Valve Seat Recession

[rwait]

For those of you wondering what it means when someone talks of valve seat recession, below is a picture of what it looks like.  The exhaust valve on the left is receding into the head...it should be flush with the valve seat which is the outer ring around the valve.  

My R65 is a 1979 model.  Fortunately I picked up a parts bike awhile back that only had 10,000 miles on it.  The bottom end had been damaged but the heads were good.  Just swapped them both out yesterday...really a relatively easy job.  I need to readjust the carbs now but am glad to have the, relatively, new heads on.

Symptoms that led me to think this may be an issue included the need for more frequent valve adjustments (say every 1,000 miles or so), and the fact that the exhaust valves were nearly at the end of their ability to be adjusted.  In fact, the last time I tried to do an adjustment, the right one had no more adjustment on it!

Randy

[tvrla]

No doubt about it - that valve is RECESSED!!!  

Are the 'new' heads from a pre-1981 or newer? Same size valves?

[rwait]

The 'new' heads are from a 1979 model....same year as mine.  I suppose they will experience the same thing after several more thousands of miles (original had at least 75k miles on them), but by then I'll probably have my old/original heads rebuilt.  

[montmil]

That's nasty looking, Randy. That said, it's probably repairable with a new guide, valve and seat work plus a little love.

You are fortunate that the valve and parts of the seat did not detach and destroy the piston and cylinder... as is often the case. In spite of the valve and seat damage, I'd call you lucky. Kinda.

[rwait]

Thanks Monte.  So glad I didn't encounter the other damage you mention....I wanted to keep riding but once there was no adjustment, I took it as a sign that now was the time to replace the heads.  Glad I did!