BMW R 90 S

The BMW R 90 S is a produced by the company BMW motorcycle with a two-cylinder four-stroke boxer engine with 898 cc displacement. It is the top model of the so-called "dash six " series.

The R 90 S and its smaller sister models R90 / 6, R75 / 6 and R 60/6 were produced from 1973 to 1976. The R 90 S was just under 200 km / h one of the fastest production motorcycles in the world. They sprang from the efforts of BMW, the stronger the competition motorcycles ( such as Norton 850, Moto Guzzi GT 850 L, Laverda 1000 Kawasaki Z1, Honda CB 750 Four, Harley -Davidson 1000) to stand up.

At the same time were also essentially undercar and outfit same at the BMW plant in Berlin Spandau, smaller displacement models R 75 /6 ( 37 kW) as the successor to the R 75 /5, and R 60 /6 ( 30 kW) as the successor to the R 60/5 built. A 500 - cc model as a direct successor to the 24 kW (32 hp) R 50/ 5, it no longer existed.

The gears were with the "dash six " series for the first time five-speed gearbox. The engines had a change of crankshaft: the balance is off, this engine series designed with heavy metal plugs, whereby the outer diameter of the crankshaft smaller and the installation and removal easier. The previous "dash five" motors have forged steel crankshaft weights on her; their crankshafts can be feed out only with great exercise through special recesses of the motor housing. With these measures, the motor housing were considerably more stable: it was realized in the experiment with 900 engines in the previous model, that the old housing was no longer wearing the higher forces larger cylinder.

To meet the over its predecessors enhanced driving performance as it can, the 900 and 750 models were given a disc brake system for the first time in the front wheel. A Bowden cable operated in the machines with disc brakes the master cylinder under the tank. Only the R 60/6 in series still had a duplex front drum brake. Hardly anyone but It left, but often ordered when purchasing an identical disc brake. Therefore today are original R 60 /6 with drum brake, a rarity. Many of the smaller models, the double disc brake of the R 90 S also received the same ordered: the subsequent conversion to two discs is very complicated, because the front fork dip tube on the " nonbraking " page has no preparation for receiving a brake caliper and thus replaced when converting to double glazing must be.

All models have a double-loop tubular frame and shaft drive to the rear wheel. Compared to the "dash - Five " series the wheelbase had been extended by 80 mm, which means increased load change reactions of the universals weakened somewhat and on the other hand allowed the installation of a larger starter battery.

The R 90 S ( the first production motorcycle in the world) a racy cockpit panel made ​​of fiberglass reinforced plastic and a rear rump. It was painted in Daytona Orange or in smoke silver as history painting ( a major cost factor for any necessary restoration).

In the fall of 1976, the R 90 S was replaced by the R 100 RS and the R 100 S, R 90/6 replaced by the R 100/ 7, and R 75/6 of the R 75/7. The result series is accordingly called "Dash Seven".

Specifications