When the FIM announced new regulations for the 1968 Grand Prix motorcycle racing season that limited the 500 cc engines to four cylinders, this gave an advantage to teams using two-stroke machinery.

In November 1977 Honda announced it would be returning to motorcycle Grand Prix racing using four-stroke technology.

[3] Since a conventional four-stroke, four-cylinder engine could not produce the same power as its two-stroke rivals, Honda increased its valve area to be competitive.

The oval cylinders allowed room for 32 valves and eight spark plugs, the same as that of an eight-cylinder engine while staying within the four-cylinder rules limit.

[6] Honda overcame significant manufacturing problems to develop its oval cylinder technology and by late-1979 the bike made its debut at the British Grand Prix ridden by Mick Grant and Takazumi Katayama.