[strike]I had a similar problem on my KZ440, one of the carbs had a slow leak out of the overflow nipple. I knew it wasn't the float level, because I adjusted it way below where it should have been. it turned out that one of the overflow tubes was cracked. I covered it with some epoxy and now it's fixed. Check around the overflow tube, or take the bowl off and fill it with gas and watch for leaks.[/strike]
Never mind, I didn't read everything here. It does look like it's the float level, and that float needle spring looks like its stuck.
