Rudeboy

The Evolution 20GX is a 20cc small block gasoline engine designed for .90- to 1.20-size airplanes. It’s been designed with a standard beam mount and dimensions that allow it to fit anywhere you might use a .91- to 1.20-size glow engine. It’s also remarkably lightweight, even with the ignition system and battery. With the included 2S LiPo ready electronic ignition and crankcase pressurre type carburetor, easy starts and tuning are a breeze, allowing you to take the model to the air in no time.


I copy-pasted this from the Evolution Engines website...that's why I assumed they ran on crankcase pressure.