I ran my OS91 FX for less than one tank on the ground, adjusted low and top end, and then it was ready to fly. What a great engine reliable, powerfull and very quiet[sm=thumbup.gif][sm=thumbup.gif][sm=thumbup.gif]. It is now turning a APC 12x14 @ 9000rpm on one of my sport "speed planes". I am pretty sure you are gonna like it.