Chasing Problems > Carbs > Valves > Back to carbs...

[praefex]

Hi All --

I've posted a few times in the past about my carb problems and not being able to maintain idle. Revs up great then lowers down and dies. I adjusted the vales on the bike (They were terribly tight) and voila the bike seemingly runs GREAT! I couldn't have been happier until I rode it around for a bit and realized that the float bowls were overflowing and coming out the Evap lines, etc, etc...the gas was also coming out the slow air screw (?), the right side hole on the intake side.

So this left me puzzled. I checked float, seemed high. Lower float tabs, same result. Severly lowered the tabs just to see if I could stop gas flow, same result. Everything I did yesterday-- resulted in the floats overflowing. The result of all this is when I put the bike back together to test, it cranks for about 40 seconds, then fires up with the choke on. Runs for about 30 seconds, then the idle slows down, down, down, dead.

So my next plan of attack will be to replace some part of the float system, but I'm unsure right now. Should I redo the needles? The floats themselves? Please help!!

Thanks,
Matt

[ducati_nolan]

Sounds like you need a rebuild kit. It's basicly some o-rings and the float valve. I bet your float valve has gotten worn and no longer will stop the fuel flow when the floats rise. To check this, take your float bowls off the carbs while they are still on the bike (if you can) and put the petcock on prime. Fuel will dump out but should completly stop if you raise the floats by hand with very light pressure. If they still leak they are bad or there may be dirt/rust keeping the float valve from seating.

I always recomend putting a fuel filter on your bike to prevent this problem. Try cleaning the carbs again and putting on a fuel filter on there first but you may need a new float valve.

As for fuel leaking out of the slow air screw (or idle mixture screw) I think there should be an O ring on there. Look at a good diagram and make sure all your O rings are in the propper place.

Good luck 

[praefex]

Ahh -- that would be a great test.

I just installed a fuel filter yesterday as part of my mods to get the bike working perfectly.

I'll try the float technique too and see what happens.

Thanks!

[scratch]

Lowering the float tabs allows the floats to close later, or rather keeps the float needle from closing.  Try raising the float tab.