The KN series engines are very close in appearance to the stock Knucklehead engine, but offer a number of modern features for more power, better engine life, and improved reliability Aside from the much larger 93" displacement, the main improvement in design is the 1958-65 style flywheel assembly, which uses a splined sprocket shaft and Timken sprocket shaft bearing Although this necessitates the use of a 1954-64 style inner tin primary cover and primary chain sprocket, the increased flywheel stability strength and power handling capacity are worth a slight departure from stock Flathead Power rocker arm cover "tins" are another modern improvement S&S has improved the design of the oil lines for better reliability and easier assembly and maintenance KN series engines come completely assembled and ready to run with a present SS Super Stock electronic ignition system and Super E carburetor KN Series engines come with a 12 month warranty S&S engines are shipped without oil Not legal for sale or use in California on any pollution controlled motor vehicles