I only have one 4 stroke and many 2 strokes, and have yet to see a problem with the fourstroke.

-They take longer to break in than 2 strokes, your new one will most likely have poor compression. Over the break-in period you will see the compression come up as the ring and valves seat themselves.

-I broke mine in by running down a 14 oz tank, then shutting it off before it started sucking air. I did this for a total of around 6 tanks, mabye a little more. I could tell that my break in was for the most part done when I would notice no increase in compression after the tanks, meaning that everything had seated.

-After you do this, run it rich for a while while you fly it, for example if you tune it 300 shy of max rpm, tune it 1000 below max rpm for the first flight or 2.

-One mistake I made, get the idle tuned well before you fly. Make sure it is good and slow, I didn't touch my idle, and therefore had to have the engine running very fast to keep it going, making landings impossible(had to wait for deadstick.)

-Check the valve adjustments before you run it in and then after you are done with the break in. After that, just check them periodically (people say 10 hours, but no one has an engine hour meter, so I just go by every gallon)

Good luck
Alex