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Join Date: Nov 2007
Location: Chandler, Arizona
If you here a hissing sound from around the gas cap, you have a problem. There should never be more or less than atmospheric pressure inside the tank. The CA evap system is prone to failure, and will allow pressure to build up in the tank. I took my cap apart, took everything out, then put it back together. I did not put anything in it. The tank must be vented somewhere. Remove the seat and see if you have two fittings at the rear of the tank or just one. Either way there should be a hose one it/them. If it has two, then you have the dreaded CA evap system. Get some rubber tubing that will fit the fittings on the tank, if you have two, put hoses on both of them, and run the hoses down through the holes in the frame, and down underneath the tank. Also check that rubber grommet. That is the tank vent. It leads to a passage that exits at the rear of the tank where the hoses go. If it is missing, it would probably leak gas onto the top of the tank when full.
But, I have had several dirt and dual sport bikes that had the vent right in the middle of the gas cap. Again, a vent alone should not cause a gas smell. It sounds more like a leak to me.
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