Boasting “27 big improvements”, the Stream-Line design offered a multiple position seat, a relocated gearshift and redesigned handlebars. Despite the improvements, Harley-Davidson offered the bike for sale at the previous year’s pricing in an attempt to boost sluggish sales. The 74 cubic inch powerplant was introduced in 1921 and was called the Superpowered Twin. The 74 cubic inch powerplant was introduced in 1921 and was called the Superpowered Twin.
Although commonly known as a JD, the model may be more accurately named the D. The J indicated a complete electrically equipped machine, where the FD was equipped with a magneto for ignition. The JD included a six-volt generator, battery, contact breaker points and coil, tail light and oil warning light.
Specifications: 24 horsepower, 74 cubic inch, two-cylinder V-engine. Transmission: Three-speed chain drive. Cost new: $335.