This comprehensive service repair manual provides the technical information needed to properly repair your 1940-1947 Harley Davidson Big Twin Knucklehead or Flathead motorcycle. The manual covers all aspects of servicing these classic machines, from basic maintenance procedures to complete engine overhauls. Detailed diagrams and illustrations accompany clear step-by-step instructions, simplifying every repair procedure. The manual includes a trouble chart for quick diagnosis, information on initial servicing of a new motorcycle, engine lubrication and overhaul, electrical system troubleshooting and repair, carburetor servicing, transmission maintenance, wheel and hub repair, fork, frame, and handle maintenance, and even sidecar servicing. A detailed index ensures easy navigation and quick access to the information you need. Whether you're a seasoned mechanic or a dedicated owner looking to tackle your own repairs, this manual is an essential resource for keeping your classic Harley Davidson running in top condition.

## The Harley Davidson Big Twin Knucklehead and Flathead: A Legacy of Power and Style The 1940-1947 Harley Davidson Big Twin Knucklehead and Flathead motorcycles represented a turning point in the history of the brand, marking the transition from the iconic "Knucklehead" engine to the newly developed, yet equally powerful, "Flathead" powerplant. Both engines were V-twin configurations, offering a unique and unmistakable rumble, but with distinct characteristics. The Knucklehead, with its distinctive valve rocker covers resembling knuckles, was known for its smooth operation and impressive power for its time. This engine revolutionized Harley Davidson, ushering in a new era of performance and style. The Flathead, while retaining the V-twin configuration, employed a simpler, more robust design with enclosed rocker arms. Despite its comparatively lower horsepower, the Flathead possessed an impressive torque, making it a capable cruiser and workhorse for its time. Both the Knucklehead and Flathead equipped Big Twins boasted a classic design, featuring a rigid frame and a distinctive, low-slung profile. The chrome accents, iconic peanut fuel tank, and the distinctive "panhead" style headlight contributed to their timeless appeal. These motorcycles were offered in various configurations, from the basic "Roadster" model to the luxurious "Duo-Glide" touring bike. Their robust construction and reputation for reliability made them popular among riders of all backgrounds, from everyday commuters to seasoned adventurers. While the 1940s saw limited production due to World War II, the Big Twin Knucklehead and Flathead motorcycles cemented their legacy as robust and stylish machines that captured the spirit of American freedom and the enduring appeal of classic motorcycle design.