hi fella, my 86 (same shape, frame etc) wore an 88-04 fmf pipe just fine, as long as u use a little imagination with the mounts, no cutting or altering of pipe required....
also, pro circuit make a pipe for the 86 which bar powervalves porting and rear brake is identical, dont know if they make one for 85 but if they do it will be part number pk85500p. the 86 part number is pk86500p.this is a mid/top end pipe.the 88 on fmf pipe i had was a low end pipe, part number 020055.hope this helps.