Impact of Removing VFR Air Pumps

by Bruce Wilson

vfr

This interesting article was written by Bruce Wilson who has graciously allowed me to place it here. This was originally a post on the VFR List and was a response to the question "Will air pump and EVAP canister removal adversely affect the way the bike runs?"

If done properly and completely, removing the air pumps and canister will have *no* negative effect on performance. The air pumps draw air from the airbox through vacuum actuated pumps that get their vacuum off the intake manifolds. There may be certain rpm's conditions where the airpumps sucking air from the air box negatively "competes" with the air for the carbs and the pressurization that is all important in a CV carb. But it is probably so minor that you would need more than a VFR trained butt sitting on the seat to notice it.

If you plug the vacuum ports on the intake side, plug the air pickup points on the airbox side, seal off the airpump vacuum tap and lines running to the exhaust, then air pump disabling and removal will not hurt performance. The charcoal canister purpose is to take gas vapors and collect and "recycle" them by venting some to the atmosphere and re-burning the rest. This can create an overly rich condition if the canister becomes saturated with gasoline from a tank overfill. Properly removing this plumbing and capping off what is not needed and venting to the atmosphere is how 99% of all motorcycles do it anyway. (Editor's Note: The pumps, lines, etc.. probably weight about 3-4 lbs.)

If you block off and remove your airpumps and/or etc. and your bike runs worse, then you did something wrong. Canadian and most European markets don't even get the airpumps let alone the canisters. Don't know about Down Under.

Bruce in Tucson
'96 VFR750F


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