If there is one motorcycle that could be considered the archetype of lightweight bikes, it would have to be the DKW RT 125. Even if you’ve never seen one before, you’ve most likely seen traces of its iconic design in other bikes. Since its inception in the 1930s, the DKW RT 125 has gone on to be one of the most copied motorcycles of all times and there are some very specific reasons for this we’ll discuss below.
Origins of the DKW RT 125
The name “DKW” comes from a two-stroke engine built in 1919 by the Danish engineer Jørgen Skafte Rasmussen, in Saxony, Gemrany. It was this small engine, which Rasmussen called Das Kliene Wunder (the little marvel) that gave DWK its start in the motorcycle industry.
By the 1930s, DKW was the largest manufacture of motorcycles in the world. The RT 125, designed for DKW by Hermann Weber, came along in 1939. It was considered a masterpiece of design and functionality based on its streamlined looks and efficient engine.
The engine featured flat-topped pistons rather than deflector pistons made possible by DKW’s pioneering development of the Schnurle two-stroke scavenging process. This efficient means of collecting the air-fuel mixture was further aided by DKW’s unique arrangement of transfer ports.
Immediately after the release of this motorcycle, DWK’s competitors, such as Adler and TWN, switched to flat-topped pistons and attempted to design similar transfer port arrangements. However, it was WWII that allowed the RT 125 to be widely copied throughout the world.
World War II Reparations and RT 125 Copies
As WWII drew to a close in 1945, DKW’s factories had either been damaged or occupied by the Red Army. The Soviets took DKW plans, tools, and even personnel back to Moscow where copies of the RT 125 were soon produced. The Soviet version of the RT 125 was first released in 1946 as the Moskva M1A and later as the K-125.
In addition to the Soviets, the US and the UK also began to produce copies of the RT 125. As part of Germany’s war reparations, DKW plans were handed over to Harley-Davison in the US and BSA in the UK.
Harley-Davidson took the plans for the RT 125 and came out with the Model 125 in 1948. An updated model called the Hummer was added to Harley’s lineup in 1955, and subsequently all Harley single-cylinder two-strokes built between 1948 and 1966 have come to be known as Hummers. The last RT 125-based motorcycle built by Harley was The Bobcat produced for one year in 1966.
BSA adopted the RT 125 design for their BSA Bantam. The Bantam went into production in 1948 and would go through several iterations until 1971. Although the frame changed drastically over the years, the engine remained very similar to the original RT 125 model.
SHL, a Polish brand of motorcycles produced from 1938 until 1970, brought out their version of the RT 125 in 1947. The SHL 125 used parts and frames from the manufactures pre-war motorcycles, but it included a copy of the RT 125 engine produced by PZL Psie Pole in Wroclaw.
Some of the earliest Japanese motorcycles borrowed heavily from the DKW RT 125, especially the Yamaha YA-1. Just like all the bikes mentioned so far, this model was driven by a 125 cc two-stroke single-cylinder engine.
The YA-1, first produced in 1955, is generally similar in appearance to the RT 125, but Yamaha wasn’t looking to make an exact copy. They brought their own engineering expertise to the development of the YA-1, which would result in a long line of successful two-stroke engines for many years to come.
The list of motorcycles inspired by the DKW RT 125 goes on and on. If you’re interested in discovering more DKW lookalikes, we recommend checking out the bikes below for starters.
- Czech 1949 Jawa 125
- 1955 Kawasaki (Meihatsu) 125
- Italian 1950 MiVal 125T
- German 1941 NSU 125 ZBD
- Hungarian Csepel 125