Evolution® Engine Innovation Air-cooled and durable as hell, the 883cc Evolution® engine is yet another nod to the unwavering work ethic that drives advancements in motor technology at Harley-Davidson. Aluminum heads and cylinders lighten the load of the bike and improve air-cooling efficiency. Electronic fuel injection says goodbye to carburetors and boasts increased reliability and less routine maintenance. Bottom line: the rubber-mounted Evolution® engine runs hard and rides smooth for thousands of miles so you can just worry about taking in the freedom of the open road.