I am still in the break in period with my new DA50 aboard a QQ Yak 54 80", so far about 1 gallon through it. Oil is mineral (Castro Super TT) with 1:32 mix, as recommended. Engine is mounted inverted in the plane, and muffler is pitts style. I fly at 700m (2100 feet) above sea level.

Engine starts fine, and transitions are ok too. High and low needles were untouched and remained at factory settings. The problem I experienced is that when flying it sputters continually. I thought that it was caused by the high needle being set too rich. Curiously, when flying inverted the engine sounded much better and very smoothly, with almost no sputter at all. I adjusted the high and low needles but no matter what I do the problem persists. I don't know what else to do, as the only variables that I can play with are these two needles.

Any helping hand on this? It will be greatly appreciated.

Thank you all in advance,

Fernando