This comprehensive service and repair manual for Harley Davidson Knucklehead and Flathead motorcycles, covering models from 1940 to 1947, provides detailed instructions for servicing, repairing, restoring, maintaining, rebuilding, and diagnosing your motorcycle. The manual includes detailed information on all aspects of these models, including the O.H.V engine (61 cu. in. (1000 c.c) and 74 Cu.In. (1200 c.c)) and the Side Valve engine (74 Cu.IN. (1200 c.c) and 80 Cu. In. (1300 c.c)). The manual is illustrated with clear step-by-step instructions and features a trouble chart, information on initial servicing of a new motorcycle, engine lubrication, engine overhaul, the electrical system, servicing the carburetor, transmission, wheels and hubs, fork, frame and handle, and sidecar. The detailed index makes it easy to find the information you need. This manual is the same one used by professional technicians and mechanics, offering the complete step-by-step information needed for every repair and troubleshooting procedure.

The Harley-Davidson Knucklehead and Flathead motorcycles, produced from 1940 to 1947, represent a significant period in the iconic American motorcycle manufacturer's history. These models were renowned for their robust construction, powerful engines, and enduring legacy. The Knucklehead, with its distinctive "knuckle" rocker arm design, was introduced in 1936 and quickly gained popularity for its improved performance and smoother operation compared to the previous OHV models. The Flathead, a more affordable and accessible option, featured a single overhead valve engine and remained in production until 1948. Both models played a crucial role in solidifying Harley-Davidson's reputation as a leading motorcycle manufacturer during the pre-war and post-war eras. The 1940-1947 Knucklehead and Flathead models offered a range of unique features that contributed to their success. The Knucklehead's 45 cubic inch engine, featuring a dual overhead camshaft and a 5-speed transmission, delivered impressive power and speed for its time. The Flathead, with its 61 cubic inch engine, provided a more balanced blend of power and fuel efficiency. Both models featured a rigid frame, a characteristic common to motorcycles of that era, which provided strength and durability but resulted in a less comfortable ride compared to later models with spring-based suspension systems. These motorcycles played a vital role in supporting the war effort, serving as transportation for military personnel and aiding in various logistical tasks. The 1940-1947 Knucklehead and Flathead models represented a peak in American motorcycle engineering, paving the way for future advancements and establishing a lasting legacy in the world of motorcycling.