1st thing I look for before buying anything is does it have a title, and soes the VIN # match the chassis
2nd thing I look for is did the previous owner put a friggin twist throttle on it
next I look to see what aftermarket parts are on it
then I look for rust
last I look for the previous owners knowledge (has it been bored to 350cc)
If you want a easy machine to ride, go with a 85/86. If you want the rarest, get a 87, if you want the best machine for modern upgrades get a 91-92