For starting out I would suggest get a non ringed type instead. If the setting is too lean the engine will just quit. In a ringed engine, if the setting is too lean, the engine can keep on running tearing the rings apart and destroy itself! OS 50 SX, great engine but pricy and goes through lots of fuel. Super Tigre engines, can be very finicky to keep running and the carb barrel will eventually jam on most of them unless you remove it and machine it smooth. I would suggest an OS 46AX. Reasonable on fuel, easy to adjust to get it running great out of the box, tons of power and reliable. Its smooth running is nice to have in a trainer and the high power available makes it great for a 2nd or 3d type plane. Its a few dollars more than other engines of same size but the quailty shows right away when you start the engine.