Originally posted by Parkerm
Check needle valve, I have seen needle vales that leak enough air to take the engine lean. It is an intermittent problem in some cases.
I really think it is the needle valve. But I put a new O-ring on today. LESS bubbles, but still some; you know what? I put TWO O-rings on, and the bubbles stopped altogether, but then I couldn't screw the needle valve far enough down to lean it out. So I know there is only supposed to be one O-ring.
I wonder if this problem would have ever developed if I didn't take the needle valve out (which I had to do to cut out a cowl for my Cub)