BMW commissioned designer Hans Muth to oversee the R90S, which became the flagship of the boxer engined "/6" range.

Sporting distinctive two-tone paintwork, a bikini fairing and a new tail, the R90S was intended to shrug off the enduring image of BMW bikes as staid and utilitarian.

The R90S' type 247 "airhead" engine was a pushrod OHV, two valve per cylinder, air-cooled flat-twin "boxer" unit.

The engine was based closely on the R75/5, sharing the same stroke, but with a larger bore, to give a capacity of 898cc.

Feedback from unimpressed customers prompted BMW to return to hand painted pinstripes.

The R90S was succeeded in 1977 by the R100S, which retained the bikini fairing with altered paintwork, and whose engine capacity was increased to 1,000 cc.

Two R90S bikes placed first and second at the very first AMA Superbike race at Daytona International Speedway in 1976.

[6] British rider Reg Pridmore rode an R90S to win the 1977 AMA Superbike Championship.