This always starts the same way... something breaks and I can't seem to put it back together without trying to get more power out of the engine. What I have is an 11- 12 year old Murray Select 30" rear engine mower with a 12 hp Briggs & Stratton engine. I may not get into racing but the simplicity of this B & S engine appeals to me. I've tried to find go fast parts by googling Briggs & Stratton 12 hp model # 283707 but I honestly haven't been able to find the kind of parts I want. Is there nothing for my old B & S engine?