1982 GS450T Spewing Oil/Gas from Carb

[ADKCafe]

Greetings!

I bought a NR GS450T over the winter as a project and have been picking away at it in the snow. I've had it fired up briefly a few times under full choke and at idle. The first time one of the cylinders was not firing, but then it came on.

Today I started the bike under full choke and after about 5 seconds I noticed a growing pudding under the engine. I killed the engine and hopped off. petcock-side carb was covered in a oil/gas mix, as was the airbox, the wiring immediately above the carbs, and the top of the engine.

I started the bike two more times, and was able to get an 8 count before a frothy oil/gas mix starting coming out of the top of the carb, like thin coffee boiling out of the top of a pot, looking as if it is under pressure. It seems to be coming from around the gasket at the top of the carb and possibly from around the choke lever. HELP! Here's some more info:

Left side carb (as you look at the bike from the front) is fine
Right side cylinder did not fire immediately first time started, but did on next few tries
Bike is only running for a few seconds, but a disproportunate amount of
gas/liquid is coming out, but it stops when the engine is cut
No apparent leak from petcock, bowl gasket, or from the overflow lines
There may be leaks from the airbox to the carb, boots to the engine look OK
During the leaking both cylinders were running, RPM does not appear to
matter
Checked the case oil level, looks OK
Nothing coming out of the tailpipe (from two stroker days)

I have never seen anything like this before. Only guess I have is cylinder is actually not firing and is actually pressurizing gas backwards and it blows out of the top of the carb as path of least resistance. Oil could be bad rings?

If you've hung with this lengthy post, thanks a bunch and any info would be helpful. This is my first Suzuki, I've always been a Honda thumper guy.

[katoranger]

Is there gas in the oil? Might be a carb float sticking an gas leaking down into the crankcase. Was the oil level over full? Was the petcock left on prime?

Allen

[ADKCafe]

Is there gas in the oil? Might be a carb float sticking an gas leaking down into the crankcase. Was the oil level over full? Was the petcock left on prime?

Allen

The oil level does not appear to have changed and no noticable gas smell. I have been reading posts for the last hour or so and have learned quite a bit about the carbs for this bike. I did leave the petcock on prime for the first start attempt but did change the petcock to run for the second and third starts.

I think I may have a float problem, but I still can't figure out the pumping, frothy oil/gas mix going out of the top of the carb. Also, I would think that if the float was stuck the gas would be coming out the line, not going through the top. Still got alot to learn. I've got the bike on the centerstand now with the petcock on run. Going to give it some time to drain out and try to start in the next day or so.

[Nessism]

Sounds like a stuck float. I'd take the carbs off and make sure everything in there is looking hunky doory before going any further. No sense in dumping a bunch of raw gas down the crankcase if you don't have to.

[ADKCafe]

1982 GS450T Spewing Oil/Gas from Carb

I've continued to read posts about various carb problems folks are having, the post about fuel blowing into the airbox of a GS1100 rung a number of bells. So, I think I have a plan of attack:

1) Check the vent lines from the carbs to make sure they are unobstructed.

2) Check the petcock to make sure there is no gas coming through with the petcock set to "on"

3) Change the oil

4) Check the float bowl on the #1 carb. Going to have to do it insitu, the airbox on this bike is *not* coming out. I can't even figure out how they got it in there in the first place.

It seems like there are a lot of folks out there who have had carb problems with their GS's... Is there a story here?

[katoranger]

It looks like we are working on similar bikes. I haven't even gotton into the carbs yet. Just bought a can of carb dip today and I ordered some orings.

I am not a carb expert either, but it sounds like some pointers have been given.

Allen

[nabrams]

The airbox does NOT need to be removed to get the carbs out. It is a pain, but it can be done and is described in the manual.
Your problem description definitely warrants a full-fledged carb disassembly and cleaning.

[earlfor]

With frothing oil, I will bet the petcock is leaking and there was water in the gas tank and you probably have water and gas in the crankcase. I will also bet your crankcase oil level is overfilled.

Earl

[Billy Ricks]

Stuck float isn't the only culprit with this type of situation. There are o-rings on the float seat that dry out and shrink. I'd replace them while I was at it.

[ADKCafe]

1982 GS450T Spewing Oil/Gas from Carb

This morning I wheeled the bike out and began to clean it up. Decided to drain the oil, lo and behold about a gallon of gas/oil mix came pouring out! I allowed it to sit for about two hours to be sure, then rinsed with oil before closing the drain and filling with oil.

Got things cleaned up on the carbs and cases and then proceeded to gingerly tried to start. The bike fired immediately and began to rev. high. Cut the engine after a few seconds. Second time backed the choke completely off, fired just fine and set into a smooth idle (no tach, but sounds good). Ran for about 1 min, no spraying fluids, no noticeable leaks.

Next step I think is to do the starter fluid check on the intakes. Boot from the airbox to carb is damaged on both sides. Since I am without manual, what is the trick to getting the airbox out of this bike? Previous owner obviously couldn't do it (hence the damage), and I am a bit mistified myself.
Gotta get a manual soon, but my budget is tight and fork seals are trumping manual right now.