Just picked up what I thought was a kx85. From the frame Vin it is a 02 kx85. In process of freshing up motor come to find out the motor is out of a kx80(motor Vin says kx80 rather than kx85. Also the piston measures approx 48mm instead of 48.5) I narrowed it down to its either 86-87 or 88-90 do to the head design. That'sas far as iI can get without some help. So what I need to know is how can I tell 86-87 motor from a 88-90? The heads appear to be the same. I've googled for hours with no luck. Plz help!!!!! Thx