I have an odd problem on my R100GS. This is actually an R80 top end BTW. The right side exhaust valve rocker keeps getting tight vertically. The heads, valves, and cylinders are all in good shape. The problem was noticed by a mechanic recently when we did rings. It was tight, almost no vertical play, when we took it apart, but we both assumed that when everything was put back together right, by someone that knew what they were doing, the rocker would retain the vertical play that we gave it. But within a few hundred miles, doing the first re-torque, it was tight again. I have loosened it repeatedly, and it always gets tight again. Nothing else is out of order. The studs are fine, holding torque, and the valves are not changing adjustment.
Here's the situation. The one rocker only tightens to the point that when you go to set the valves, there is almost no perceptible vertical movement. There is no "click", but I can see it move, and it does move enough to pinch the oil film. There is always a pool of oil in both sides of the rocker cover, and the rocker itself is clearly getting oil. When the valve adjuster bolt is loosened, the rocker pivots freely, you just can't keep the right amount of vertical play in it. It seems to go back to the same level of tightness and then stay there.
Has anyone ever had this problem before?