Tim is correct and a big help on my enya engine woes. I just saw a Enya 40 ss throw a rod on it's 6th flight just last sunday. It just went (pop) I have a couple of these little guys around, and they do real well, and have good power. I hope they do last for eternity, as they run very nice for a 40 size engine. Good luck on break in. I saw what happens first hand. Be patient, I had never seen that in over twenty years of this hobby..............Dave