Harley Knucklehead Parts

Harley Knucklehead Parts

The writing was the on the wall. The future of Harley V-Twin engines had to be in overhead valves. And in 1936, the Harley Knucklehead was born. With their competitors producing more powerful engines with overhead valves, Harley knew they needed to evolve to be more competitive. The MOCO had experimented with overhead valves on special projects before, but the Knucklehead was their first attempt at pushing a production OHV. The engine received its name in the 60’s from the fans who noticed that the rocker boxes looked like a clenched fist. It first appeared in the Harley E series motorcycles in ’36 as a 61ci engine.

The E engine was a large step-up from the previous Big Twin. The big advancement that came about with the Knuck’ was the overhead valves. This allowed the engines to make more power without excessive heat affecting the cylinders. It also featured a recirculating oil system instead of the total-loss system. This was necessary as power increased and more moving parts were added to the engine. The dry sump system allowed for more consistent engine temps and made the motorcycle more dependable on longer rides. In ’41, the Knucklehead grew from 61ci to 74ci. The 74ci Knuckleheads were used in the original FL motorcycles.

Along with the introduction of overhead valves, the E series motorcycles introduced other technical advancements as well. A double-cradle frame held the mill from both sides. The E bikes had a far superior clutch as well as a four-speed transmission, which helped put the increased power down. Up front, a springer fork is used. The styling of these bikes has continued to be treasured throughout the decades since they have been produced. The E series motorcycles were a favorite during the 60’s chopper era.

Though the Knucklehead engines were a success performance-wise, their production was hindered by the advancement of WWII and America’s increasing involvement. Many resources went to wartime manufacturing and bikes available to civilians severely dropped. The Flathead was used more for military motorcycles as well, which also affected the number of Knucklehead bikes produced. The numbers rebounded after the war, but in 1948, Harley-Davidson released the Panhead engine.

Being a vintage Harley engine, there aren’t a ton of new aftermarket parts still being made for the Knucklehead. That being said, they are out there and Dennis Kirk carries a great selection of parts. With them, you are able to bring new life to your old OHV Harley. And when your order is over $89, we will ship it to you for free. Use the Ride Selector at the top of the page to find all of the parts that fit your specific bike. Also, feel free to contact our knowledgeable Tech Team if you have any questions on which parts are best for you and your machine.