The original Sportster engine was the Ironhead engine, which was replaced with the Evolution engine in 1986.
Sportster motorcycles are powered by a four-stroke, 45° V-twin engine in which both connecting rods, of the 'fork and blade' or 'knife & fork' design, share a common crank pin. WL 739 cc engine Harley-Davidson 45° V-twin, Sportster Evolution engine It was the first motorcycle under the Sportster nameplate to receive a new engine since 1986, and the first Sportster to have an engine not derived from the Model K. An all-new model, called the Sportster S and equipped with the Revolution Max engine, was introduced in 2021. The original Sportster line was discontinued in Europe in 2020 because the engine failed to meet the stricter Euro 5 emissions standards. The first Sportster in 1957 had many of the same details of the KH including the frame, fenders, large gas tank and front suspension. These models K, KK, KH, and KHK of 1952 to 1956 had a sidevalve ('flat head') engine, whereas the later XL Sportster models use an overhead valve engine. In 1952, the predecessors to the Sportster, the Model K Sport and Sport Solo motorcycles, were introduced. Sportster models are designated in Harley-Davidson's product code by beginning with 'XL'. The Harley-Davidson Sportster is a line of motorcycles produced continuously since 1957 by Harley-Davidson.
