coilover,

You might slap me when you hear my take on the question. The carb that is closed on full choke is taking in almost pure fuel...little air. The other carburetor, which is open, is only flowing enough air for it...it can't double its flow to make up for the loss of air on the choked carburetor.

It is not as if the system is now working on one carb because one is blocked off..the blocked off carb is dumping tons of fuel without tons of air.

If this makes no sense, E-mail me a big old SLAP.

Stuart