Camshaft End-play

I've got a 1982 Seca 750 and I have noticed a tapping noise from the right side of the engine when it is warm. After some researching I found a place that said it is probably safe to ignore and that there are some loose tolerances for the camshaft end-play. Is there a way to tighten the tolerances? Or is it just how it is. Just trying to get some piece of mind as it worries my in the back of my head. I haven't noticed the sound getting any worse over time in fact it is almost exactly the same as it has always been jsut figured I would ask.

 

Have you checked the valve clearances, that might be causing the sound. I read years ago the Suzuki GS 1000 made a noise at idle because of camshaft end play but it dissappeared when the throttle was blipped, not heard of it on an XJ before now.

 

Yes I have done all the valve clearances and still have the noise. I'll see if I can find the article page

 

A "tap-tap-tap" in the upper end may or may not be something to worry about; if it’s s “sharp” metallic sound…..that could be a cam bearing or cam cap problem. Both the XJ650 and air-cooled XJ750 engines had a factory TSB (Technical Service Bulletin, or in other words, an internal "warning" to their dealers) regarding slightly loose tolerances for camshaft end-play on these engines. It's a regular ticking sound that increases along with the engine speed, and is most easily heard from the right side of the head when the engine is hot. Generally, it is safe to ignore it, as no harm is being done. The camshaft end-play is not so large as to cause any damage.

If it’s just a soft, sewing-machine like tick-tick-tick sounds, then that is probably just the valves happily clicking away through their proper clearances. By the way, the lack of this tick-tick-tick sounds is not a good thing: tight valves make no sound, and tight valves are a quick way to ruin your engine!

this is the paragraph from this article. The Information Overload Hour | XJBikes - Yamaha XJ Motorcycle Forum

 

Most likely a loose header pipe at the head

 

On one of my bikes the cam tunnels have been ravaged and it sounds absolutely awful.
I could feel the play when I assembled the engine .
Bike runs damn good though.
Not really fixable from my research, although Im keeping my eye out for a complete 2nd hand head, just in case.

 

Do you mean the journals?

 

You can "refit" the cam caps to an extent, but you have to be clever about it - it needs metal removing from the mating face, very carefully, and then scraping metal away from the journal surface to create the new "bearing".
Hard to do, easy to mess up...

 

How do you know when the clearance is right?

 

Plastigage.

 

Yes same stuff they use on crank bearing clearances, cheers.

 

Yes journals. Used plastigage and had a least one cap not even able to compress it. Looked like someone ran it without oil for a long time.
Got to that point after refurbing the whole engine, so I assembled anyway. Not happy but amazing how it runs so well.

 

That's unfortunate, hope it keeps running well.

 

Well yes you can, but I just do it by feel, and then use a dti on the cam, (dry), lifting it up and down to indicate clearance. I've used valve lapping paste and a belt to turn the cam before now to get the bottoms all aligned. (obviously use a scrap or spare cam). It's not rocket science, just fitting - but head off valves out job.
My 750 "spare" (might actually be scrap) engine has dreadful score marks under the bearings, cam as well. If it's worth keeping I would spend some time on the bases and caps, replace the cams and rebuild, but unlikely since I have more than I need.
(Running without oil, or more likely with old oil and blocked or bypassed filter is more likely the culprit).

 

You know your stuff Minimutly cheers.