Everything is interchangeable, to a point. To keep it simple*, keep heads, barrels, and pistons together.

For example:

• 1987 MC16 head/barrel/piston combination fits all years**
  
  
• 1988 MC18R head/barrel/piston combination fits all years
  1988 MC18SP head/barrel/piston combination fits all years
  
  
• 1989 MC18R head/barrel/piston combination fits all years
  1989 MC18SP head/barrel/piston combination fits all years
  
  
• 90~93 MC21R/SE/SP head/barrel/piston combination fits all years
  90~93 MC21SE/SP head/barrel/piston combination fits all years
  
  
• 94~97 MC21R head/barrel/piston combination fits all years
  94~97 MC21SE/SP head/barrel/piston combination fits all years

DO NOT mix the R/SE/SP heads/barrels/pistons.

*This is a basic compatibility, to keep things simple.
**MC16 parts will lower the performance of all other models, due to substantially smaller exhaust ports, and lower compression. The top coolant hose orientation on the MC16 is also slightly different to all other models. Conversely, fitting MC18/MC21/MC28 parts to an MC16 will increase its performance, but do not expect 60hp without plenty of additional work.
_________________
Andy.
NSR-WORLD.COM

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