If gas is leaving, air has to come in right? Where?

overflow tube?

There is a vent hole in the gas cap.

yeah they are vented, you have an overflow tube and the gas cap should let some out too.

Mine equalizes with a bit of noise.  There is a harmonic droning sound that eminates from my gas gap.  Like rubbing your finger around the rim of a wine glass, but at about 160 db.  It was so loud once that my roommate came outside the house to see what the sound was.  I need to fix that.

160db...    A gunshot is like 140db.... wow.

trey

If you listen to it for 5 minutes, it will drive you mad!  Like the smoke alarm going off for 5 mintues, but worse!  Okay, maybe is just seems loud because it is at the very limit of human perception.  I started foaming at the mouth the first time it happened, until I popped the gas cap up with a "whoooosh!".  Crazy, man.  Crazy.

Yamaha gas caps sigh....it is weird when ya got 4-5 of them sitting in a shop all "sighing"

Gotta watch out for those tank bags.  We hear stories from time to time about people who are riding along and all of a sudden the bike dies, they get off, remove the tank bag, equalize the pressure, and open the gas cap.  Yup, still gas in there.  So they throw the bag bak on, start her back up, zoom away and 45 minutes later the same thing happens.  Bike dies, get off, remove the bag, look in the tank, equalize the pressure, start her up,............I imagine it could be a maddeningly vicious cycle if you don't know what's happening.

been there....
done that....

it f%$king kicked my ass for weeks

and i had used the tank bag on several other bikes.... :x  :x  :x  :x

wow,
i didn't know we had potty mouth mode enabled???

I don't see how my overflow tube is good for anything.  Every time I lift the gas tank I see it is bent/kinked at a 90 deg. angle.  It appears that the top of the carb causes the bending.

Anybody else witnessed/fixed this ? :dunno:

Quote from: John BatesI don't see how my overflow tube is good for anything.  Every time I lift the gas tank I see it is bent/kinked at a 90 deg. angle.  It appears that the top of the carb causes the bending.

Anybody else witnessed/fixed this ? :dunno:

Does it look like the hose in the diagram on my Fuel Hose Routing page?  If so, no worries -- that's actually the default shape of the hose.  The built-in bend near the upper end comes in handy when you're trying to identify which hose goes where at reassembly time.

If the hose is routed all the way over both carbs, and seems to be "extra kinked" as a result, you could try rerouting it up between the carbs.  But I don't think it matters either way ... as long as it reaches the overflow outlet tube.

QuoteI imagine it could be a maddeningly vicious cycle if you don't know what's happening.

No kidding. It's maddening for anyone who doesn't know what is wrong with their bike. I feel like a complete idiot when I figure out what is wrong after something doesn't go right.