HARLEY-DAVIDSON XR Models/Series Timeline, Specifications & Photos

Harley-Davidson was an American motorcycle manufacturer founded in 1903. They had the headquarters in Milwaukee, Wisconsin, United States, and were one of the two significant motorcycle manufacturers to go above ground with the Great Depression, along with Indian Motorcycles.

In 1970, the American manufacturer released the Harley-Davidson XR-750, a racing machine made especially for dirt track racing. In addition, the bike was also made in an XRTT version for road racing.

The bike was designed in response to an AMA Grand National Championship rule change that allowed other Japanese and British motorcycles to outperform the dominant Harley-Davidson KR race model.

The XRTT road racing version of the XR-750 was fitted with an aluminum oil tank, a fiberglass fuel tank, and a fiberglass fairing with extra heat shields to protect the rider when riding in a tuck position.

Like the dirt track version, the road racing machine packed a Ceriani front fork and Girling shock absorbers on the rear, two Mikuni carburetors, a tuned dual reverse cone exhaust system, and a Smiths tachometer.

Unlike the dirt racing machine, the road version featured a disc braking system on the rear wheel and a Fontana four-leading shoe drum brake comprising two twin leading drum units mounted side-by-side in two drums.

The Harley-Davidson XRTT-750 was driven by a 748cc air-cooled V-twin engine fed by two Mikuni carburetors, delivering an estimated output power between 70-100 hp.