I was wondering if anyone out there could help me? I have a 1980 or so QT50 Yamahopper. It starts every time. After letting it sit for 20 minutes or so it starts and then I can ride it for like 5 or 10 minutes just fine. Then after that I go and turn the throttle and the engine bogs down and then stalls. I have cleaned the Carb. Could the petcock be causing this problem? Thanks for all of you help!!!