The Harley Davidson EVO Crate Motor
The Harley Davidson EVO Crate Motor, widely known as the Evo, is a V-twin engine designed by Harley Davidson, primarily for its Big V-twin motorcycles. This engine, introduced in 1984, replaced the Shovelhead engine and continued production until 2000, when it was replaced by the Twin Cam 88. The Evo played a pivotal role in the brand's revival during a critical period.
Introduction to the EVO Crate Motor
The Harley Davidson EVO Crate Motor is a 45-degree air-cooled V-twin engine. Introduced in 1984, it was designed to replace the aging Shovelhead engine. Specifically manufactured for Harley’s Big V-twin bikes, it came with a 1340cc displacement. In 1999, the Twin Cam 88 engine replaced the Evo in Touring and Dyna models. The Evo was also adapted for the Sportster line, with displacements of 883cc and 1200cc, replacing the Ironhead Sportster engine.
Sportster Evolution
To reduce weight, Harley Davidson designed the EVO Crate Motor’s cylinder and head using aluminum, replacing the cast iron construction. Aluminum is a superior thermal conductor, which improved the engine's air-cooling efficiency. The aluminum components, such as the heads, cylinders, and rocker boxes, were the most notable updates in the Evolution engine. The Sportster version of the EVO featured a unique design, utilizing a single cam per engine with individual gear-driven camshafts arranged in pairs, a departure from previous engine configurations.
Other Harley Davidson Models
The Evolution engine was used in limited edition models like the CVO FXR4, FXR2, and FXR3 until 2000. Prior to that, it powered the FXR, Touring, Softail, and Dyna models for 15 years. While the top-end design of the final limited editions was significantly altered, the main engine case remained similar to the Shovelhead. The Big Twin configuration saw a shift in design, with the vertical plane of the cylinders placed perpendicular to the cam lobes, improving engine performance and aesthetics.
