Scooter is in very nice shape.......just purchased, replaced sparkplug, changed oil, and replaced air cleaner as soon as I got it. Scoot will start right up when cold....idles perfect. But after a few minutes it does not want to idle.......dies when I try to ride it. How does one adjust the two screws on the carb....in what order?? I opened the bowl and drained it looking for dirt = none. What is the adjustment screw with tangs on it that will not allow it to turn more than 1 revolution??