V. Recession

[Air4Life]

http://bmwmotorcycletech.info/valves.htm


I only had my cell phone picture to share.  I am thinking its time to ease off the highway use and prepare for a seat and valve change.

[Bob_Roller]

As I've mentioned before, my '81 R65 had severe recession .

45,000 miles and the valve head had metal that had 'flowed' towards the valve stem on the exhaust port side of the valve, looked like a sloppy weld joint .

The valve face was worn to the point that you couldn't see the three angles that were originally ground into it .

It's a bit costly, but having a valve break and destroy the engine is a lot costlier .

Have you made any decision on where you will send the heads for refurbishment ?

While you are having the valves and seats replaced, have the shop check the cylinder head to rocker box surface for warping, not uncommon to have some warping there, may save you a oil leakage problem down the road .

[Air4Life]

Have you made any decision on where you will send the heads for refurbishment ?

I think Tom Cutter is nearest to me.  I guess I will ask him first to see if he is interested in the work.

[Air4Life]

I don't know why I'm having a problem comprehending this...   S. Bum writes, " ...and you do NOT let the valves get, APPROXIMATELY, half of the normal setting or less.."  I take that to mean, that since I normally set to .009 for the exhaust, that half that gap would be a closing up to 0.0045 would be a bad sign. Yes, I would think so too.  If that is the case, that seems pretty drastic.   Can you clarify what he means here?  

I'm not detecting closure rates anything like that.

Improved pictures attached.  

[Barry]

I tracked down the Snowbum quote but couldn't make much sense of it in terms of an indicator that you need a valve job. I think he was just saying adjust the clearances often enough that they don't close up by half the setting so as not to shorten the time the valve spends on the seat transferring heat. I agree though that it would be a bad situation to lose half the clearance between service checks.

 
I thought a better indicator when a valve job is needed was this ..

"If you find the valves closing up several thousandths of an inch every 1000 miles or so, you are in a trouble area...."


If it's any use as a benchmark my exhaust valve clearances close up by no more than half a thou in 2000 miles.

[Air4Life]

Thanks Barry.  Sorry, for making you search it out.  I should have included the entire paragraph from the above link.

I tend to over think when I'm trying to decide how to approach the semi-unknown; as a result I ask tiresome questions.  Thanks for your patience.

After a closer inspection of the valve angles, and based on my last valve lash check, I am not seeing enough to warrant a move to rework it just yet.  I hope to have the pulse air system removed by the end of the weekend.  I have decided not to exceed 65 mph as well.  If I thought aviation gas would help I would mix some in from time to time too.  Though based on his advice I don't think it would help...