'77 R100S Roughly 80,000 miles, recent 10K service by PO Feb.'12, no comment by service folks about valve seat recession.
While doing pushrod seals I noticed left side exhaust adjusting screw is nearly backed all the way out, about .250" higher than any others. Also the left side is 120# while the right is 130#.
Rechecked adjustment after less than 1,000 mi. and exhaust in question was at least .003" closed up.
The big question: I'm sure I'll tear it down this Winter to see what's actually happening but should I or could I run it for another month or so?
Bike is running very good getting up to 54 mpg. Hate to jeopardize some very expensive components!
My thoughts are that if it closes up the full .008" it shouldn't drop the valve as it will held in place by the rocker and pushrod. Naturely I'll experience loss of compression, etc.