All NSR barrels are interchangeable, however the port timing differs between each generation (MC21 and MC28 are the same). But more importantly, you must ensure the RC Valve operation is correct. It's not as simple as just swapping barrels as the range of [valve] motion differs model-on-model.
It can all be made to work, but you need to be extremely careful with final setup.
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Andy.
NSR-WORLD.COM
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