What affects float level?

I just rebuilt the carbs on an '86 Honda twin with Keihin carbs, and I think
I did a pretty fastidious job of cleaning and re-installation, but who
knows?
Anyway, the bike doesn't idle worth crap, and although the left hand plug is
tannish to white, the right plug is showing a very rich condition. Before
tearing them out of there again (its an old 450 rebel, and there's very
little clearance for removing the carbs and for re-attaching the throttle
cables) I thought I'd rule out some basic stuff. In doing so, I checked
float levels the old fashioned way (with clear plastic tubing on the drain
tubes), and sure enough, the right carb is showing the gas in the bowl to be
almost a 1/2 inch higher than the left carb. (yes, the bike was level at the
time). Seems unlikely the float needle is stuck, otherwise, I'd expect
some significant overflow. The float seemed fine at rebuild (not
waterlogged). Is it possible I just tucked the float needle under the tang
incorrectly and so the float gets higher before the needle closes?
What else could cause higher levels in a carb like that?
thanks
Brent

 

OK, thanks mark.