By the end of 1966, the motorcycle division of Honda was doing pretty well. They had just captured their fifth straight motorcycle Grand Prix World Championship, and were selling more motorcycles than any other manufacturer in the world. Most of their success, both in racing as well as sales, was with smaller displacement motorcycles. Honda debuted their CB 450 dual overhead cam parallel twin motorcycle, their largest displacement bike to date, that year, and it was immediately a global success.
Despite these successes, they weren't resonating in America the way they were in other countries. Their market share was starting to erode. Yoshiro Harada, the lead engineer for the CB450, went to America to better learn what the market wanted. He noticed that Americans were buying larger displacement bikes. They needed a larger model.