Cylinder flooding on 91 GS after carb rebuild and petcock confirmation

[neocryptica]

Hey all,

Having an issue and at whits end.  I bought a Clymers manual and have been rebuilding my 91 GSE.  Had her running (even rode her to work for a few days), but I am having an issue where the left cylinder is flooding now.  I am new to bike mechanics, but have been trying to put in my due diligence on making sure I research and do the leg work up front.

So far I found that if I remove the left plug, clean it off, use compression to blow the gas out of the cylinder, then replace and start, it runs fine for a few minutes, then starts flooding again.  I have replaced the plugs, tested to make sure the petcock is not stuck, cleaned the carbs and replaced the needles, and even turned it over to a friend who does bike mechanic work...neither of us can figure it out...

My only thought left is that maybe I (and he, when he worked on it) didn't get the needle adjusted properly and it isn't shutting off fuel flow properly, or the float is sticking.  I haven't pulled the float bowl with it on to confirm the floats are actuating properly, but will be doing so tonight.

Can anyone provide some extra insight on this?

[adidasguy]

Left carb has stuck floats so gas just keeps flowing and never stops.
Could be other issues, but the floats are the only thing that stops/controls the flow of gas into the carbs.

[BockinBboy]

You can confirm its the carb float/needle valve and not an electrical issue quickly by the clear U-tube float height check.  Put a piece of clear tubing on the carb drain and bend upwards in a U-shape.  Set petcock to prime.  Open carb drain screw.  Observe the level the gas rises to in the tube.  If the gas goes above the carb bowl gasket height, then its an issue within the carb.  If the gas remains at carb bowl gasket height, then its an electrical issue.

... by the description though, it sounds like the needle valve isn't seating properly... now whether that is due to float set too high, wear on the needle valve, or something stopping it open... you won't really know till you open it up and check it out.

- Bboy

[yamahonkawazuki]

You can confirm its the carb float/needle valve and not an electrical issue quickly by the clear U-tube float height check.  Put a piece of clear tubing on the carb drain and bend upwards in a U-shape.  Set petcock to prime.  Open carb drain screw.  Observe the level the gas rises to in the tube.  If the gas goes above the carb bowl gasket height, then its an issue within the carb.  If the gas remains at carb bowl gasket height, then its an electrical issue.

... by the description though, it sounds like the needle valve isn't seating properly... now whether that is due to float set too high, wear on the needle valve, or something stopping it open... you won't really know till you open it up and check it out.

- Bboy

yup. both addy and Bboy have it on the head. it does seem to be the left float per description. test using method previously posted, let us know Eh? , very few things bring a gs to a halt. but this is one . but minor. when she runs, she runs fine right, UNTIL the flooding correct?

[neocryptica]

bought and installed new carb rebuild kit, just to make sure the needle is good and the gasket, o-rings, etc...aren't crispy.  I confirmed that it is the floats, so tonight I will be pulling it back apart and adjusting.  I have a buddy who is a gear head from days long past that is going to "call me a liar" on everything I have done and check everything over 

Hopefully I will have a fully functional fun-cycle come the morn

[yamahonkawazuki]

you soak the carbs overnight?