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demand more powerful machines, which led to the introduction of the company’s first V-twin. The engine size of the single had increased to 30 ci (494 cc) in 1909, but Bill Harley had greater ambitions and paired two singles onto a crankcase at a 45-degree angle to create a 49 ci (803 cc) twin the same year. In theory this should have doubled the power output but, unfortunately, the twin was no faster than the single and caused the drive belt to

slip so was dropped and redesigned for its 1911 reappearance. By this time, the inlet valves had been modified to be mechanically operated by pushrods, as opposed to the previously atmospheric system that relied on engine vacuum, and four-figure engine revs were possible. A tensioning device was also introduced to minimize any power loss through the drivetrain. This F-Head engine – named after the shape of the valve ports – proved

 ABOVE: Walter Davidson with his Harley-Davidson motorcycle, 1908.