rich idle running, but sometimes its normal when the engine is not hot enough.
The reason is easy, too much fuel gone in on the bleep and when you shut the air going in to the carb you still have a bit of unburnt fuel in the manifold, causing it to idle low and climb back again after the fuel air mixture normalizes. best way to tune is to ride around until the engine is at operating temp then park the bike with the engine running, then bleep the throttle and play with the idle mixture screws, be aware that the rear carb might cook your hands.
do 1/8 turns a time on both of them and 1/2 maximum in or out will be the adjustment from stock setting, after you are happy with the setting let the bike idle for 2 min then kill the engine and cool down to examine the plugs to see if the mixture is ok for idle.
NOTE! this will only be helpful if you have two carbs balanced. it has happend that the carbs were not balanced and one cylinder was dragging the other cylinder. as a plus it will be better if you had a vacuum gauge hooked up during the tuning of the idle mixture screw because it does have a play on the balance also.
