Valve goes in and out of adjustment randomly

I am resurrecting a very neglected 1978 XS650. Gave a complete tune-up including valve adjustment, started it up, warmed it up on the road, and I had a loud ticking. Used a stethoscope to narrow it down to the LEFT INTAKE VALVE lash too big. The bike was already hot, so I set the gap really small and the noise went away. I did some more road testing, and I tightened the cam chain again, this time hot, enough to necessitate setting all of the valves again, which I did cold, of course. I noticed that the tip of the LEFT INTAKE VALVE adjuster looked hammered, like it had been too tight, so I put a new adjuster in.
Next day, more road testing, and all of a sudden I get a really loud ticking again. Didn't have the stethoscope with me, but I'm sure it was the LEFT INTAKE VALVE lash. Then a few miles later, it goes away again.
Anyone ever run into this? Valve lash on a single valve spontaneously goes in and out of adjustment? I always carefully feel for slop when I adjust valve lash, and it was normal. Otherwise, I would say gummy or sloppy rocker arm and shaft, but I don't feel abnormal slop. Could it be a gummy or sticking valve and valve guide? Try putting Sea Foam in the crankcase? Any ideas?

I agree with you on the pssiblity of something sticking. I might shhot plenty of your favorite penetrating fluid in around the valve stem. Both from in the valve adjuster end as well as the intake port end.
I was reading a references to a 50/50 mix of acetone and ATF or MMM was the best penetrant out there.
Leo

XSLeo said:

I was reading a references to a 50/50 mix of acetone and ATF or MMM was the best penetrant out there.
Leo

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I've been using "ACE-TF" for a few years now, it works better than Kearney's rust cutter, and just about anything else I've tried.

DB....hammered adjuster.... valve stem condition? could be pitted/chipped. When valve rotates (slightly) in guide and spring/retainer, it could possibly be increasing or decreasing clearance.

DogBunny said:

Valve lash on a single valve spontaneously goes in and out of adjustment?

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I think you're judging this by ear, and if you measured it you'd in fact see no change. Mine does similar kinds of things and I think the determining factor is how much of an oil cushion happens to be between the adjuster and the valve stem at a particular time.

I get more of it when I'm using a pitted adjuster. Screw them all the way out and look for pits. A real good replacement is Advance Auto Parts part no. 073 54016 306

Although it's not talked about much here, if I was riding around in 100F+ like you I'd consider an oil that's even heavier than 20w-50, like sae40. If I didn't want the racket.

I think the valve ticking coming and going is part of the charm of an XS650.......

You're not helping yourself by adjusting things on a hot motor, I would reset it all again cold and see what you get. My bike does the same thing, recheck them and ride.

Mine seems to clatter a bit more after I run it hard, like it's crying from the spanking I just gave it, lol.

NONclow said:

DB....hammered adjuster.... valve stem condition? could be pitted/chipped. When valve rotates (slightly) in guide and spring/retainer, it could possibly be increasing or decreasing clearance.

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I'll double-up with NONclow here. The valve adjusters actually strike the valve stems slightly off-center, purposely, to rotate the valve slightly. If the valve tip is sufficiently hammer/dimpled, clearances may change while riding. If it's hammer/dimpled enough, small flakes pop off the center of the tip, like brinelling, but has another name I can't remember...

Thanks for all of the responses.
xsleo, I will try shooting penetrants at the stem.

NONclow, not sure, but I suspect I'm the one who hammered the adjuster when I "re-set" it while hot. Good theory on the rotation.

xjwmx, I set the valves cold, then discovered the loud ticking on the left intake with a stethoscope, and then checked the gap. It was huge, hence no wonder the loud ticking. But, I had just set it cold an hour earlier. Hence the perplexity of the situation. One minute good, the next bad, then good again.
For me, it takes 2-1/2 quarts to get half way up the stick, I might try two quarts of 20W-50 and use straight 50 for the final half quart. I do something like that in my Sportster in the summer.

gggGary, ticking doesn't bother me unless it is loud and comes and goes, literally in the space of a few miles, that's just not right. I know it is way out of adjustment when it is loud, as I said I tested it when ticking and hot, the gap was huge.

hotdog, I would never normally adjust on a hot motor, and when I did that I didn't realize the full extent of my problem -- the gap was huge when hot, and I didn't expect it to suddenly shrink up again, which is when I think I hammered my adjuster.

