I've got a new H9 Showtime with a new Saito 125 on it. I broke it in fairly rich for about 50 minutes before I maidened the plane. We tached the engine at 9300 RPM before backing it down 300-400 RPM before flying it. The first flight the plane seemed to lean out and died. We restarted the engine, richened it up and the motor seemed to cavitate. I brought the plane in, richened it a little more and it seemed to have no power at all and would barely respond to throttle inputs. Here's the question. On the ground, the engine runs flawlessly. Is it possible that the cowl needs to be cut further? At present, the cowl has the stock intake holes, clearance holes for the valve covers and for the exhaust to exit. The general concensus at my club is there aren't enough outlet holes in the cowl and the air is compressing under the cowl. It makes perfect sense to me. Anybody have the same kind of experience? Thanks!

Dave