Hi guys, i am working on a bike a friend bought. it's a 1988 nsr 250r. it has a stuck piston. i got it apart and am going to order new pistons and have the cylinders re coated. i have been reading that this bike can take one of 3 different pistons. a-D. B or C. i do not know what piston this bike takes. i have been trying to do a vin search but i can't find any info. the first of the vin says MC 18- can someone help steer me in the right direction.. Thanks.. Phil