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Join Date: Nov 2007
Location: Chandler, Arizona
That is incorrect, but with some designs may be unavoidable. The vent should be big enough to INSTANTLY release any pressure or vacuum in the tank. I have such a vent on my CA model, I use the overflow fitting (the one that is not on non CA models) as a vent, and it is the same inside diameter as the inside of the vent hose, all the way into the tank. Maybe CA models are the ones to have, if it is not possible to properly vent the tank on non CA models. I would still remove that valve, and also remove the little rubber grommet at the back of the gas filler opening on a non CA model. That little grommet is apparently the passageway from the vent hose into the tank, and with todays alcohol gas, they tend to swell up and block the vent. If I couldn't get rid of the hissing (which is a symptom of insufficient venting) any other way, I would drill a hole in the cap, install a fitting in it, and connect a rubber vent hose directly to the cap, like it is done on dirt bikes. No hissing for me thank you. By the way, my Vulcans, a '93 and an '02, both CA models, are the ONLY bikes I have ever owned that did that. And they didn't do it for long.
I am a motorcyclist, NOT a biker.
1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike