The 86 has an analogue ignition system with a cam sensor, the 87 has a digital ignition system without a cam sensor, the 88-89 is different again with difference advance settings...Maybe. The HBoL says FG-FJ 15-37deg BTDC with the FK being 12-35 BTDC. Except the 88 'FJ' had two ECU's, the later one was identical to the 89 'FK'. I think the HBoL is wrong here in that the early FJ was the same as the FG-FH but the later one was the same as the FK. The 86 drives the tacho off the ECU (same wire also triggers the fuel pump relay) while the 87 drives the tacho off the #1 ignition coil (and triggers the fuel pump relay off the #3 coil.) The 88-89 then goes back to a (dedicated) wire from the ECU for the tacho with the fuel relay now off coil #4. Not to mention also that the 86 cams themselves are different from the 87 both in carrying the aforementioned cam sensor pickup but also being "sprung". In addition to all that the pulse generator and pickups are all different between the 86 and 87 and then the starter, idler and pulse generator again are different to the 88/89. Also the crankcase covers differ, there are 3 different right types and two left. The alternator swaps direction between the early and later bikes and the crank, flywheel etc all change to match.