j911brick wrote:Really, all the parts between the 21-28 are about the same except things the frame, swingarm and electricle system. But if you want to change from mc21r forks to mc 28sp forks, then you will need the brakes as well. The clutchs should change from and R to SP with no problem, as long as you have all the parts.

Your questions should be more specific.

I thought my Question was specific enuff but maybe not? , firstly the question revolves around the engine! not the frame, swingarm, electrical system or Forks.
I know for a fact that the cylinders are not the same for a mc21 and mc28. I also know that the cylinders from a MC2x R engine not the same as a SE/SP engine. what id really like to figure out is what parts are not interchangeable between the mc21 R and SE/SP and the mc28 R and SE/SP.

Thanks,
Markus