In 1970 and 1971 Herbert Schek had won the ‘German Enduro championship above 500 cc’ with a self-modified BMW R75 slash 5. After that, this championship was dominated by Maico’s.
So Schek asked Von der Marwitz, director of BMW Motorcycles, to try to establish a class above 750 cc, in which BMW could become a leader. That worked out, and Schek wanted to build an 800 cc off-road engine himself. But Peres, an engineer from the BMW brand’s development department, disagreed. He thought that his department should build such an engine themself, and was given permission.
The start: the GS 800
For this motorcycle, he started with the engine and drivetrain off the BMW R65, on which he mounted the 90 mm cylinders of the BMW R90. Together with the stroke of the R65, it achieved a cylinder capacity of 782 cc. Several engine parts were cast from magnesium and there was also a lot of ‘shopping’ at other brands. The motorcycle got the tank, the telescopic fork, the front wheel with drum brake and the saddle from a Maico, while the 17 inch rear wheel came from a Honda Goldwing (!). The mufflers came from the American version of the Yamaha XT500.
The new mono shock spring
The frame had the lines of the usual BMW slash 6 series models, but was constructed of Chromium-molybdenum alloy and weighed only 7 kilos together with the swingarm. Peres wanted to use a mono shock spring, but there was no room for a centrally placed spring/damper element because the air filter housing was in the way. That’s why he built the spring on the cardan tunnel. As a result, the right wishbone was already strong enough to hang the wheel on one side. But this did not happen because there was no hub without a thru axle available at the time. The left wishbone was therefore not built very strong and only served to attach the thru axle.
While that was not Peres’ intent, the later BMW R80G/S Monolever system would emerge from this. At the beginning of 1978 the motorcycle was ready and Peres used it in the German championship. He came in second behind Rolf Witthöft with his Kawasaki. In 1979 it was already decided that the R80G/S would come on the market, so that the importance of good results with the GS 800 also counted from a marketing perspective.
That is why BMW deployed twó teams during the Six-Day race. Two gold medals were won by Rolf Witthöft and Fritz Witzel. And in 1980 Witthöft became the European champion.
Paris Dakar rally
In 1981 the enduro regulations were changed and the European ‘Championship Enduro’ started. The new regulations in this championship gave the more lightweight single-cylinders an high advantage, so BMW from then on concentrated on the African desert rallies.
We know now how that all ended; the famous BMW R80G/S ‘Paris Dakar’ was ‘born’ a few years later.
This beautiful poster of German and Europe enduro-champion Rolf Witthöft, riding his BMW R80 GS boxer at the Six Days event in 1980 is now available in the shop. ◁