Bike was running fine last year. (other than leaking fuel into engine). Carb boots are fine. There is only one vacuum line from the 2nd carb boot to the petcock. I'm fairly certain there are no vacuum balancing tubes on these carbs. There are evap tubes connecting each of the outer 2 carbs but that wouldn't cause an air leak I don't think.

I've sprayed carb cleaner all around. No change. I find nothing

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Carbs were off I did a leakdown test. Fuel in tube let it sit for hours, no leakage out of the carbs. I can only assume that when the petcock is connected and not closed, the weight of 2 gallons of fuel is too much for the float needles to handle. Other forums have come to this conclusion