The 85's were part of the short stroke era or 'power years' (84-86). When running properly they are a rocket.
Pro's:
-Most powerful year of CR500 out of the box.
-Many engine parts are shared/adapted from later years. Upgrading to modern digital ignition is easy..
-Ergo's and handling are good for an 80's bike. With a little help (wider pegs, suspension work, bar position etc) they can feel/ride much like the later CR500's.. Which isn't all that outstanding compared to new bikes lol
-Lots of options for suspension improvement. After updating my 84 trust me--it's more than worth it.
-Aftermarket plastics, tanks, exhausts, seat covers and such are readily available.
Con's
-Dated suspension.
-Magnesium water pump housing is famous for rotting out and leaking coolant into transmission. I 'think' the later aluminum case will swap on but not positive.
-High pipe likes to burn through riding gear
-drum brake rear. Performance is actually pretty good however the aluminum torque arm is a rock anchor and bends easily.
-Rear linkage uses a bushing for the lower arm. If it's not shot or seized by now it is highly recommended to pull all the linkage apart and grease thoroughly.
As far as dirtbikes go you can't beat a big bore 2T in the sand--too much fun