Re: Hooooooray I found the air leak!
The trick with using the 'O' ring in the carb throat is to apply a lot of pressure against it when tightening the clamp that holds the carb to the intake. Simply sliding the carburetor up against the 'O' ring doesn't assure a snug, airtight seal.
I've had very good results with Seal All although I will admit it requires some work if you ever need to disassemble things. It holds tight.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"