86 only. if it was 87 the carb manifold would be angled. main bearings/ gaskets/ seals same 86-87.
athena make complete gasket kit, will fit 86-88. main bearings same all kx500s.
the clutch actuator seal changed on later kx500s, not sure which year, but you can buy the seal kit from k&s for newer kx500, then just buy actuator seal from kawasaki. they still make it. all other seals same 86-04, even all the little power valve seals.
do you have the bike? what is up with the water outlet? this motor in another chassis?