Unknown part

[Kevin]

So I was checking my vent tube going all the way back to the end of the tube and this was online which is im guessing a ball valve of sorts.. problem is I didn't pay attention to the direction it was instead because it seems I can only blow air through one direction. Any help would be greatly appreciated.

[roadiemort]

[Kevin]

Yes thats the part but my question is which end is up, theres no arrow showing direction of flow. If I hold it vertical in one direction I can blow air through it but if I flip it over and try I can't blow through it. I'm assuming it goes in the direction that I can blow air through it in the downward position?

[scotto]

Looks like the rollover valve I removed and spliced the two hoses with a metal, plastic or similar tube. I tossed it in the trash. Don't recall which end is "UP" if reinstalling.

[Chooch]

This is how mine was when I removed it. I wrote the orientation on it when I removed it in case I would ever need to reinstall it later.

[Shores]

It should let air into the tank and prevent fuel from coming out of the tank so do some experimentation to see how it would be oriented.

[roadiemort]

https://www.yamahasportsplaza.com/oe...0c70/fuel-tank

[Duke]

It's a double acting check valve, that lets small volume of air move in both directions when setting upright. They seem to easily malfunction, which causes a lot of fuel problems. Like scotto and many members on this form, I removed mine and replaced with a connector.

[MikeyC]

I've done the same, replace with piece of tube

[Kevin]

Yeah I'm wondering if that was the culprit for my gas tank building pressure and when I tried to remove the gas cap it was like mt saint belen... it just erupted and went everywhere.

[scotto]

Keep us posted.

[brianmac]

spot on Duke, it connects to tankvent, and allows fumes out , but also prevents liquid out in an event. IN the heat of florida, with black bike, if you bend down and look at bugs eye view, you can see the distortion of objects due to the ginormous amount of gasoline fumes spewing out from below the motor scooter. if that bad boy gets broke, or bugs move in, that would increase fuel tank pressure, and contribute to carb puke. er , shit, havent checked that on my trike yet.

[Kevin]

So its a year later and the problem seems to be back, was getting ready for the season and getting ready to change fluids so I let it run about 5 min and when I got it on lift I smelt and saw gas... sure enough coming out of gas cap again. So I took the breather hose off the little neck at the top of the tank and I can't seem to get air into or out of that little spout. So if thats the only vent for this tank, what the heck do I do now??

[Lug Nut]

Bypass it and never worry about it again

[SbTx_Rider]

If you bypassed the check valve, check for kinks in the hose, dirt/road grime or if something crawled into the tube and plugged it up

[Kevin]

I'm sorry but by pass what, the check valve? Its not hooked up thats my point, theres nothing hooked up to it. I just put like a 10 inch piece of clear hose on it and tried pushing air through the little spout vent on top of the tank and it doesn't seem to want to pass any air at all so it almost seems as if the that little vent tube itself is clogged. So if thats the case and thats the only vent what do I do if the tank is not venting at all?

[Chooch]

I have the same issue. If I leave my bike parked in the sun it builds up pressure in the tank. It will start but runs out of fuel. Remove the gas cap to relieve the pressure and the fuel starts flowing and bike runs fine. I removed the rollover valve long ago. I can blow compressed air through the vent hose and air will come out of the fill hole. It acts as though the vent tube has a check ball inside that will allow air into the tank but won’t allow air to escape out of the tank. I’m now in the habit of opening the cap before starting the bike after it has been parked.

[SbTx_Rider]

Has the tank been repainted? If so, paint maybe blocking the tube.
Have you tried to push a piece of wire into the tube?

If you have done all of that, there is thread about venting the gas cap

[Kevin]

It was already custom wrapped when I got it so its not original. Yes I've tried a wire and I can only get it so far then it stops almost like its hitting the inner part of the tank or something. I was trying to avoid the gas cap because I was worried if it builds pressure again I'm afraid it'll come out the cap plus I've read on here that it leaks and stinks up the garage. You see why I'm at aoss here.

[SbTx_Rider]

You should be able to push a wire into the tank. That tube vents/equalizes the pressure in your tank.
I would get about a 1 foot piece of stiff wire and run it into the tank. It is either this or vent the gas cap.

[brianmac]

mud daubers are an annual thing.

[Flashback]

I remember back in the dark ages Doc Shadow posted some info on how to drill the small tube on the tank. I believe it makes a 90 degree turn on the inside of the tank and may also have a check ball in it. It's been a long time and I don't remember..