Whatever the classic British bike that you ride or dream of, Velocette is likely to be a brand that resonates to you. Back in the early 80s, the Venom Thruxton was my dream bike, but eventually I ended up with a more classic Norton Commando that I kept 12 years, a choice that I never regretted. subsequently I bought my first Vincent, but 35 years later I still have a twinge for Velocette when I see one.
So when I read Stuart Hooper’s successful attempts to become the “World fastest British single”, it definitely raised my interest. In 4 years, Stuart collected world records both at Bonneville, Utah and Lake Gairdner, Australia, starting from 139.001 MPH in 2010 to 146.351 MPH in 2011, 171.600 MPH in 2013 and finally 183.370 MPH in March this year. Over 295 KPH on a single, that really made me even more curious to find how did he achieve this performance, as everyone guess, the bike could not be stock.
Hooper’s challenge started in 2008 when he bought a completely restored Velocette 350 Viper, which became the mule for his record bike. After stripping it to the bare minimum, all road equipment and the standard engine were stored and a race engine was built from scratch. Several bore and stroke configurations were tested, but the 93 x 102mm, resulting in a 700cc displacement, was assessed as the best trade-off between performance and reliability. With a compression ratio raised to 14:1 in order to run on methanol blended with nitro-methane, the engine is capable to rev safely 7,000rpm. The carburetor was replaced by a 1 ½” Grand Prix and an old BTH-TT magneto was selected to fire the engine. Interestingly the stock Velocette gearbox is matted to the new engine with a belt primary drive but as Hooper explained, “with a higher ratio in order to reduce the torque that the clutch and gears have to cope with”. In this configuration, Hooper best run was 146.351 MPH at Bonneville in 2011.
The natural aspirated engine likely could not do better, so the next step was the addition of a supercharger in 2012. In this configuration, Hooper achieved 171.600 MPH during the 2013 Bonneville Speed Week and his latest new record at 183.374 MPH this March 9, 2014 at the Speed Week on Lake Gairdner. I think all Classic bike enthusiasts can be proud and glad that Velocette became the world fastest British single, even if this mean that Brian Chapman’s Vincent Mighty Mouse had to lose his title in this battle: after all, records are meant to be broken. On the finish line Stuart Hooper commented “Now the question now is just how fast can a Velo go?”… I guess Stuart is already thinking to address this question very soon. The other burning question is: “Will someone challenge Hooper’s record on a Vincent Comet?” Bets are now open.
Philippe Guyony © 2014
The Velocette scrapbook:
Stuart and his crew have done an incredible job. I would like to think that a Comet could compete with the mighty Velo, but it is a daunting task. Stuart’s success in great part is due to his ability to focus keenly on the obstacles and using as much of the existing known speed formulae as possible to build his bike. Even with such a methodical approach it is often the “guesses” that can “make” or “break” you. In 2011 at Bonneville Stuart was trying to hit 150 MPH with the 700 naturally aspirated engine. While setting a record, he did not hit 150 MPH and he was quite determined to do so. After some additional dyno tuning and another set of runs the problem became clearer. He told me he was mixing fuel and jetting for the exact elevation at Bonneville. That would not work. He had to mix and jet for somewhere near double the altitude. Many times this only becomes clear on the flight home! That’s Bonneville!
Quite increasable that Stuart was able to use the original gearbox, the Mighty Mouse record was there to be beat.
Only with single minded perseverance can these extreme achievements be reached.