I had just asked the same question about a week ago or so, kind off. I was asking about the four strokes since I have all two strokes and I have heard about how hard they are to tune and keep running. I was asking about the four stroke for a 4* 60.

I did buy a O.S.91 four stroke and put on my 4*, the only reason I went with O.S. is because all my two strokes are O.S. and they all run great so I wanted to stay with O.S. So I am not saying O.S. is the only way to go, but I am very happy I did.

I did the break in just like O.S. says to do with out one problem. After break in I started to fly it and I only have 10 flights on this four storke, since I just got it ready to fly last Sunday, but so far it runs perfect and it sounds great.

I would say go with a four stroke you like and you will love it and they are not really any harder to run than your two strokes. If you have not heard this before, you will, and that is once you run your first four stroke you will be buying more. I have heard that and I am buying more, they are worth the extra money.