Hi,
What kind of oil were you using? Where you using the NGK plug that came with the engine? Some oils form lose ash in the cylinder and piston crown. Lawnboy ashless is good for breakin. I don't know what oil Scott uses, only that he uses a low percentage of oil because of close tolerances. I think that the long intake on the trimmer is to isolate it from the heat of the cylinder. I don't think that it caused the ash buildup. It could be augued that the thicker insulator provides more time for the mixture to atomize for greater power. How was the RPM and what prop?

Dave