Sometimes a vehicle design is so good at what it does that it sticks around seemingly forever. The Volkswagen Beetle, the Mercedes-Benz Gelandewagen, and the Harley-Davidson XR-750. The now iconic motorcycle was introduced for 1970, to meet changes to American Motorcyclist Association Grand National Championship rules. After a slight change to the engine for 1972, the bike has remained largely unchanged. It became one of the most successful bikes in racing history, winning 29 of the next 37 championships, and being used by famous stunt rider Evil Knievel from 1970 to 1976. It's still used by the Harley-Davidson flat-track racing team.

But now, after 46 years, there is an all-new replacement: the XG750R. The new bike is based on the 750 street, rather than the Sportster the old model was based on. It's powered by a liquid cooled HD Revolution X V-twin engine and will debut in competition this weekend at the AMA Pro Flat Track in Springfield Illinois. The race engine and frame were developed by Vance & Hines and the bikes will be raced by the Screamin' Eagle factory race team in their introductory season. At this point, the bike is for race use only, and will not be for sale for the street.