Prophex,

I agree leave it in the plane and break it in. I have done quite a few of the OS46AX engines and had done everyone of them exactly like the manual calls for and have never had even a small problem.

You really only need to breakin on one tank, doing two tanks won't hurt. If you do one tank on the ground, fly the next tank with the engine running a little rich but avoid prolonged nose high flight like vertical climbs and extended full throttle runs. After the second tank that you fly with, then start to lean it out for max rpm minus 200 to 300 rpm rich of peak rpm.