The Knucklehead that Changed the History of Japan


In 1936, Harley-Davidson began producing motorcycles powered by their new “Knucklehead” engine.  The Knucklehead was a major leap forward in engine design, going from the older side valve arrangement to one in which the valves were located over the piston.  The basic overhead valve layout is still used today in all current Harley-Davidson engines.  The photo above shows one of the first Knuckleheads to be imported into Japan and although it may not have been clear when the photo was taken, these new machines were the catalyst that started the Japanese motorcycle industry.

Back in 1930, Harley-Davidson was suffering through the Great Depression.  Desperate to keep revenue coming in the door, Harley-Davidson made a deal to license a motorcycle factory in Japan.  After five years of hard work, the factory finally started producing complete motorcycles.  These machines were based on the V-series side valve engines, so when the Knucklehead was introduced, Harley-Davidson insisted that the Japanese pay to license this new engine as well.

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