Spitting gas out of #3

[Alan Schlosser]

Ok. Need the advice of the resident sages.
Nephew has an 82 750T. Started running poorly the other day. Saw some gas coming out of the vent tube on the air box. Thought it might be spark.
We did the coil test and found a high resistance on the secondaries of that set. Cut back the wires a bit and reinstalled the plug caps. That got us down to the 32K range which is good.
Fired it back up and all cylinders are hitting now and the pipes are hot.
Problem is that once it's running and looking in the airbox, you can see that fuel is spitting back out of the #3 carb. So now we need some suggestions. Carb? Diaphragm?
The petcock seems fine. Pull the vacuum line and there's no gas in it. Suck on it and fuel will turn on and off so I don't think the petcock is leaking into the vacuum line.

You're thoughts would be appreciated. He's going to do a compression test tonight just so we have a baseline of good compression and spark....

 

[Nessism]

Alan, sounds like #3 has a stuck float needle. If the carbs haven't ever been rebuilt with fresh O-rings I'd do it now. Cycleorings.com sells a kit. Sometimes the float needle seat O-ring fails which allows fuel to over fill, sometimes rust and gunk from the tank blocks the float needle from seating, and sometimes the needle or seat just plain wears. The only way to know what's going on is to split the carbs and have a look. Carb rebuild tutorial is linked in my signature and I suggest you have a peak...

 

[chrisbock]

Hi There. This is my first time posting. I've been trying to find a thread about this since the fourth, and i'm glad I got the correct wording finally! I've had a similar problem with my '81 GS850. I've been having an issue with acceleration recently (bogging down feeling when twisting the throttle) and then on a ride, my bike stalls. I saw there was copious amounts of fuel coming out of the carb filter pods on my 1 and 2 cylinders. My first thought was a coil going out, but after checking the Haines Guide, realized that the coils go to 1 and 4, and 2 and 3. Could both of my float needles have gotten stuck at the same time? Thanks, and sorry if this has been written elsewhere, 'cause i couldn't find it.
Chris

 

[loud et]

Yes guys it sucks to have to break your carbs down during riding season, but after you do your first real carb disassembly, dip , blow out with compressed air , new o rings from cycle o rings (14$) and reassemble ....you will be very confident with the procedure. It all seems greek the first time, but after that it gives you real confidence to work on your bike.
Use the links from Nessism and Cliffs page and you can do it right. I just did my second set of carbs and I did not even need to look at the tutorial. Carbs seem so intimidating but the MIkunis are actually very easy.
Plus it give you the oppornitunity to get cheaper bikes with carb issues(as they always have) and get them running like the PO never could.
Good luck.

 

[chrisbock]

So, clean the carbs? That is good advice, but just for clarification, is it strange that two carbs would start spitting out gas from the filters at the exact same time? I was curious if there are any other causes I should be looking for.
thanks,
chris

 

[cowboyup3371]

If the floats aren't set correctly or orings not replaced than no it's not strange. This work MUST be done if you want that bike to run the way it should.