A Boxer-Engine Motorcycle by Harley-Davidson?

Back in the early 1940s, the U.S. Army asked Harley-Davidson to design a next-generation military motorcycle. The company was already producing the WLA, based on its traditional 45-degree V-twin. But the Army wanted a bike with one feature the WLA didn’t have: shaft drive. For its target, Harley chose another well-developed military bike -- BMW’s R71, then in use by the German Army. Harley’s version, the XA, was a near duplicate, right down to the flat-twin engine.

The Army ordered a test batch of 1,000 XAs. At the same time, the military also asked Indian to make a 750cc shaft-drive twin, and it came up with a 90-degree V-twin design much like recent Moto Guzzis. The idea was to put both new machines through their paces, and award a lucrative military contract to the winner.

The XA prototypes ... had a few significant developments beyond the copied engine. Breaking with H-D tradition, the throttle was on the left end of the bars and the hand clutch on the right, as specified by the Army. A massive rear rack would carry a then-lightweight 40-pound radio. And, starting in 1943, the XA also sported the company’s first telescopic fork. Mechanically, the large cooling fins stuck straight out in the breeze, reportedly keeping the XA’s oil temperature 100 degrees cooler than a standard Harley 45. At 4,600 rpm, the side-valve engine put out a claimed 23 horsepower.

The Army dragged its feet on picking a winner between the Harley and the Indian, the H-D factory looked for other potential uses for the XA motor, including sidecar rigs, snowmobiles, and even powering a 1,000-pound mini version of the Jeep called the Peep. None of the projects worked out.

Eventually, the Army finished its testing, and decided that neither new bike would be built. Instead, they bought several thousand more Harley WLAs. Mostly, though, the U.S. military decided to hitch its hopes to a vehicle that could go through anything, didn’t tip over, and required very little training to operate -- the Jeep.

The XA motor, despite its workable design, fizzled. Thus ended the Harley XA project -- and the idea of a tactical military motorcycle.

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