I have an NSR250R mc16 that i have been using to race. After being beaten by another nsr, figured it was down on some horse power. Anyway we pulled it apart to find a bit missing off the top of the piston which had bounced around the barrel for some time.

So what's the best thing to do-

1. have the barrel repaired and buy new pistons or
2. do the barrels off the mc18 fit the mc16? If so what other parts should i change?