Which Harley-Davidson engine was introduced in 1909 as the company’s first V-twin?

Harley-Davidson introduced its first V-twin engine, an F-head design, in 1909.

The F-head arrangement placed the intake valve in the cylinder head while the exhaust valve remained beside the cylinder. This configuration was an intermediate step between early atmospheric-valve engines and the fully overhead-valve designs that appeared later in Harley-Davidson history.

The 1909 V-twin had a 45-degree cylinder angle, a layout that became strongly associated with Harley-Davidson. The company briefly returned to a simpler V-twin configuration after the first F-head’s production, and a more developed version appeared in subsequent years.

The F-head should not be confused with the later Knucklehead, Panhead, or Shovelhead engines. Those names refer to distinct overhead-valve generations introduced decades afterward, each recognized by the visual shape of its rocker covers.