1909 marked the appearance of Harley-Davidson's first v-twin, though it was not until the adoption of mechanically operated inlet valves in 1911 (replacing the 'atmospheric' type inherited from the single) that production really took off. Known by the sobriquet 'pocket valve', this inlet-over-exhaust engine - built in 61ci (1,000cc) and 74ci (1,200cc) capacities - would remain in production for the next 20 years. The Harley single's belt direct drive was continued at first on the twin but the need to make better use of the engine's power characteristics, particularly for sidecar pulling, prompted the introduction of a two-speed rear hub for 1914. By this time, chain drive and a proper clutch had been adopted. Later that same year, a conventional, three-speed, sliding-gear transmission with 'step starter' was introduced on the top-of-the-range version of the twin which, with full electrical equipment, was listed from now on as the Model J. Periodically revised and updated, the Model J gained a front brake, stronger fork and pumped lubrication by the time production ceased in 1929.

Dating from the final year of production, this authentic example of Harley's landmark original v-twin has been part of an important European collection for many years and is a very good riding Harley. The machine is an older, quality restoration and although it has a few bumps and scrapes it still presents very well.