5twins, clatter is okay, but this is a single valve going from quiet to way too loud.

TwoMany -- and NONclow -- I like the theory that the valve tip is no longer flat, but this is a pretty severe amount of lash change... although I guess it just needs few thousandths to go from quiet to loud. I wonder how long it takes for the valve to make a full rotation...

I'm going to try penetrating fluid on the valve stem, and some sea foam in the oil for the heck of it. We shall see, and I'll report back. The engine does seem to get better the more I ride it.

This is stretching the limits of the 'macro' feature of my smartphone camera, trying to get the lighting right to show the 'torroid groove' wear pattern on the valve stem tips.

1 - Normal 'torroid groove' wear pattern. (about .001" deep)
2 - A little deeper, with scratches or micro fleck. (about .002"deep)
3 - This was beat out of the head, but shows microcracks and a missing flake (stellite brittleness)

Valve rotation precedes me, but if I remember right, this was a way to prevent excessive face/seat leading (from tetra-ethyl lead) of the era. How fast do they rotate? Good question...

TwoMany, thanks for those pics. Here's mine. Picture is not the best, it was hard to take with the rocker arm in the way. The valve tip is absolutely hammered. I wish you all could see how much worse it actually looks in person. Way, way worse than TwoMany's third photo. Clearly a very uneven surface. I am declaring this mystery solved.

TwoManyXS1Bs said:

Valve rotation precedes me, but if I remember right, this was a way to prevent excessive face/seat leading (from tetra-ethyl lead) of the era. How fast do they rotate? Good question...

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Rotation enhances valve seat, reducing carbon buildup, and increases valve guide life. "Back in the day" (....Damn I feel old....) leaded fuel helped this. In the early 70's auto manufactures (Ford and GM that I know of) put rotators on ex valve springs when leaded fuel was fading from the scene. I've got a '61 Ford Unibody w/ a '56 292 V8, had to machine the old ones out and press in new hardened seats after I put 6-7000 miles on a "good" used motor, the ex valves hammered the seats so bad the stems were sticking up between 1/16" to 1/4"!!....I don't even want to get started on sodium filled valves

If you weren't planning to take the head off, I wonder if a few passes of small file could fix it. Would be worth trying - I think it could only improve it...

I thought of filing, but I assume that is/was a hardened surface and it would be difficult to do a good job, plus, I can envision the filings dropping down and getting stuck between the valve and the seat.
EDIT: On second thought, the valve guide would probably catch the filings first, still not a great situation.

Do they make valve caps for the ends?

I've heard of XS750/850 triples with shim over bucket design (between cam and bucket) spitting shims out at high revs, I think that would be an issue with "caps". Not to mention 2 more contact points.....not a good fix....

DB- I believe the filings would be insignificant, esp. compared to what the engine seems to generate on its own...

When you're finished get a greased q-tip and mop up the filings off the keeper and cap. I have a little file from HF that came in a set of files and would be perfect for it.

The valve stem tips are hardened (stellite), and this one has succumbed to spalling (that's the word I was trying to remember earlier). If the tip were to be redressed, it wouldn't last very long, unless it was rehardened. Long ago, I remember reading some books on metalurgy and heat treating, and one article talked about hardening and impact resistance, as used in rockers and valve tips, and the importance of impact cushioning additives in engine oils, particularily zinc based additives, which have been reduced in the last three decades. Other threads here discuss ZDDP, a zinc based additive, and it's importance in these engines. I would expect to hear more failures like this in the future. This is why I'm so interested in those elephant's foot valve adjusters. Just wondering if valves continue to rotate using them...

TwoManyXS1Bs said:

The valve stem tips are hardened (stellite), .... If the tip were to be redressed, it wouldn't last very long, unless it was rehardened.

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Stellite is an alloy that's hard to begin with and in fact resists hardening due to heat as one of its desirable properties. Don't make me look shit up. I don't have time for it. I'm calling bullshit this time though.

xjwmx, understood. Just trying to avoid writing a book here. Stellite is a hardfacing alloy that was applied thinly to many motorcycle valve tips and faces of that era. Used a Van Norman valve grinder in the shop, and we had an industry warning to avoid grinding more than a few thousandths to prevent loss of stellite. DogBunny's valve appears to have the type of damage that we would reject for regrinding. Might could reuse it if elephant's foot adjusters were used.

Here's an excerpt from the service manual showing the application of stellite.