Construction is almost entirely the same between 883 cc and 1,200 cc versions the chief difference between the two is a smaller bore on the 883 cc (inherited from its earlier "ironhead" parent), along with slightly different heads. The Sportster Evolution engine has remained largely unchanged from 1986 to the present day, though changes to the transmission, final drive and motor mounts have necessitated changes to the Sportster Evolution case. This configuration is friendly to radical, high-output cams, making the Sportster Evolution a natural choice for the once Harley-Davidson owned line of Buell Motorcycle Company sportbikes from 1986 up to late 2009 (2010 model year). This allows each lifter and pushrod to deflect from the cam lobes perpendicular to the lobe plane. The cam lobes are thus all located one behind another, and pushrods are arrayed in pairs (front and rear) parallel to the cylinder axis as a result.
Unlike almost any other engine in production today, the Sportster Evolution uses one cam per engine overhead valve, resulting in four individual, single-lobe, gear-driven camshafts.
#Harley evo camshaft upgrade
The unit construction of the Harley-Davidson Sportster, which has essentially been unchanged since its inception as the side-valve 750cc "K" Model in 1952, was retained with the Evolution engine upgrade in 1986, resulting in a unique valve train configuration.
Crank output is purple cams are red pushrod/lifters are yellow rockers are blue valves are dark green, with seats shown in light green. The blocky rocker boxes (thus becoming nicknamed "block head" which never caught on), aluminum heads and cylinders (also referred to as "jugs") are the only part of the Evolution engine that can be said to be essential the Big Twin and Sportster incarnations of the Evolution are significantly different.Ībove, a color-coded approximate diagram of the Sportster Evolution valve train superimposed over an image of a Sportster Evolution. Air cooling efficiency is improved as aluminum is a superior thermal conductor to cast iron. īoth the heads and cylinders of the Evolution engine are made from aluminum to reduce weight compared to a cast iron design. 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). Most analysts consider the Evolution to be the engine that saved the reorganized Harley-Davidson company from certain bankruptcy. Also available in the Sportster model beginning in 1986, it was made in the 1,100 cc (67 cu in) displacement until 1988 and is still made in the 883 cc (53.9 cu in) and 1,200 cc (73 cu in) displacements for the Harley-Davidson Sportster, replacing the ironhead Sportster engine. In 1999, it was replaced by the Harley-Davidson Twin Cam 88 in the Touring and Dyna model and in 2000 in the Softail models. It was made in the 1,340 cc (82 cu in) displacement for Harley-Davidson Big V-twins bikes, replacing the Shovelhead engine until 2000 when the last EVO was placed in a production factory custom FXR4 (FXR2 and FXR3 were the first CVOs). 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. ( Learn how and when to remove this template message) ( December 2009) ( Learn how and when to remove this template message) Statements consisting only of original research should be removed. Please improve it by verifying the claims made and adding inline citations. This article possibly contains original research.
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