Buddy's bike is leaking gas into airbox

[Gsxxx600]

Hey all,

Its been awhile since Ive been on...lots of school work.
Any case, my friend has an 85 Seca or so and its been sitting while hes been in school, so we tried to start it up but gasoline started pouring into the airbox.

He has a four carb setup...we can actually start the bike and run it, but the pouring gasoline might prevent us from riding lol

Im assuming one of the needles is stuck, or theres a problem with the floats?

Thanks

[Flank]

That cant be good.

[Gsxxx600]

any ideas?

[md86]

Yeah , probably SOMETHING to do with the floats/needles . Leaks gas out of the airbox ? Does it leak on prime or on while the bike's not running ? You'll probably have to take the carbs off to fix them , but SOMETIMES you can get away with tapping the float bowls with a screwdriver or something to "unstick" a float . But when you take them off , you're looking for floats that don't float (put them in some water and see if any bubbles come out ) or have gas in them (means there's a hole in it) . You'll also want to look at the needles and see if there's anything in that area that might make them not close all the way . Doesn't take much . A bike that old MAY need a carb rebuild kit , which would probably be the easiest way to deal with carb problems ...

[Gsxxx600]

I'd have to agreee...the gas only leaks when you try to start it, not while its sitting.

Thanks for your help, i was looking for a summer project..lol

[The CyberPoet]

Re: Buddy's bike is leaking gas into airbox

85 SecaII... gasoline started pouring into the airbox.

Drain the airbox and wipe it out with a paper towel.
Check the vent line from the engine to the airbox; what you may assume is gas from the carbs may be gas that's leaking past the rings and being returned to the airbox as vapor when the engine is running. If so, you'll need to change the oil and have a leak-down compression test done to figure out which cylinder has bad rings. If not:

Check the oil for presence of fuel; if the oil fill smells like gas, change the oil and see the note above.
Remove the carbs
Disassemble the carbs.
Clean the carbs and check the motion of each float. Odds are one will be obvious in the fact that it's stuck. Clean some more. If you can't fix it, scour eBay for replacements.
Reassemble and retest.

Good Luck!
=-= The CyberPoet

[Gsxxx600]

update:
We never got the chance to take apart the carbs to see if they needed to be cleaned/diagnose. We tapped the top of the carbs with a mallet a little bit, should we have tapped the top, or bottom though?

I feel like a complete fool when it comes to carbs, bc I have no idea what a float, bowl, or anything like that is...odds are we would take them apart and we might not even notice what the problem is.

In any case, we were messing around with it and removed a hose that connects the front of the airbox to what appears to be the transmission cover. When removed, gas pours out of this nipple (from the cover) like a spout...what can that be? It might be oil, but it wreeks like gas...so I do know an oil change is in need, but dont want to do it until we fix the gas leaking into the airbox...

please help!

[The CyberPoet]

update:
In any case, we were messing around with it and removed a hose that connects the front of the airbox to what appears to be the transmission cover. When removed, gas pours out of this nipple (from the cover) like a spout...what can that be? It might be oil, but it wreeks like gas...so I do know an oil change is in need, but dont want to do it until we fix the gas leaking into the airbox...

It's gas from a stuck float bowl. Basically your carbs are leaking fluid into the cylinders, it's going down into the oil, heating up as a vapor, being sucked back into the airbox by the vacuum vapor recovery tube and then recondensing. Less often, it actually flows backwards as a liquid through the airbox stack.
Definitely time to dig into your carbs. You'll want to look at doug771's carb float page for a good learning experience on carb floats and how to check/set them.

You'll need to change your oil after you get the carbs fixed -- the gas is tearing it down and ruining it very quickly.

Good Luck!
=-= The CyberPoet

[Gsxxx600]

ur the man cp!

[Gsxxx600]

so, i took the carbs out today, and examined the floats...all appear to be working well, none are stuck.

By saying none are stuck, i mean they are free moving as in when i push the floats up, they bounce back down...

am i missing something? I cant think of anything now, all looks good. Can there be a tear in the piston valve? (that rubber boot that slides up and down inside the top of the carb.)

thanks in advance

[The CyberPoet]

Go read this thread as well:

http://www.katriders.com/forums/viewtopic.php?t=6724

May turn out to be the same basic issue.

Cheers
=-= The CyberPoet

[Gsxxx600]

thats interesting...one of the gaskets that connect the float bowl to the carb is dry rotted, and cracked, perhaps thats the problem...

ill have to look for the o rings, i dont remember coming across any in his carbs tho

[Gsxxx600]

or is it possible that at one point, his floats were stuck and by hitting them with a hammer it worked...but it still had the same problem, which is why we took them apart to find all the floats worked... so can this mean that if the gas is mixed with the oil inside the engine, that would then mean too much fluid is inside the engine (assuming the oil was filled to its fullest), which would result in the gas/oil mix still to pour inside the air cleaner, bc it has no where else to go?

Perhaps after the oil change, and knowing the carbs are in good shape, all might be well, or am i being too hopeful?

[The CyberPoet]

or is it possible that at one point, his floats were stuck and by hitting them with a hammer it worked...but it still had the same problem, which is why we took them apart to find all the floats worked... so can this mean that if the gas is mixed with the oil inside the engine, that would then mean too much fluid is inside the engine (assuming the oil was filled to its fullest), which would result in the gas/oil mix still to pour inside the air cleaner, bc it has no where else to go?

Yes. if there is fuel in the oil, it will always migrate to the airbox once the engine comes up to temp, because fuel boils off at much lower a temp than oil... the question is strictly how much of it will sucessfully be pulled back through the intake to burn off and how much of it will condense in the airbox. Anytime you have a carb leak, you should change the oil (including the oil cooler) before running the bike again (and put a teaspoon of oil in each plug hole -- as the fuel eats away the oil barrier at the rings).

Perhaps after the oil change, and knowing the carbs are in good shape, all might be well, or am i being too hopeful?

May be the case. You won't know until you test it to try it out.

KNOW THIS:
since all oil changes only change 65 (sans cooler & filter) - 85% (with cooler & filter) of the oil in the engine, at least 15% will always be left behind unchange -- and will still contain fuel to vaporize off. Get the engine good and hot right after the oil change to boil off any additional fuel and/or change the oil again.

Cheers
=-= The CyberPoet

[Gsxxx600]

ill keep you posted
]
one more question...is it neccesary to change the air filter? or just let it in the sun to dry out, some gas got into it...the air filter is a couple months old, so its very clean