Jump to content

Gas tank venting?


Recommended Posts

So when I got my bike I removed all the emmisions stuff. I installed a tank vent cap similar to this http://cgi.ebay.com/ebaymotors/MX-ATV-GAS-CAP-VENTS-NEW_W0QQcmdZViewItemQQhashZitem23060f4182QQitemZ150425518466QQptZMotorcyclesQ5fPartsQ5fAccessories

This lets air in but no gas out when you crash. Well it worked so well yesterday while riding I looked down and my radiator shrouds were all sticking out and out of place. Hmmm, I didn't crash. I stopped to check it out. Both sided bulged out. I opened the gas cap and LOTS of air came out and the tank slowly went back into shape. From then on every now and then I would losen the cap to let air out to keep the tank from expanding.

This hasn't happened to me before and it was only 70* yesterday. I figure it's only gonna get worse with the summer heat. Maybe the cap isn't working correctly anymore, but it doesn't seem like a part this is pron to fail. Thinking to just go back to the old method of a breather hose without a cap.

Anyone else have this happen before?

What's everyone doing to vent the tank?

Thanks, Mike

Link to comment
Share on other sites

those one way vent doodads done always cause problems but they often are the cause of exactly what your sympoms are- presure builds in the tank and either blows the hose off- or expands. If you ride in rough conditions- you will notice this while~ SM riders won't. Once this happens- it is an indicator to run just the vent tube.

Link to comment
Share on other sites

I had my TE out on one of the only sunny days last year and the one-way valve let so much pressure build up inside the tank that it distorted permanently. The tank became really hard to remove and the plastics didn't fit it properly afterwards.

I've removed the valve (which when tested works fine) as I can cope with losing a little fuel when I faceplant! Gravity normally holds the valve open so that it can breathe both ways, but a sudden buildup of pressure (say if the fuel is shaken violently on the trail) may be enough to shut the valve, I guess.

BTW, don't put the tank breather pipe down the steering tube. If fuel escapes down there it can get through the steering lock slot in the stem and wash the grease out of your lower steering bearing. And we all know what a PITA it is to fit a new bearing. As long as it won't puke fuel on your front tyre and is high enough to clear water crossings you're good to go.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

×
×
  • Create New...