Layout: An oval housing with a triangular rotor circulating around an offset, lobed shaft to form inlet, exhaust and ignition compartments. Benefits: Compact, high power-toweight-ratio, simple design.
At the age of 17, German inventor Dr Felix Wankel came up with the principles for an engine that would change the world. Unlike a conventional piston motor, which loses significant amounts of energy as it changes reciprocating energy into a rotational movement, the engine he would patent just five years later would see efficiency never known before.
Working in partnership with NSU in the 1950s, Wankel built a series of prototypes and the rotary motor began reaching the production lines in the early 60s; first being used in NSU’s Spider car in 1964.
The bike world was keen to capitalise on this innovative configuration and East German manufacturer MZ was the first to toy with a 175cc air-cooled version of Wankel’s design, doubling the performance output of the equalcapacity, conventional piston motor it had replaced. Impressive as it was, reliability problems compromised the rotary engine’s success.
Over time, more and more brands took to Wankel’s design, with Yamaha the first of the Japanese to showcase a rotary-engine machine in 1972 – the RZ201 – which unfortunately never made it into production. Suzuki, however, saw huge popularity with the RE5, which it launched in ’73.
Its price held it back and by ’76 Suzuki called time on the model that sold over 6000 units. Hercules was next to pick up the rotary in 1974 – in tandem with DKW – before selling off all its tooling to Norton in ’77. By this point, Norton had been developing its rotaries for seven years, with the Interpol II – a model built exclusively for the police – eventually making the production line in 1984.
In ’87, 100 examples of the rotary Norton Classic were released, with 85bhp on tap. The Commander came next, but that too failed to sell in large volumes.
Everything changed in 1990 when the Norton F1 racer cleaned up in the 1989 British F1 championship.
The future for rotaries looked bright once more, but product sales failed to come and the rotary was eventually floored with Norton’s demise.