Ok, I think I got it, I read the article which explains clearly how it works..... so, what I understand is that the 2 strokes should be use for basic flying and the 4 strokes for sport flying?????? because it has better performance?????

I have a question, I think I am gonna get a cessna... it says it requires either an engine 2c .40-.45 or a 4c .60 Can I use a 2c .46 engine to fly it?????? or it's too big?????? I would prefer this because I want to train with this basic plane, just basic flying...... and then... when I feel ready or more skilled... I think I can get another plane and set up a 4c which will have better performance...... am I thinking right??????