On mine it initially overheated - dropped down to 5 percent fuel - it would kick back hard when hand starting so I put in a second head gasket and it is much better. The large volume Pitts muffler comes with reducers in the exhaust tubes which helped with fuel flow as well. Using 13x8 and 14x6 apc props for sport flying. If you dont like the remote needle valve the Magnum 91 xls carb can be used on it. Also using an OS8 plug. Mine is a strong and reliable engine.