Adam, save yourself the hassle, and find an MC18/21/28 bottom-end... and also save a set of 24 year old crank cases from a butchering!
The MC16 cases aren't very good internally anyway, and need a lot of work to get them flowing as well as the later models, although it can be done easily enough. Also, the barrels have much smaller exhaust ports and the motor as a whole will never give you much over 45hp in standard form, if it's in good condition and well optimised. It won't do the MC18 chassis any justice.
What exactly are you struggling with for your MC18? Is it a Mk1 or a Mk2?
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Andy.
NSR-WORLD.COM
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