Dick,

Have you checked the balance? The OS 91FX weighs about 24 oz. with muffler, so I'm sure your FSR is close to the same. My Irvine 53 weighs 18 ounces with muffler. That's 6 ounces lighter, and it will make any airplane fly differently. Other than that, I'd have to know what you meant by "steady".

For break in, I just ran about 10 flights of SIG 10%. It's an ABC engine, so if you run it too rich it will take forever to come in. But don't lean it out and then fly it! When you hold it with the nose straight up it should just break into a steady 2-cycle, but not fully lean. And stay away from long vertical lines until later. I like to fly large loops during break in. This works the motor on the climb and cools it on the dive. Be patient. You should be okay with the 12x6. I like the APC 12.5x6. For 3D you can use any of the popular funfly props...APC12.25x3.75, 11.5x4, 12x4, etc.

Chuck