02 WR426 tank vent quesiton

Hey Guys,

This past week I noticed that anytime my fuel tank heated up the vent would gurgle and fuel would leak out of it. The fuel level was about 3 inches below the cap, and the first time I noticed this the bike had been sitting for about 3 hours or so. It had been sitting in the sun and the tank felt warm to the touch. I have not taken the cap apart, and I don't know what to expect in there. Loosening the cap will release the built up pressure, but it quickly rebuilds. Any ideas on what causes this and how to fix it? Thanks,


This observation by you was real popular in 1999-2000.

The check valve prevents fuel from leaking out on a tip over, but does allow air to be drawn into the tank as the fuel level decreases.

Several guys found their tanks pressurized, JUST LIKE YOU, which would have a bizarre and disasterous effect on their jetting.

The tank presses up due to the ambient temp increasing and / or an aftermarket header pipe that is too close to your tank. I have ALWAYS seen this on gas cans.

To stop this, remove that stupid check valve & chuck it into the trash. Run your vent hose like all bikes before the EPA stepped into the pic or like my 06CRF.

BTW, there was at least one person a while back that made it a personal goal to prove these tanks DON'T pressurize. :excuseme:

Thanks Kevin, I thought that this would be my course of action. Just thought I would check with you guys.


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