Hi
Hope you can help please.

Is it correct that you can transfer all of the parts (excluding Crank) from an MC18 Engine to MC21 bare Crankcase?

Are there any issues regarding the Generator and Flywheel as I believe the fit of the MC21 Generator is slightly wider if you were to use it instead of the MC18 Generator with a MC18 Flywheel?

Many thanks
Phil

You need to be more specific. 88 R2/4J, or 89 R5/6K?

The 1988 has a larger flywheel than the 1989-1996 models, however the taper is the same on all cranks, so you "just" need the matching pulser coils, to get the spacing correct. (The harness will need modifying though, as the sub-harnesses are all varying lengths.) I'd say use the MC21 flywheel with the MC21 PGM-III and carbs. The MC18 porting is quite different to the MC21, but the ignition is very different.

Other than that, off the top of my head, yes, everything other than the crank is interchangeable. Be aware of compression differences between all models, so you should carefully measure deck heights and squish, just to be sure. Too low compression is just as bad as too high on the NSR. You want it bang on spec for best performance.

You will need matching parts like the primary drive gear/clutch driven gear, and external parts like the oil pumps will be different. But it's all quite do-able!
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Andy.
NSR-WORLD.COM

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Hi Andy

Many thanks for such a prompt reply very much appreciated.

Yes apologies I wasn't as specific as I should have been for the following reasons:

1) My son has put a MC21 Engine in his MC18 R5 (no Generator, Flywheel or Carbs) and was having a bit of trouble with the Generator and Flywheel, the MC18 generator was loose as the screws had bottomed out on the MC21 Crankcase and the Flywheel had been lost, however, now after a long search it has reappeared today (Bike been in total bits for 20+ years plus a move and I had promised to put this query on some time ago).

So I take it in the shorter term he could use all the MC18 R5 flywheel, generator and matching pulser coils and either shorten the Bolts or put some spacing under them as he just wants to get the Bike running initially and MOT'd? But afterwards source MC21 flywheel, generator, matching pulser coils, PGM-III Unit and carbs to get the required balance and performance.

2) For my own part I am planning a project to transfer the bits from my existing MC18 R2J to a set of MC21 Crankcases and MC21 Crankshaft & Conrods and was just going swap all the parts across.

Hence why I was so vague, so once again apologies I probably should have put this as 2 seperate questions.

Many thanks

Phil