Leaky carb

[jpderoy]

Hi
I have a 78 r80/7 and she consistently leaks fuel from the right carb. I have rebuilt that side and everything was clean, a few o-rings were shot, but even with new ones she still leaks. Normally there is only a little residue on the bottom of the bowl, and my right shoe smells of gas. Today I watched it, and there was a burst of fuel as I opened the throttle full. Is there anything I am missing, or is it a common thing on these bikes? The float bowl gasket is brand new, and there seems to be no leaking around it. Could it be something with the jet needle? As I said, everything was very clean in there. I appreciate the help.
Thanks
JP

[kbasa]

Sounds like your float needle is sticking. You might have a little piece of crud stuck in there.

The float needle is a little gizmo that works with the float to allow gas in when the float reaches a low level. The needle opens up to allow gas in and when the float rises high enough, it shuts the fuel flow off.

[AntonLargiader]

There's nothing I can think of in the carb that would cause it to happen when you open the throttle, so that part may be coincidence. Nevertheless, the solution will lie in the float valve assembly. Remove the float and needle and inspect the seat, Wipe off the end of the needle and look for a groove in the tip; if you see one just get new needles. Lastly, make sure the float level is set correctly. There's a real offchance (I'm really talking minute here) that fuel is leaking between the carb body and the needle seat, but it's not really worth considering.

[boofer]

Lastly, make sure the float level is set correctly.

If the float level is set too high, fuel may be coming out the overflow. Under acceleration you might have some wave action helping cause this. Just a thought.

[Red100RT]

My R100 had the same kind of problem not long ago and it turned out that the pin that holds the float was very slightly bent which caused the float to bind just enough to cause gas to flow past the needle valve. Remove pin and roll on a flat surface and look for any rough spots while you're at it. Oh, and also check the hinge tabs on the float as well. Doesn't take much to stick the float.

[DennisDarrow]

On a lot of the older models, they used a foam float which absorbs fuel and gets heavier, thereby causing overflow. Perhaps changing out the float itself?

Another problem could be contamination in your fuel tank. Small particles of crud reside in your tank that get by the screen in your petcock. Anything in your bowl as you remove it? Often times if one removes the bowl, turn on the petcock to let fuel flow and jiggle the float a couple of times will cure this......Dennis

[jpderoy]

Thanks everyone. Found it was just that the float needed tweaking, and after a few tries she's all dialled in. While in there I did a valve/timing tuneup and wow! What a difference!