Old Fart- the biggest thing I've learned about tuning engines is that you have to take off and fly around the traffic pattern a few times and listen closely to the engine. It isn't really tuned until you do that. About half the time I have to land and richen the low speed need of a Saito just a tiny bit. But, if you do that and land every time you hear the engine sag, stumble, or run erratically the least little bit you will richen it to the just right point and that Saito will be the sweetest running engine you ever saw. I do the same on 2 strokes. Everybody forgets how important the low speed is on those engines too.