Valve recession is/was a problem starting with the '81 model year bikes .
I think by '83 or so they got it figured out, that the new material of the valve seats acted like an insulator not allowing the valve to transfer heat to the seat and then to the cylinder head .
I had 45,000 miles on my '81 R65 and at best had 5,000 miles before the exhaust valves would have been pulled past the seat and probably have the valve head broken off .
The official BMW term for the anomaly was, valve face plastic deformation .
Welcome to the forum, enjoy the 'chaos' !!!!