Fouls plugs at idle and backfires

[Bansheeman1121]

Ok as a;ways the banshees actin wierd, first off i got stock carbs no tors when idling the plugs turn real black and foul but when your ridin say down the street and on it the plugs are good color. Second when shifting and under hard accelration it will backfire and cut out same with when ur idling in nuetral it will backfire when you rev it out, just replaced reeds becuase thats what i thought it was i just cant figure this bull shit out the carbs are spotless inside jets all clean wtf is goin on

[Snopczynski]

carb slides backwards or choke crossover tube not connected?