Exhaust Vacuu

2 replies to this topic
  • SkinSF

Posted March 26, 2002 - 08:19 AM


I just saw the article in MXA about Ferry's 426. WOW. Wish I had the talent to ride that bike wide open!

Does anyone know what the concept is behind the road racing exhaust vacuum / pressure system? When will DrD have one for sale.

How about the new rear brake master cylinder. When is that going to be for public consumption.

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  • Shawn_Mc

Posted March 26, 2002 - 11:14 AM


I couldnt figure that out. Still on my mind.

On Doug Henry's bike they had a restrictor in the pipe that was basically a washer in the end of the head pipe that would at low RPM restrictive then at a certain place it would open like a throttle valve in car and let the pipe flow wide open. I heard that it made so much low end power that Jimmy Button didnt like it. He was kind of a rev'r from what I read.

  • DaveJ

Posted March 26, 2002 - 02:04 PM


To the best of my knowledge, it uses vacuum generated from the exhaust to remove crankcase pressures, so that the piston moves down with less resistance.

Sometimes road race teams will install pumps or multiple vent lines regarding the same purpose.


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