I have no experience with 4-strokes but I did set it up and tune it per the instructions. It idles pretty good, goes from idle to full just fine on the bench. When I take off and fly around it makes a slight knocking noise at 1/2-full throttle. When I went I went into sustained vertical the engine would die. What's the deal? Is the high end to lean?

One side note: the Showtime has great glide characteristics! I did 3 deadstick landings today with no problems on it's maiden flights!