Hello stranger! :)
Sorry to hear the MC18 is sick... let's see if we can give you some pointers.
First thing first, pull the plugs out and drop the expansion chambers off. Inspection through either the plug holes or exhaust ports, or even looking at a plug itself could indicate if it's the top-end or the bottom-end that's died. If you managed to start the motor, but it wouldn't idle, it would suggest a bottom-end problem.
I seem to remember you blanked the power jets, but it's a long time ago that we discussed it, so refresh my memory please. I'd pull the carbs off anyway, and check for a blocked jet, just in case.
There, that'll keep you going for an hour!
Andy.
NSR-WORLD.COM