emu
Ariel Motorcycles

Ariel 1931 Model 4F 500cc Square Four

Ariel-1931-Model-4F-Square-Four-500cc-NZM-1.jpg
In 1931 Ariel released the first production model of Edward Turner's square four, which had caused quite a sensation when seen by the public at the previous year's London Olympia show.

Courtesy New Zealand Classic Motorcycles