Just as Kawasaki was about to green-light the world's first mass-produced across-the-frame four-cylinder motorcycle, Honda pulled the rug out from under them, unveiling the CB750-4 at the Tokyo Show in 1968. It lit the fuse for what was to become motorcycling's most explosive decade. In never before published interviews, with the men responsible for the bike code-named 'New York Steak, ' Dave Sheehan relates the story behind the Z1's development; the secret US testing programme in which a team including Imola-race winner Paul Smart rode pre-production bikes disguised as Hondas...