On the HW 5200 front, a side note. I put on a new carb from Langdon's. It has worked fine out of the box, sitting on the Redline adapter. While working on setting up my Cruise Control linkage, I took a look down the throat of the adapter. I feel reallly dumb. I can clearly see that the round hole of the adapter is at least 1/8" larger diameter than the hole in the log. While this isn't much in overall diameter, I would imagine it sets up turbulence, which I could have minimized by simply tapering the top of the hole in the log. That should have given me a smoother transition to the smaller diameter, and provide additional smooth flow.
I'm not brave enough to try my die grinder with the head on, and don't want to pull the head off again for now. Maybe next year. I think Ian will agree, that the same diameter hole will flow more, if the transition is smoothed by a tapered entrance.