RE: Multi Engine Break In
#1, choose your motors wisely. I installed my new OS .91s in my Bronco, ran 4 tanks through them and adjusted them a little rich. When the motors had a good idle, transition, and steady RPM at full throttle, they were ready to fly. I used the same technique with a couple of new OS .25FX motors. The time on the ground helped me get familiar with each motor.