1926 Harley-Davidson 7/9 complete with Royal Tourist Sidecar Outfit. Max Power: 8.68hp The Infamous F Head In February 1907, a prototype model with a 45-degree V-Twin engine was displayed at the Chicago Automobile Show. Although shown and advertised, very few Vee-twin models were built between 1907 and 1910. By 1911, some 150 makes of motorcycle had already been built in the United States of America, although just a handful would survive the depression of the 1910s. However, the design focus on performance and low compression power production ensured the success of Harley-Davidson and by the 1920s, Harley-Davidson was the largest motorcycle manufacturer in the world with its motorcycles selling in over 67 countries.