Sorry for all the carb questions lately guys I'm slowly figuring out how to tune carbs. Anyway I've noticed as I turn my idle screw in to adjust the idle the carb begins to whistle. If I back it off the whistle goes away. Is it because the primary blades are opening too far? I can't get good idle quality from this thing to save my life. I ordered a new rebuild kit from summit and it should be here tomorrow. I think my power valve is part of the issue. I have a new 4.5 on the way. I have 9 Hg at idle @ 900 RPM. I'm going to take the whole thing apart and clean the heck out of it and see what I can get. What's causing the dang whistle?