I think it may be an air leak in the front bearing. I pulled the motor to check all seals and when I turned the crank by hand I felt a slight tick. Pulled the crank and a bearing shield came out as well. [:@] The fuel I'm running is 15% and 16% oil with 20% of the oil being caster. The fuel works fine in my other gt so I don't think its that. Either way I think I voided the warranty by pulling the motor apart so I may end up just buying another one or a different motor because the parts for this thing are outrageously priced.