Harley-Davidson FL

Harley-Davidson FL is the model designation that Harley-Davidson has used since 1941 for its large Big Twin motorcycles. The F stood for the new 74 cubic inch (1,210 cc) version of the overhead valve Knucklehead engine, introduced in 1936 as the 61 cubic inch Model E, and the added L meant higher compression. When the low compression version and the smaller EL were dropped in the early 1950s, FL became the basic Big Twin designation for decades. Further letters mark options, such as FLS for sidecar use, FLE for police and escort work, FLF for the traditional foot clutch and hand shift, and FLH for a more highly tuned engine. The line passed through the Hydra-Glide of 1950, the Duo-Glide with its swingarm frame in 1958 and the Electra Glide from 1965, and later grew to include the FLT Tour Glide, the Road King and the Heritage Softail models. Today the FL prefix signals the traditional 16-inch front wheel and large fenders, as opposed to the sportier FX models.