thanks again Andy. I agree with your approach. The set of carbs i have are marked 21ABDF. I don't see that number anywhere on the chart. Can't see any TA before the 21. does this make any sense?

Also, when you said "flywheel" are we talking about the alternator rotor/magnet? if so, how can i identify the MC18 MKII version? Pictures on the auction site don't show much. Is there an identifying number or mark?