That infamous gas cap O-ring-- Where's it go?

[bobhamlin]

The O-ring came in today and, to me, it's not obvious where it goes.

At the risk of doofus-hood, can somebody help a brother?

The microfiche sticks it out to the side of the gas cap with no directing lines. It looks like the small side is up.

Does it go on the little cone-shaped object on the top of the gas cap?

Or on one of the bottom openings on the tank?

Maybe this is why so many bikes are missing them.

[cactusjack]

Is this the o-ring that goes around the locking mechanism, up near the cap?

[bobhamlin]

Originally Posted by cactusjack

Is this the o-ring that goes around the locking mechanism, up near the cap?

Don't know. Up until I actually had to do something with it, it's just been "the O-ring." I ordered the only gas-cap-related O-ring-looking thing I saw in the microfiche that I didn't seem to have.

[cactusjack]

How big is it? Something like 1-1/2" diameter?

[bobhamlin]

Originally Posted by cactusjack

How big is it? Something like 1-1/2" diameter?

The largest diameter is 1/2". It steps down to 3/8". (I'm sure they are probably metric equivalents, but my handy rule only provides inches.)

I'm beginning to think this O-ring goes under the hinge, allowing the cone shaped orifice on the gas cap to plunge into it. (Hmm-- Maybe we want to move this to the off-color section)

[cactusjack]

Originally Posted by bobhamlin

The largest diameter is 1/2". It steps down to 3/8". (I'm sure they are probably metric equivalents, but my handy rule only provides inches.)

I'm beginning to think this O-ring goes under the hinge, allowing the cone shaped orifice on the gas cap to plunge into it. (Hmm-- Maybe we want to move this to the off-color section)

I just went out and popped my gas cap. If you are sitting on the bike and open the cap, there is a small hole to the right of the cap hinge, in the fixed side of the hinge, which matches up with the vent tube in the cap assembly. (not to be confused with the small hole in the tank flange, which is a drain hole) I see a small o-ring there. Maybe that's it.

[rewindgy]

Okalie dokalie!
A) remove the complete gas cap assembly ( there are two screws with Philips heads) DO NOT LOSE THE TWO SMALL O-RINGS BETWEEN CAP MOUNT AND TANK!
B) the o-ring ( seal) sits on the pipe protruding from the tank ( big side down)
C) re-install cap ( be careful to get the new seal to snuggle into the cap mount bore)
D) re-install screws and tighten ( do not over tighten) I was missing the seal and one o-ring was split from the factory? Go figure!
When tank is full and it is hot out the fumes and small amount of fuel will vent thru the cap, past the little valve in the cap, back thru the pipe in the tank. If the seal is missing or worn the fuel / vapor can seep onto the tank and spew everywhere.

[dogdoc]

why did you order a o-ring in the first place? what problems were you having? gas spilling out? Hope you found it, sounds like our gasMD helped you out. :-)

[bobhamlin]

Originally Posted by Doc (Lonewolf)

why did you order a o-ring in the first place? what problems were you having? gas spilling out?

Yes. After I had filled the tank on a warm day. Strong leaking from the gas cap. After posting here on the board, the O-ring was the suspect. Some bikes seem to be missing theirs from the factory. I probably lost mine during dis/re-assembly from painting, since I had had no leaking prior to that. (But then again, I had only been riding the bike in very cold weather and warm weather seems to be a factor.)

[bobhamlin]

Originally Posted by rewindgy

Okalie dokalie!
<<snipped>>

I will put it in tonight and fill the tank tommorrow to the bottom of the splash guard -- and we'll see if the O-ring makes a difference.

Thanks rewindgy.

[rewindgy]

That was my problem - I could only fill to the bottom of the splash guard! Now I can fill the damn thing almost to the top with no ozzing! I have actually ran out of fuel and could not get over 4.5 US Gallons in it before - now I can put upwards of 5 US Gallons and I am not running out yet!

[dogdoc]

Mine does over flow out on HOT days IF I fill it above the flange, which your NOT suppose to do anyway. I was told the tank has an over flow and when it builds pressure it goes someplace, out the over flow tube and down the front pipe and bakes on. great. So I just fill her up to the flange only. When she does leak out, it very small amt, it doesnt spew everywhere. Does that sound normal for Nomads or missing o-ring too like Bob?? ::)

[rewindgy]

The gas tank overflow drain hose is down by the Oil filter on the 1600's. If I fill it now to about 1 inch from the top it will not spew out - if I'm over that level it spews in the centre of the bike where it is supposed to. At least that's what it does on mine.

[Yellow Jacket]

Here's a view of where the o-ring should be. Yellow arrow.

[caper]

Good picture . Thanks Bob