Possible air leak - replace the O-rings between the intake manifolds and cylinder heads.
Those carbs have "air cut valves" - to prevent backfiring (popping) on deceleration.
The diaphragms get stuck from bad gas.
The ports on the covers get clogged with bad gas.
If you cleaned the carbs yourself - that would be the first thing to check.
http://www.powersportspro.com/pages/home/default.aspx
Go to - your bike - Carburetor Comp 1 - #12 Air Cut Valve
carbs are not synced correctly. Make sure your engine numbers match the frame numbers, could be carbs from a different year range. I had a lot of difficulty with my carbs till i noticed motor was from different bike.
