There was one motorcycle that dominated American dirt track racing in the 1970's and 1980's. This bike was the XR 750 Harley Davidson motorcycle. This particular Harley Davidson motorcycle was built specifically for the American dirt track racing series and when introduced in 1970 it soon became a legend on the track. Over the years the XR Harley Davidson motorcycle changed little in appearance and design except for the switch in 1972 from the older iron-barrel cylinder head motor to the  newer aluminum engine. this is when the XR 750 Harley Davidson motorcycle really began to dominate the professional dirt track circuit. Harley factory rider Mark Brelsford won several National Championships with the updated XR 750.

The initial idea for the XR 750 came from Harley Davidson race team manager Dick O'Brien who combined a Harley Sportster engine with the chassis of the outdated Harley KR racer. The first results were less than spectacular as the bike was underpowered, unreliable and as a result unsuccessful. The leap forward came in 1972 when Harley switched to the Harley Sportster motor and the true potential of the XR 750 Harley Davidson motorcycle came out. This is also the bike Evil Knievel used for most of his stunt jumps.

harley davidson motorcycle, harley sportster