Need some advice on setting the high speed needle of my motor... I'm wanting to get it "perfect" as possible. When I rebuilt the carb, I gently seated the needle and backed it off 2 turns. Motor seems to be doing OK at this setting, but could probably be fine tuned a bit more. How many turns is the needle supposed to be set back when doing a readjustment and how do I know I got the correct fuel/air mix? Thanks.