The RT125 and the globalisation of motorcycle manufacture
º What links DKW, BSA, MZ, Harley-davidson and Yamaha? One single design – the DKW RT125.
DKW started as a producer of clip-on engines for bicycles in Germany in 1919 and by the 1930s were the biggest motorcycle manufacturer in the world. Then in 1938 Ewald Kluge, on a supercharged DKW 250, won the Lightweight TT and the 250 class of the European Championship, repeating the latter feat in ’39.
This success was achieved using complex liquid-cooled supercharged split-singles to achieve giddy power outputs and massive noise.
The breakthrough for road bike engines was the adoption of the Schnürle loop scavenging system in which angled transfer ports allowed the incoming fuel charge to chase the exhaust gas from the cylinder making for improved performance and economy.
The RT125, designed by Herman Weber, was introduced on the eve of the Second World War. Unfortunately this meant the key beneficiary was the German military. The RT125 was a crisp modern design that rendered other lightweights obsolete.
Following the German defeat in 1945 the designs for the RT125 were offered to BSA and Harley-davidson as part of war reparations. The BSA Bantam was introduced in 1948 and was made until 1971, becoming the biggest selling British bike of all time. Harley’s version was introduced as the Hummer in 1948, and continued until 1966. Meanwhile the Soviets dragged all the tooling to Russia and began production of the Moskva 125, which evolved into the Minsk.
The East Germans found new machine tools for the Zschopau factory and re-started production of their own version of the RT125 first as an IFA and then an MZ. Soviet bloc comradeship meant it was also made in Poland as a Sokol, a WFM and then a WSK. DKW relocated to Ingolstadt in West Germany and made RT125 based designs until the 1960s. At this point the German market had shrunk massively, so the factory switched to making Audi cars. Phew. But we’re not done yet. Post-war Japan was also struggling with mobility and, in the case of Yamaha, limited demand for pianos. So, they bought an RT125, copied the design and produced their own version from 1955. It was painted red and christened the Red Dragonfly. No RT125, no M1.