i am unsure of dimensions off top of head but my 86 rotor is about half the weight of my 94. it looks like it is 30 percent smaller, maybe morei remember looking into it a little, it seems they went to big flywheel in mid 89. i bought an early 89 setup for my 94, it seemed to help alot, made the bike rev easier, felt lighter in the tight stuff. i noticed the same going to lighter rotors on my crs. i am unsure on igniton mapping for the years.