ORIGINAL: bigdanusa
The OS 120 AX is way too much engine for your 6 1/2 lb. Big Stick 60! Besides that it loves to suck up fuel fast!
You won't get much speed out of a 91 4-stroke engine unless you use a smaller prop and run it full bore which will only shorten the life of the engine.
A Super Tigre .90 would give you unlimited vertical but it won't stay tuned as well as an O.S. engine will.
If it was mine I'd have an O.S. 75 AX on it and fly it like a bat out of H???!
big dan
Too much power is just about right!
Only reason I would ever say to run a 120 two stroke on a 60 size stick is because the plane can handle the power and the pilot has control of the sticks. Down the road the 1.20 engine will give you a lot more choices on a bigger plane or one that needs to go on a diet. The OP is also a mile high so some added power could be a good thing. If it was my plane I have an OS .91FS and a SK .91 not doing anything at the moment, both great choices for any 60 size plane when you live high in the hills. A lot does depend on where you live and fly, at sea level the 1.20 would be way over kill, at a mile high???