Gas Tank Noise

I went out practicing on my bike last night and after I got back noticed a hissing sound coming from around the gas cap. I opened the gas cap and and it sort of 'sucked' in a bunch of air.

I closed it up and came back out to the garage after changing out of my gear and it was making the noise again. Any ideas on what might be going on? I've never noticed the problem before but I've never run the bike very long before. It was pretty hot by the time I was done last night.

Is it possible that I got overzealous when re-sealing my gas cap and sealed the vent? If so, how can I test and subsequently fix the issue? But, if that is the case, why would it have just started?

Yes, the vent is NOT working on your cap. Don't know what you did to "reseal" your cap butit did not work. Recheck it and correct it or maybe get another one from ebay. Riding your bike like that will leave you on the side of the road until you pop the cap for the ride back home!

Did you replace the rubber gasket? It's a common part for a lot of Kaws and cheap. Not worth fixing if that's what you tried. Try and run pipe cleaners or wires through the venting and see if it cleans it up.

Thanks Ya'll.

I actually took the entire gas cap apart and replaced all the seals/orings I could find. I seem to remember one of them not fitting just right though...where is the vent at so I can check?

Sorry, can't help you there. My cap works fine and I've never taken one apart. Maybe someone else has? :huh:

Well I don't know your cap specifically. When I took mine apart to replace the gasket there were metal parts that had a groove, or hollow tubing going partway around the edge. I really can't remember, but that groove/tubing is the vent. It can get clogged with rust, dirt, whatever.

Thx again guys...I guess I'll take it back apart and replace the o-ring with the original one and see what happens. If it leaks after that and I can't find a correct sized replacement, I'll just buy a new cap.

Wouldn't having a vent make your gas mileage lower? If it is evaporating out all the time that could be an issue?

Little B

The venting is not an issue at all, all cars nowadays have vented gas caps. There should be a couple of decent caps on ebay if yours is shot. Let us know...

Well, I pulled the gas cap and found that the silicone stuff I used to seal the new gaskets with had turned into a nasty gel like stuff.

I pulled them off, cleaned the parts good and replaced them with the original gaskets. While I was in there I went ahead and put the original O-ring back on where the locking mechanism seals against the venting area.

So, the next time I go for a ride I'll know if that fixed it. I hope so...not really wanting to buy a new one right now. :ohmy:

I don't believe there is a silicon made that stands up to gas or gas fumes! Stay away from the stuff when it comes to gas. Let us know if problem fixed!

Update after yesterday's ride:

No more gas cap issues at all! Cleaning her up and replacing the original interior gaskets and O-ring did the trick. And, it doesn't leak either! :woohoo:

Thanks for the help everyone!

Enjoy the ride!!