This comprehensive repair manual covers all aspects of maintaining and repairing your Harley Davidson Big Twin Knucklehead/Flathead motorcycle from 1940 to 1947. It's a valuable resource for any owner or mechanic looking to keep their classic Harley in top condition. Inside the manual, you'll find detailed instructions and diagrams covering everything from initial servicing and engine lubrication to complete engine overhauls and electrical system troubleshooting. You'll learn how to service the carburetor, transmission, wheels and hubs, fork, frame, and handlebars, and even get information on sidecar maintenance. The manual also includes a comprehensive troubleshooting chart, a detailed index, and numerous photographs and illustrations to help you visualize each step.

The Harley-Davidson Knucklehead, produced from 1936 to 1947, represents a significant milestone in motorcycle history. This iconic engine design, characterized by its distinctive "knuckle" shaped rocker arms, revolutionized Harley-Davidson's performance and style. The Knucklehead engine, a 45-cubic-inch (740 cc) V-twin, offered substantial improvements over its predecessor, the Flathead. With advancements like a new cylinder head design incorporating a hemispherical combustion chamber, improved valve timing, and a more efficient oiling system, the Knucklehead boasted increased power and smoother operation. Its distinctive styling, featuring a chrome-plated engine and streamlined design, solidified its place as a symbol of the "golden age" of American motorcycling.

Beyond its mechanical innovations, the Knucklehead became a cultural icon, inspiring generations of riders and contributing to the rise of motorcycle culture. The engine's distinctive sound and its association with postwar Americana made it a mainstay in popular culture, appearing in countless movies, television shows, and music videos. Despite its discontinuation in 1947, the Knucklehead remains a highly sought-after classic. Its timeless design, historical significance, and enduring performance continue to make it a coveted collector's item and a symbol of Harley-Davidson's heritage. The "Big Twins" Knucklehead and Flathead manuals provide valuable information for enthusiasts seeking to maintain and restore these iconic machines, ensuring their continued legacy.