Silverback

Steve’s Vincent was ten horses up on last year’s figure when he ran it on the Silverback dyno shortly before leaving for this year’s Bonneville event. Much of that power came about because of a major change in cam duration. Given the fact that this is a Vincent, Steve can’t just order a new camshaft from Crane or Andrews. Essentially he had to make his own camshafts, with individual cam lobes ordered from friends at Zipper’s performance. Now most people, even very talented people, would be intimidated by the idea of creating their own camshaft. First, you have to get the lobes indexed correctly so the timing is right, second you have to weld the lobes to the shaft without any warpage. And of course the lobes meant for Harleys come with pretty steep ramps, which is not a problem for the Harleys with their roller lifters. Before Steve could even use the cam profiles from Zipper’s he had to first locate a roller-follower set up designed for Vincents, from a company in Australia.

All of which goes to show just how tough it is to build a competitive race bike based on designs that are over 60 years old. Like any good racer, Steve is never satisfied. When I asked him what’s next, he said, “more RPM. We’re running to 8,000 now, next year I want to turn 9,000.” How do you make an old V-Twin turn 9,000 RPM? With a shorter stroke and bigger bore.

Stay tuned.

Look closely and you can see that this is a one-off, hand built camshaft. Underneath is the drawing for the roller cam follower.

A man in his element, Steve Hamel, surrounded by mills and lathes and exotic parts for old motorcycles.