I got my son a 2002 XR50 that he never gets off of.. It just recently started to act up.. Once the bike is started it idles normal for about a min then idles real high for a couple mins then idles back down.. I tried the idle screw and didn't help.. What is the screw next to it for?? Is it for the flow of the gas to the carb..Sooo I dunno if its the float or not.. Or if it even has a throttle position sensor...