Fix the obvious problem first. The carbs are overflowing so start there. You say "super clean" but did you replace any parts? You either have one or more float valves sticking, or the float height adjustment(s) are off. If you did not replace any parts, then I highly recommend replacing the float needles. They have a little spring behind the button that rests on the float and this little mechanism tends to gum up over time. Also the rubber tips tend to harden with age and don't seal as well. There are kits available that have just the float needles and bowl gaskets. I have had to do this to my K8 to correct overflowing carbs. Did I mention that I highly recommend it?
Don't forget to check the float "droop" after setting the float height.
While you're at it, order some new spark plugs and check the resistance of all four plug caps. They should all be less than 10K ohms and they should all be within 1K ohms of each other.
EZPZ
