All the posts about seizure has got me thinking. As I intend to keep my NSR for years and ride it lots, I am going to start building up sufficient spares for a full engine rebuild.

For my MC21 model - R8N, the parts list shows 3 barrel sizes, A, B & C. I have read the technical section (thanks Fontyyy!) but can't find an explanation as to why three sizes exist for the one model engine.

Could anybody explain the reason, and what are the actual differences between the 3 types?

Also, does this mean there are 3 types of piston sizes? Jap4 & tyga just list a single 'top end rebuild kit', with no mention of specific barrel types. The parts manual lists Piston, Piston B, Piston D
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30