Just bought a 2007 PW50 for my daughter. Oil injector was disabled, mixing Yamalube @ 32:1. After riding for 15 or more mins, bike loses power and begins running very hot. It has substantial top end noise, but otherwise appears to be making adequate compression. The main jet appears to be stock @ #70. Plug is bright white, so I know we have a very lean condition. She is just beginning, so very little WOT, and a lot of 1/4 to 1/2 throttle usage. Should I go up a size or two on the main. The needle in the carb has only one groove, but I found a needle on fleabay which is advertised to be for this carburetor and has several grooves which allow clip/needle adjustment. Please post any ideas. Thanks in advance, Matt.