Float Bowl Vent modification

Float Bowl Vent modification


This section has been kindly provided by Rory (aka Rozz). It gives a visual explanation of Ken’s Float Bowl Vent modification

For a technical explanation of why you should perform this modification on Ram Air equipped bikes (’93 onwards) please read Ken’s Explanation of the Float Bowl vent mod. But remember that to really benefit from the mod you will also have to rejet the carbs (mainly going to smaller main jets).
I have just performed Ken’s famous VentBowl Mod, and decided to make some pictures for those who want to know more.

All you need is:

  • 2 pipes (Outside diameter:19mm length:86mm and the other:10mm x 35mm)
  • some small screws (to blank off the two vacuum lines left over)
  • some tieraps (tighten/seal lines)
  • piece of plastic (to blank off remaining hole in housing…but you can use your own imagination on this..this plastic is what i had laying around)

I think the pictures speak for themselves… I have chosen to leave the vacuum lines and just seal them off because I`m still testing.

My bike has: Factory Pro carb kit. FP Ignition advancer +4 Scorpion bolt-on muffler with stock headers. BMC Race airfilter in stock airbox Settings (in the Netherlands @ sealevel) main jet : Stock 1 shim under (stock) needles FP emulsion tubes FP springs Fuel screws: Stock I am still testing, but bike runs much cleaner..i think i will have to go for smaller main jets…but first wanted to test this mod.



Start the modification by removing the airbox
Small pipe put in between floatbowl vent and airhousing Note pipe between the suction valves installed
How it looks when all is done Remember to blank off the other hole in the airfliter housing!!! (the pipe on the top right side)
Parts left over This is what you should end up with…note using the rubber line off one of the valves!

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