SteveA
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- Joined
- Dec 20, 2011
- Messages
- 3,349
In 1978 Peter Williams told me he used 10.5" head to bellmouth end! Which is what I was using at the time! Now a little more.Someone was having a little mid range stutter with his hot cam so I suggested he experiment by adding velo stacks to increase the intake track length. So he attached a pair of velos and "95%" of the stutter was gone to be replaced by a significant increase in power. Approx 10" from the head to the end of the carb or velo stack is what's considered to be ideal by myself, Ron Wood and Leo Goff (Peter Williams used 12"). You can't always achieve that with an aircleaner and stock oil tank but any increase in length is an improvement because the longer air column gains momentum and creates a ram effect. All the best racers who have tried it know its value. The owner of the bike in the photos is working on an aircleaner now and is incorperating the velo stacks into the aircleaner box. Longer stacks are also being ordered for more experimentation.
Special order velo stacks are available from Japan as shown below. But I don't know how to order them as the website is written in Japanese. Extending the manifolds or boots should have the same effect but its best to keep most of the weight closer to the head.