yes...in is definately raising idle. As far as the carb sinc. I have always removed the carbs when doing this as it enables me to see what is going on. sometimes you can get away w just removing the airbox also. Once you are looking in the carbs you want to have all three[or 2 if twin] carb slides to arrive at top of carb at same time when maxing the throttle. When done,tighten the locknuts on adjusters[located on top of carb] and then reinstall.
You should also find the mixture setting and do this at same time[turn them in all the way then back off # of reccomended turns...usually 1 7/8-2 turns on skiddoo]
Then your off to the trails