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Harley-Davidson Lightweights | History

Harley-Davidson Archives
Bill Jackson
12/26/2010

Click the images below for bigger versions:
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Post WW2 History

In the years following World War II, Harley-Davidson recognized the demand that lay ahead for economical and efficient motorcycles. In late 1947, production of civilian Big Twins had already swung back into gear, but most surprising for the 1948 model year was the new model S motorcycle.

The 125 model S motorcycle arrived at dealerships with an MSRP of $325, and if the customer could swing the extra $7.50, their new ride came with chrome rims. The single cylinder engine produced about three brake horsepower (bhp), which got the 200 lb. motorcycle up to about 55 mph.

The lightweights that followed over the coming years were important for another reason: They were a response to competitors, mainly European, that were taking advantage of the demand. In 1954, the 125 model S motorcycle was dubbed the Hummer. Following the development of the Hydra Glide front fork in 1949, the 125 model received telescopic front forks and was renamed the Tele Glide. Later incarnations in the 1950s saw an increase to 165 ccs, and sales were excellent.

The name of the Harley-Davidson lightweight was changed in 1960 to the model BT, or Super 10 motorcycle. With the displacement remaining at 165 ccs, the power was increased to nine bhp, but a five bhp version was offered in the U.S., where there were restrictions on the power available to a motorcycle ridden by young people. Sales must have been brisk, because in 1962, a line of lightweights was available, including the Scat, Pacer and Ranger models.

The Scat was dropped in 1963, the same year that Harley-Davidson lightweights were being produced out of the then newly acquired Aermacchi factory, in Varese, Italy. The 1963 Pacer and Scat models even included rear suspensions, which placed the springs beneath the engine, a kind of early version of the Softail model frame!

Harley-Davidson closed out its line of lightweights with the 1966 Bobcat motorcycle, a 175 cc model that also incorporated fiberglass components from the then newly acquired factory in Tomahawk, Wisconsin.

Ultimate MotorCycling would like to thank Harley-Davidson Motor Company Archives for the Photographs.


Comments

Introduced in 1939 by DWK the model RT125 went on to become the most widely copied motorcycle in the world after World War II. It's original factory was in the Eastern Zone of Germany and was produced there as a DKW. The DKW company resumed production in West Germany and call the model the RT125W to distinguish it from the East German model.

In England BSA produced the RT125, in Moscow it was made as the Minsk M1a, in the USA Harley-Davidson copied it as the Model 125, and in Japan it became the first Yamaha the YA-1 Red Dragon. There were also copies made in Poland and China.

The RT125 was the most popular dispatch rider motorcycle and achieved over 100 miles per gallon on highways. It was far better then the much heavier RT350 due to the poor quality of roads.

As part of the treaty to end the war all German motorcycle plans were ceded to the allows and their patents were voided. The RT125 has been the result of the research by Charles Day, who developed the Day two cycle engine it used. This design was improved greatly by Adolf Schnurle from Deutz who developed a superior flow pattern for the Day engine called Schnurle Reverse Flow. This dramatically improved fuel charging ability and removed the necessity for using a high domed piston. DKW obtained the exclusive license to use the reverse flow design and owned it's patent.

In the 1950s Walter Kaden of MZ (the later name of the East German DKW) improved the Schnurle dsign further by adding more ports which made the original DKW designs very successful in racing when coupled with the expansion chamber.

DKW also invented the Front Drive automobile, and is today a part of Volkswagen. Today's MZ RT125 is the current evolution of the motorcycle that Harley-Davidson copied from DKW.

Harley-Davidson started with a single-cylinder lightweight in 1903. It would be several years before they would begin manufacturing larger models. Eventually, the early models were dropped.