On my 4th one now...couple of dumb thumbs and a leaky fuel tank...the YS 63 would be just a little on the short side...I've got that on my MoJo 40, now that's a great combo...this last 46 ucando I went with a Satio 91, the first 3 had the recommended OS 70...not a bad combination, but the plane really has come alive with the Satio 91...Jumps out of a hover and out of trouble if it rears it's ugly head,... if you check you'll see there isn't any weight difference between the two engines to speak of....in fact on my postal scales the Satio weighed in just less than the OS...ran a 14x4w on the 70 and am running a 15x4w on the 91..15%
Above someone mentioned bad tendencies...the only one I can find fault with is it doesn't harrier very well without alot of wing rock...one has to be on top of it all the time...trying an experiment tomorrow on that...installing some 1/8" dowels 4" long 3" back from the leading edge at the wing tips .... top an bottom...seen sail plane pilots do this....keeps the tips from stalling before the wing root stalls...so they say...will find out...set your cg at 5" back from the leading edge for your first few flights and then slowly move it back until you reach your limit...but don't go beyond 6"..I'm at 6" now and it's just a tad tail heavy...takes a little down elevator to land...just wants to keep floating along nose up...with about a 5-7mph head wind it will just kinda stand still...little more wind and it will even back up...you'll love it....a very easy forgiving plane to land...good luck with it...