Gas leaking from carbs into airbox

[robsGS850]

Gas seems to be pooling inside my airbox, slowly dripping out onto the engine below (can't be safe). What does this mean? Please don't say carb rebuild, please don't say carb rebuild [-o<

fingers crossed,
rob

[chef1366]

OK I won't.
Carb cleaning:-D

[Nessism]

OK I won't.
Carb cleaning:-D

And maybe a good tank cleaning if rust is causing your float needles to not seal properly.

[tconroy]

What they said. See I didnt mention carb rebuild or o-ring replacement in the needle valve seats which is probably what it is 99.9% of the time.

[robsGS850]

thanks guys. looks like I'm about to immerse myself in the mystical world of carburetors. I knew I couldn't avoid them forever 8-[ Gonna dig into the archives on here, then roll up my sleeves & get messy.

wish me luck

[Giblet]

Be sure you threaten to stuff a "gas soaked rag" into the tank before you do anything else. Usually scares my GK into submission \\/. Oh, and don't post that here. It tends to upset a certain GK owner in Arkansas .

Seriously though, you might also check your petcock also. The OEM vacuum operated ones are prone to leak, diaphrams go bad. Best solution there is a manual petcock. Make sure you get one with a "real" reserve setting. Needle and seat/o-ring are very easy to replace but you shouldn't rely on them to hold back the fuel flow. I'm told they are mainly designed to regulate fuel flow via the float. Mine leaked even though they had just been replaced. I now have a Pingle petcock and have had no further gas leak issues. 55K miles and as far as I know the carbs have never had anything more than needle & seat valve/o-ring replaced.

[ddominik]

Leaking petcock and carb floats

Newbie here "ddominik" go by Dom

Just picked up a 77 GS750 - nice bike in good condition (not original) and it LEAKS gas everywhere. So I followed the search engine and it lead me to this thread.

I need help in finding a parts source (in the US) to rebuild both the petcock and carb(s). I raced vintage MX (AHRMA) for the last 17 years and now find myself drawn to the vintage sport bike scene - easier on the back - same rush!!!

....for me - it's gotta have at least one chrome fender to qualify as a motorcycle .... just another "old guy's" opinion

Thanks in advance for the parts help

Dom
Bloomington Springs, TN

[chef1366]

http://cgi.ebay.com/ebaymotors/SUZUKI-GS400-GS425-GS750-GS850-GS1000-PETCOCK-KIT_W0QQcmdZViewItemQQcategoryZ35597QQihZ008QQitemZ180112877548

http://cgi.ebay.com/ebaymotors/SUZUKI-77-79-GS750-CARB-KITS_W0QQcmdZViewItemQQcategoryZ35597QQihZ008QQitemZ180113193933

[Alixn]

I own a 1982 GS750T, 55k km on it. Little history of the bike : It probably spent most of its life outdoors but since I've had it (7 yrs now), it always spent Winter indoors. 2 yrs ago I had the gas-in-oil issue and tried doing the carb job myself as detailed on gsresources.com, messed up the jets somehow and ended up having them done at a local shop.

Last Fall on the day of riding it to the garage for the Winter (I live in an apt), I noticed it was leaking gas from the airbox. I darined the gas from the tank and forgot about the bike all winter. This Spring before starting her up, I pulled the carb rack, cleaned out the bowls and floats with carb cleaner spray, inspected the diaphragms for wear/tear, put everything back together and the bike started on the 1/4 turn. For my 1st ride, I filled the tank with fresh gas and Penzoil carburetor cleaner additive. Many rides so far, no leaks.

Someone busted up my ignition button so I fixed that. I did a quick press-and-release on the button to test my repair, the starter came on, but I didn't bother to start the bike (it was sitting for about 3 weeks, bad weather + busted button).

This morning ready to ride to the job, I find a gas run on the parking lot starting from under my bike. Petcock is at ON position, throttle closed all the way.

So here's my questions : Could it be that my testing of the ignition button repair moved something in the carbs? The engine probably turned a bit when I did this but not much. As soon as I heard the starter running I released the button.

Also, I've removed the gas tank many times in the past, disconnecting all lines and I've never had a leak through the petcock.

[chef1366]

I would replace the petcock.

[Alixn]

Well... I got home this afternoon and tahdaa : gas in the oil. I can tell just by the sound when I try to start the bike.

Now I'll do an oil change, carb job and replace the petcock and probably never know what's causing this mess. *sigh* and this is such a nice week weather-wise... good for working outdoors I suppose.

Thanks for the advice. I'll keep posted on findings.

[bubba]

Where can I get one of those manual petcocks? Mine still is O.K. but why wait till it craps out?

[Giblet]

Some say they are too expensive but, I replaced my OEM petcock (which I kitted once, bad diaphram) with one manufactured by Pingle and haven't given it so much as a thought since. Sure you have to remember to turn the gas off but I figure there is a reason Suzuki doesn't use those vacuum operated ones anymore. I was told to the Pingle has an actual reserve function that is works like the OEM one, I'm assuming there are others that don't. I ordered mine off the internet, direct from Pingle, I think

[robertbarr]

Canned reply:

First, let me point out the obvious: If a carb (or carbs) are overflowing when the bike is not running, you have TWO problems. First, your petcock should prevent ANY flow; second, the needle valve should allow flow only up to a fixed height in the bowl (ie, not overflow). Excess fuel has to make its way past both of these parts.

(A third possibility on old carbs is for fuel to flow past the inlet seat O-ring. [n/a for VM]. That doesn't apply to newly rebuilt carbs, since the owner has just installed brand new. Right??)

I'm not 100% sure why some needle valves leak and others don't, but I'm starting to lean with Keith Kraus' suggestion, which is to use only OEM valves and seats. Simply because it works. The question why is a separate matter. (I have a theory, but no guinea pig to test it on at present).

For the petcock, you'll hear a number of suggestions. I think that the vacuum operated petcock should be kept operational, for a few safety reasons.

Several of the folks here are convinced that petcock rebuild kits are useless, and your only real option is to buy a new OEM petcock.

For now, for people who are 100% sick of carb overflow & the ensuing problems, the consensus then is to go with OEM petcock, seats & needles. it's expensive, but it seems to be the only certain way to correct this BS once and for all.

(I would add: no doubt there are people whose overflow problems began when they bought carb rebuild kit(s). The machining on the parts is often abhorent and inexcusably amateurish, and the f&^%#ing O-rings don't fit correctly. The consensus for a while now has been to buy gaskets IF you need them, valve seats & needles IF you need them, and an O-ring kit.)


The petcock does not, in any way, REGULATE the rate of flow. It should be either on or off. If you have overflow on a running bike, there's a problem with the inlet valve.

Either:

1) the float is no longer buoyant enough or is badly adjusted, or

2)the valve is bad, or is being held open by some foreign matter.

[Giblet]

Wondering, just what "safety" there is in a vacuum operated petcock. If they were such a wonderful idea (and they are, when they work) you'd still be seeing them on new bikes.