If this is for your first plane its easier to hear what is happening on 2 strokes because of the noise difference. 4 strokes don't sound much different between slow idle and full rpm so its difficult to adjust the carb properly without a tach. 2 strokes also have a much shorter break in period which means you can get flying sooner. 2 strokes are considered flyable after 3 or 4 tanks of fuel have been burned. With 4 strokes I have read where some consider that you are supposed to burn a gallon of fuel through a 4 stroke engine before you even mount it on the plane! Thats a lot of fuel and running time with out air time. Nuff said![8D]