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. The original Sportster engine was the Ironhead engine, which was replaced with the Evolution engine in 1986. Sportster engines, the 45-cubic-inch R, D, G & W Models 1929 side-valve motors, and the 'Big Twin' side-valve motors, which were: the flathead 74.0 cu in (1,213 cc) Models V, VL etc. (1930–1936), Models U and UL (1937–1948), and the 80.0 cu in (1,311 cc) models VH and VLH (1935–1936), models UH and ULH (1937–1941), have four separate cams, sporting one lobe per cam. The cam followers used in Sportster engines, K models, big twin side-valve models, and the side-valve W model series, were a slightly shorter version of the followers used in the larger motors, but featured the same 0.731-inch (18.6 mm) diameter body and 0.855-inch (21.7 mm) diameter roller follower used since 1929. The company used similar cam followers for decades, with minor changes, from 1929 to the 1980s.
Select version for changelog:
.
Thanks.