Overflowing carbs - what can I eliminate?

[wirehairs]

Sorry for another question!  After installing new o-rings throughout my carbs, I now have one of them appearing to overflow through the overflow tube when I start it.  But here's the rub: it's infrequent and there's no rhyme or reason.    It will also usually stop within in 10 seconds or whatever.  I'm waiting until it does it again so I can be sure of which tube it's coming out of before I pull the carbs to diagnose. 

Because it's not a continuous problem, what causes can I eliminate?  I do know that I made a mistake by not remeasuring the float heights after changing the float needle o-rings.

[Mark Olson]

you already know what you have to do.... float heights. 

[JPaganel]

Oh, floats, how do I hate thee...

There is a thing that I found that will screw you up every time.

Floats bend if you so much as look at them wrong. What often happens is that what bends isn't the tang, but the whole float frame, and the floats wind up at different heights. Result of this is that the level isn't where you think it is.

Check floats and make sure both sides of each float are at the same level before adjusting.