Was running the XT carb which has a rather large venturi. Blow down could be it, personally I think its the piston characteristics. I think compression needs to be above 170 to make a 372 with a 268 piston strong. I never run short bars on my saws when i test them because the guys who buy them don't run short bars. Buried with a 28" bar in fresh fir wasnt some thing it liked. The Jred I posted I wouldn't say went through a true test. The two of these I've built with compression above 180 were both all around strong saws. That jred sure does scream more but I'd like to see how it does with a 28" in some harder wood. In another thread trappermike advised me not to raise the transfers on the lazy jug. Just thinking out loud here. Thanks for the input.