ive been researching which later model parts fit the 86 for about 3 yrs now.86 -89 ignitions are the same.you can use a later setup but you have to use all the components, cdi, stator and f'wheel.as for pistons, the later 2 ring works fine, with just a slight drop in compression as it isnt domed like 86 piston.if you ever need an exhaust you can run fmf from later models if you use your imagination when mounting it, but they fit and run well.i am thinking on the clutch side it might be possible to transplant the 87on clutch as a whole to alleviate the scarcety of parts.the 86 clutch runs a 5 spring/bolt arrangement and the later ones are 6.HTH.