'81 - '84 airheads had valve seat material that was too hard for it's own good.
Your exhaust valves are probably toast or on their way to being toasted. Your exhaust guides are probably shot, too. They're usually shot before 60k miles rolls around.
If you want to save some money, just have your guides and exhaust valves replaced and count on doing it again every 60k miles.
If you want to spend a wad, have your seats replaced too. If you're fortunate and it's done correctly, you won't have to worry about it again for a very long time.
Take heart, you're not alone: This is an historical and well documented issue with 1000cc airheads mfg'd between '81 and '84.