The Harley-Davidson Motor Company was founded in the year 1903 in Milwaukee, Wisconsin. With the introduction of its early motorcycles, Harley-Davidson quickly gained a loyal fan base. Motorcyclists fell in love with the low-sitting bike that was ideal for cruising.

People also seemed to really like the big powerful motors that were placed into Harley-Davidson's bikes. In fact, the company broke records in the 1930s and 1940s with their knucklehead engines with a displacement of 80 cubic inches (1340cc). During the war, the company scaled back on their production costs, which resulted in smaller motors being placed into their bikes.

However, in 1982, the 1340cc engine made a return. The engine made a comeback in the newly introduced Harley-Davidson Softail. The original Softails were equipped with V-twin engines and hidden rear shock absorbers.

In 1990, Harley-Davidson introduced the Fat Boy as part of its Softail line of bikes. The name stirred up controversy because many people believed it was derived by combining the names of the two bombs that were dropped on Nagasaki and Hiroshima. The original Fat Boy returned Harley-Davidson to the top of the sales chart for heavyweight motorcycles.

Over the years, the Harley-Davidson Fat Boy has stayed true to its name. For instance, the 2005 Screamin' Eagle Fat Boy comes equipped with a 1690cc twin cam engine. This is the largest engine that Harley-Davidson has offered to the general public thus far.