Knucklehead - the name describes a true legend and this engine design is without a doubt one of the important milestones in the history of Harley-Davidson. Introduced in the year 1936 the ohv-engined models in short time became synonyms for sporting, fast and reliable touring machines. Economically this layout proved to be a huge success for the Motor Company, too, because brand followers - and many others - quickly realized the outstanding qualities of this motorcycle. Design and technology of the Knucklehead turned out to be supremely sound and it became the prototype of all Milwaukee Big Twins, which significantly influenced all successive model groups down to the present day. The KN-Series engines by S&S closely resemble the appearance of a stock Knucklehead engine. However, numerous reforms enhance power, engine life, and reliability. The main improvement in design is the 1958-65 style flywheel assembly, which uses a splined sprocket shaft and a Timken sprocket shaft bearing on the drive side. This increased flywheel stability and strenght became necessary to handle the significantly increased power development. The rocker arm cover “tins” are another modern improvement. They are made from die-cast aluminum, and instead of being held in place by the valve guide, they are held down by valve spring pressure. A special gasket on the bottom of the lower “tin” provides a positive seal, and is much easier to service if needed, since the valve guides do not have to be pressed.

The selection includes 93” (1560 cc) engines with crankcases for early style chassis thru 1947, with 1955-64 tin primary and 1936-64 transmissions.

S&S KN-Series engines come completely assembled and ready to run with a electronic S&S Super Stock ignition system and Super E carburetor.