BMW GS

The BMW GS series of dual purpose off-road/on-road BMW motorcycles have been produced from 1980, when the R80G/S was launched, to the present day. The GS refers to either Gelände/Straße (German: off-road/road) or Gelände Sport. GS motorcycles can be distinguished from other BMW models by their longer travel suspension, an upright riding position, and larger front wheels – typically 19 to 21 inch. In May 2009, the 500,000th GS was produced, an R1200GS model.

The GS has been available with a range of different engines, including single-cylinder, twin-cylinder water-cooled and twin-cylinder air- ("Airheads") and air/oil-cooled ("Oilheads" and "Hexheads").

The first shaft driven GS model was the R80G/S with a 797.5 cc air-cooled, flat-twin boxer engine. The BMW 247 engine, which was also fitted to many other bikes in the BMW range, is known as an airhead, because it relies on airflow across the cylinder heads and cylinder 'barrels' to provide most of the cooling for the engine. The most valued version was the R80G/S-PD "Paris-Dakar" model featuring a larger tank, which was launched in celebration of the R80G/S wins in the Paris Dakar Rally. In certain markets a 649.6 cc R65GS version was also available. These early machines used a combined rear suspension and drive swingarm called a Monolever.

In 1987, the G/S name was changed to GS with the S meaning "Sport" rather than "Straße" and the Monolever was replaced with the Paralever swingarm, which included a torque arm intended to lessen shaft effect and strengthen the swingarm-to-final drive connection. The new bikes were produced with engines of 797.5 cc (R80GS) or 980 cc (R100GS).

Production of the standard machines stopped in 1995 with the R100GS-PD (unofficially Paris Dakar), but special "Kalahari" and "Basic" editions were made available in 1996 and 1997, which ended airhead GS production.

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Wikipedia