1906 Harley-Davidson Single

Harley-Davidson production in 1905 and 1906 were all single-cylinder models with 26.84 cubic inch (440 cc) engines but as early as February of 1907 a prototype model with a 45-degree V-Twin engine was displayed at the Chicago Automobile Show.
Although shown and advertised, very few dual cylinder V-Twin models were built between 1907 and 1910.
Production jumped from 450 motorcycles in 1908 to 1,149 machines in 1909.