"DM" gave you good advice, not much to add to what he said. Any good quality 100 cc engine would be a good choice for this airplane. I have one ready to go as soon as I finish some mods to the engine box to accept a different engine that weighs in at 22 Lb minus engine, battery, and wing servos. I am putting a 3W106 in it which should be more than enough power for it. The new 3W106 is said to put out almost as much power as their 3W120.