I have a 63FZ, new from the box. Run twice with 90% 209/20 and the remained 10% composed of Omega in the last two days. Engine starts easy, runs slow but very nice but will only accelerate to abou 8,600 RPM - half throttle. It has a 12 X 8 prop on it. Gets pretty hot while running for a while. Touched the intake manifold and it was very hot (I would expect it be sort of cool as on other four strokes). First run HSN set at 3 turns out, tried 2.5 turns but still same problem of accelerating above mid range. I observe a lot of spit back going on in the carb throat. I observe that the card barrel/plate is only open about 15% to 20%. Runs steady at that speed. Ran three times very rich, then today second major run, ran for 11 minutes and stopped.

Running richer, e.g. 3 turns out, still will not run over 8,600.

Appears to me to be running lean, but three turns out on the HSN ought to be plenty but . . . .

What gives?

Chip