OK, after reading all the advice (thanks to all by the way) I followed the traditional method of keeping a safe distance and opening the power full throttle to set main needle and idle needle by listening to engine at idle. Good results were achieved. I decided to abandon all fear of opening the throttle fully and it actually wasn't that bad.

1705493, I'm running a Century Hawk with a MDS 38 which, contrary to everything I have ever heard about MDS, has not given me any hassles at all. It starts fairly easily, seems quite powerful to me and never cut out etc.