Possible success. I "went for broke" and drilled out the main jet. It swung the 20x8 prop at 6000-6100RPM with no sagging or surging and no choke. I want to run it some more to make sure the idle and mid-range are OK but it seems alright so far. My wife was yelling at me to come in so further tests will have wait for now. Not too bad, seeing as the RCS 45-50cc four-stroke advertises 6000RPM on a 20x10.

J