The Harley-Davidson XR-750 is a racing motorcycle made by Harley-Davidson since 1970, primarily for dirt track racing, but also for road racing in the XRTT variant. The XR-750 was designed in response to a 1969 change in AMA Grand National Championship rules that leveled the playing field for makes other than Harley-Davidson, allowing Japanese and British motorcycles to outperform the previously dominant Harley-Davidson KR race bike. The XR-750 went on to win the most races in the history of American Motorcyclist Association (AMA) racing. The XR-750 is associated with the careers of racers Mark Brelsford, Cal Rayborn, and Jay Springsteen, and was the favorite motorcycle of stunt performer Evel Knievel. Knievel used the bike from December 1970 until his final jump in January 1977. An XR-750 was included in the 1998 The Art of the Motorcycle exhibition, and one of Knievel's bikes is in the Smithsonian's National Museum of American History America on the Move exhibit. (Source: Wikipedia.org, CC BY-SA)