Your float seats are without individual filters so if a teensy bit of crud comes loose it'll hang up at the sealing surface and hold the valve open. Remove the needles and flush filtered gas through. If this doesn't fix it you'll need to replace the needles and/or seats. Use high-quality (ie Keyster) rubber tipped needles. Never put unfiltered gas through them, and use new fuel line. Once they're tight they'll stay that way for years to come.
(Admin: remove this line if it's verboten to hawk wares but I've got orings, float parts, etc.)
Let's also ensure that the float heights are correct.
Not knowing to what extent you tore them down, it's never a bad idea to make sure that the jetting and needle clip positions are correct for what you're doing, and that the small passages are clear.
And of course the one thing I preach to everyone is to have a look at your compression. (And valves, and timing...)
I know we're getting far afield of carbs, but around here we're focused on the long haul.
For example, a guy can install pods or drag pipes without sufficiently richening the carbs. He may THINK that he's running just fine in a lean condition but a year later he burns a valve.
Down low we can be a tad lean for easier starts and take-off response but up high we want to be rich just this side of losing power. It's a balancing act of sorts but it'll keep you going longer.
OSC
www.oldschoolcarbs.com
There are 10 kinds of people in the world---those who understand binary and those who don't.