when you have your sync tool hooked up can you turn the idle down to 1000 and how does it idle? may be one of the plugs or hoses on the carb is leaking air throwing the idle mix off. I also ride a couple or more mile just before I sync the carbs so the motor is nice and warm and the carb heaters turn off. don't know why they always come on when I first start even when its 70+ degrees out. two min of idle will usually turn them off.