I think the first motor he had was probably fine and I think the one he has now is fine. I will bet it's a tuning or airleak problem. So sr88
I would do exactly what Randy showed you(Firebird) and listen to Rich(Redharris) him and Adam made some really good videos they will help you tons the only way you could have destroyed 2 motors that fast is running way too lean and not breaking them in right I have 8 sh motors and alot of them have had more than 2 gallons through them. They are a very good motor.Edit: Are you using airfilter oil too? Judging where your from guessing you run in the sand abit, I hope you get things figured out we are here to help ya.