The Harley-Davidson Twin Cam engines are motorcycle engines made by Harley-Davidson since 1998. Although these engines differed significantly from the Evolution engine, which in turn was derived from the series of single camshaft, overhead valve motors that were first released in 1936, they share a number of characteristics with nearly all previous Harley-Davidson engines. Both engines have two cylinders in a V-twin configuration at 45°, are air-cooled, and activate valves with push-rods. The crankshafts have a single pin with a knife and fork arrangement for the connecting rods. These are sandwiched between a pair of flywheels.
The Twin Cam 88 was released for the 1999 model year in September 1998. The Twin Cam 96 was released for the 2007 model year.
The Evolution engine (popularly known as Evo) is an air-cooled, 45-degree, V-twin engine manufactured from 1984 by Harley-Davidson for the company's motorcycles. It was made in the 1,340 cc (82 cu in) displacement for Harley Davidson Big V-twins bikes, replacing the Shovelhead engine, giving way to most of the product line utilizing the new TC88 (Twin Cam 88 cu in), until 2000 when the last EVO was placed in a production factory custom (FXR4). In 2001, it was completely replaced by the Harley-Davidson Twin Cam 88. It was made in the 1,100 cc (67 cu in) displacement and is still made in the 883 cc (53.9 cu in) and 1,200 cc (73 cu in) (replacing the 1,100 in 1988) displacements since 1986 for the Harley-Davidson Sportster, where it replaced the ironhead Sportster engine.
Most analysts consider the Evolution to be the engine that saved the reorganized Harley-Davidson company from certain bankruptcy. Harley-Davidson's official name for the engine was likely related to the company's attempt to reform its image following the 1981 management buyout from previous owner American Machine and Foundry (AMF).
Harley-Davidson Inc (NYSE: HOG, formerly HDI), often abbreviated H-D or Harley, is an American motorcycle manufacturer. Founded in Milwaukee, Wisconsin, during the first decade of the 20th century, it was one of two major American motorcycle manufacturers to survive the Great Depression. Harley-Davidson also survived a period of poor quality control and competition from Japanese manufacturers.
Since 1977, the only motorcycles sold to the public under the Harley-Davidson brand have been heavyweight motorcycles, with engine displacements greater than 700 cc, designed for cruising on highways. Harley-Davidson motorcycles, or "Harleys", are noted for the tradition of heavy customization that gave rise to the chopper style of motorcycle. Except for the modern VRSC model family, current Harley-Davidson motorcycles reflect the styles of classic Harley designs. Harley-Davidson's attempts to establish itself in the light motorcycle market have met little success and have largely been abandoned since the 1978 sale of its Italian Aermacchi subsidiary.