In 1965, Honda used an inline six cylinder motorcycle to contest the 250 cc motorcycle Grand Prix World Championship. It was built at the time as a viable solution to compete against similar displacement two stroke power plants.
As was covered in this article on the Honda RC 166, the small six-cylinder engine proved quite capable. Interestingly, the idea of an inline six cylinder motorcycle for production use did not quickly follow. Until Benelli decided to build the Sei.
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