DKW

During the late 1920s and 1930s, DKW was the world's largest motorcycle manufacturer In 1931, Ing Zoller started building split-singles and this concept made DKW the dominant racing motorcycle in the Lightweight and Junior classes between the wars. At the same time, the company also had some success with super-charged racing motorcycles.

The motorcycle branch of the company produced very famous models such as the RT 125 pre- and post-World War II, and after the war it still made 175, 250 and 350 models. As reparations after the war, the design drawings of the RT125 were given to Harley-Davidson in the US and BSA in the UK. 

The Harley-Davidson version was known as the Hummer, while BSA used them for the Bantam. IFA and later MZ models continued in production until the 1990s, when economics finally brought production of the two stroke to an end. Other manufacturers also copied the DKW design, officially or otherwise. This can be seen in the similarity of many small two-stroke motorcycles from the 1950s, including a product of Yamaha, Voskhod and Polish WSK.