The early 1970s were trying times at Harley-Davidson. The effects of AMF’s takeover in 1969 were trashing the company’s reputation and finances, and the flood of incoming Japanese standards provided reliable low-cost alternatives. To make matters worse, Harley’s grip on dirt track racing was in jeopardy after Brits had twisted the AMA’s arm for a single allowable displacement, no matter the valve configuration. With the backbone of Harley’s racing department threatened, it was a mad dash to regain AMA supremacy from Triumph and BSA, resulting in the all-conquering XR750 and a lesser-known pavement star called the XRTT.
With scant resources to operate on, Harley’s initial effort at an OHV 750 was based on the 900 ci Iron-Head Sportster, with the engine de-stroked dramatically to fall with the allowable displacement.…