Ive had quite a few YS engines too, always ran flawless for me until my Dad got the 110. It would dead stick on him until finally the firewall broke off the plane last dead stick landing. He had even sent it in to YS and received it back claiming perfectly fine. I took it over from him, fixed the plane and went on with it.. ran great for about 5 tanks, and started running erratic and dead sticking again.. I found that the gaskets were getting eaten up somehow, no matter what I did. they are nearly just paper as it is.. I rebuilt it 3 times with new gaskets, same scenario.. about 5 tanks and problems started with gaskets leaking being eaten away.
I still have it in pieces, but unless I find a better quality gasket set.. it will remain in pieces.. its too bad for that one, because I have always had flawless running YS motors otherwise. Maybe just something out of play with that one causing extra vibes that eat the gaskets.. I dont know.