To be honest, I flew it the day before and it ran great, I filled it up that night and started her up and ran fine, went to my flying site the next morning, it was around 30 degrees, ( my planes are kept in the basement. So there not outside, it went to fire then heard a odd noise and my hobby shop took the head off and low and behold the piston locked. I will take your suggestions and order a ST 45 now, I know I will toss that evo or just save it for my avistar that has a OS 40 lA. Thanks fellas.