I had a similar problem 89 r100 gs. Had oil blowing out breather bike leaking oil from air cleaner area.
Removed right side valve started engine had a puff of compressed air on each cylinder compression stroke.
My mechanic looked at bike said I had worn valve guides excessively worn.
When pulled apart the piston were black with burned oil - rings were bad.
Total rebuild done on cylinders. New rings,connecting rod bearings,new valves,valve guides, all done.
Runs great now cost mucho dinero. 50k miles on bike at this time.
But give some more info on year of your bike and current miles.
Airheads do have some known problems for certain years.
Looked at your profile saw was a r60/6 1975. What is the mileage ??