I had a very cool 85, back in 88. Cab bearing surface in head went a way. Bought a engi g from a friend with. 480 lift, 280 duration cam, side draft carb, and super trap exhaust. Loads of fun.
the chain guides did wear out. No damage to cover... a piece of the guide got between chain and sprocket, skipped several teeth, and bent every valve in the head! Sad day.
Sorry no tech help,,, I've slept since then! But just one of my fun life stories!