With the YS120 you'll need the servos in the tail. Double pull pull is lighter, but you'll end up with lead in the tail.
I went with 2.75° right on the Saito 125. Spot-on.
The YS120 should be a Little more tan 3°, but 4° seems much. 3.25-3.5 should do the trick????
Some pics of the build:
https://www.facebook.com/media/set/?...1&l=f5293bdc8d
I set up the throws for same up/down movemente in ailerons. Ended using 73% differential in the radio after trimming.
Fiberglass is
http://www.fiberglassspecialtiesinc.com the regular "pointed" one. 45°degrees down engine fits very well.
Gear I think was from
http://www.tntlandinggear.com/
Spinner of course Tru-Turn "Ultimate" model!!!!
Fot the gear I used just a flat 1/4 ply plate epoxied in place of the kit mount. No reinforcements!
3 holes with 1/4 nylon bolts. Had to trim the aluminium mount a Little to get the wing to fit. No problems until now!
But, the Saito has had flawless operation, 0.0 dead sticks and no out-landings so far. I don't think it will hold up a very rough landing.
Build to fly, not to crash - It is an aerobatic machine, not a ground attack aircraft!!!!
Anyway if it "rips out" it works like a fuse, damage on the lower wing with the wheel pants is a chance.
Alumium plate is very rigid, I think I would go with a thinner gauge...