic engine, known for its distinctive knuckle-shaped rocker arm covers, brought a significant leap in performance and reliability to Harley-Davidson motorcycles. The Knucklehead engine, a 45-cubic-inch (740 cc) V-twin, featured a number of innovative design elements, including a fully enclosed valve train, a single-piece cylinder head, and a new crankshaft design. This design resulted in a powerful and reliable engine that could handle the rigors of everyday riding while also providing thrilling performance. The Knucklehead's popularity soared, establishing itself as a cornerstone in the evolution of Harley-Davidson's legendary reputation.

The Knucklehead era marked a significant shift in Harley-Davidson's motorcycle design. The engine's introduction coincided with the burgeoning popularity of the "bobber" style, which involved customizing motorcycles for speed and performance. This trend further fueled the demand for the Knucklehead engine, as its power and reliability made it the perfect choice for building custom motorcycles. However, despite its enduring popularity, the Knucklehead engine was eventually phased out in favor of the more advanced Panhead engine in 1948. This marked the end of an era for Harley-Davidson, but the Knucklehead's legacy continues to inspire enthusiasts today. Its distinctive appearance, powerful performance, and historical significance continue to make it one of the most sought-after and cherished motorcycle engines ever produced.