IMO, the 50cc pumps were a waste of money. Don't fall in love with a number with the A/F meter. Make the plugs happy and then look at the A/F numbers.
I don't even have a A/F meter because I don't like trying to watch a gauge. IMO, you need to data log it, and plot it against MAP, RPM and throttle postition.
If you do all that, you can get the tune up down to a gnats behind. Just watching the gauge is a very inaccurate way to get A/F numbers.