Harley Knucklehead Motor, 2022

Description

Aesthetics and Engineering: Pre-1970 Motorcycle Engines Series

Motorcycles entered the public zeitgeist in the early 20^th Century as basic, affordable transportation.  They were quickly adapted to the new sport of motorcycle racing, be it oval speedway/flat track/dirt track, tourist trophy on public streets, race tracks, trials, dirt bike and desert racing.  Motorcycle design was driven by the need to increase speed, keep weight low, maintain a narrow profile, and provide adequate suspension.

Between the two World Wars, the evolution of engine designs took on an aspect of engineering aesthetics as with rare exception motorcycle engines were fully visible.  In America, as the original marques declined to just Indian and Harley Davidson, and finally just Harley, the brutish 74 cubic inch vee-twin cylinder reigned supreme, first with finned flathead engines, followed by the “Knucklehead”, “Panhead”, and “Shovelhead” designs all related to the valve train. In Europe, an especially England, the big single cylinder “thumpers” followed by the side-by-side twins of a dozen manufacturers were highly popular.  These engines were elegantly shaped and stylishly black with polished aluminum and a highlight of chromium to offset interesting external engineering features.

The Harley “Knucklehead” so named because the cylinder head looked like knuckles on a fist was the first Harley overhead valve motor and replaced the previous flathead design in 1936 and continued in production until 1947.  It was immensely popular with “bikers” and this image represents a late-model motor.