tri carb help

[kip younger]

I finally got my three dueces on, connected and running!!!! But, when I rev the engine to the point that the secondaries open, the center carb will Pop or backfire as they first open. If I rev it slowly to the point of where the secondaries will begin to open, then the engine "bogs down - or hesitates. I have heard that the floats in the fuel bowls must be set exactly right or the secondary carbs can be too lean or rich... Is this what would cause the center to backfire? Any ideas are greatly appreciated. I'm so close to getting these things running... thanks - kip