As 2M said this morning, the XS650 engine castings are pretty low-tech by today’s standards. There are LOTS of voids and areas of poor metal integrity (flakey stuff) plus, I don’t think they were ever properly cleaned after the machining operations.

Thus, there is lots of swarf (metal debris) stuck inside - WAY more than any modern casting would likely have.

Fortunately, nearly everything that rotates inside an XS650 engine AND transmission runs in ball and roller bearings - which are very tolerant of tiny bits of debris and so, I really doubt that these little bits of stuff that you’re seeing in the oil will create any serious problems. About the only major exceptions are the tappets & rocker arms and the cam followers, plus of course, the piston rings & cylinder liners. However, all of those parts get pretty well lubricated by the oil pump and splash. Similarly, the 1960-70s two strokes nearly all ran roller/ball bearing cranks and the rest of the lubrication and cooling oil was carried in the fuel-oil mixture or looked after by the oil injection systems which worked pretty well...considering.

In contrast, the 1960s British 4-stroke bikes (Triumphs, BSAs, Nortons etc.) had mainly plain bearings as did the Hondas of the day. That type of bearing is very sensitive to debris in the oil, but most of the Honda’s generally had pretty decent oil pumps and filtration systems while the Brit-bikes....well, they were rebuilt fairly frequently.

Anyhow, I am not for a moment minimizing the importance of clean oil and of looking after the filters on the XS - but the basic design of these engines is really very robust and so I wouldn’t be too concerned for the level of use to which we are generally subjecting them these days.

Just my $0.02 ($0.027 CDN).
 
Yes, I'd do the same, just ride it. Maybe what you saw was just residue from the past, just now getting washed out. Honestly, I don't think I look that closely at my drained oil, lol. Maybe I should, lol.

+1. I just did a post in Mailman’s thread about precisely these points.

Pete
 
Yes, I'd do the same, just ride it. Maybe what you saw was just residue from the past, just now getting washed out. Honestly, I don't think I look that closely at my drained oil, lol. Maybe I should, lol.

+1. I just did a post in Mailman’s thread about precisely these points.

Pete
 
Ya, I was hoping it was the screws Jim, but I'll just keep a close eye and ear on things.

Thanks buddy.
 
My Briggs and scrap iron 18 horse zero turn had terrible looking "metal flake" oil when I changed it last August, swore the end was near. It's running strong, and I whale the snot out of the poor thing mowing lawn, and pasture fence lines..
 
...I think I'll button her up and check the oil again in another 100 miles or so unless you guys have any other suggestions as to something else to look for.

EDIT: All the wheel bearing grease that was packed in the needle bearing has been washed away and there was plenty of oil throughout the entire clutch assembly.

Yeah, no smoking gun. If it was the front guide, I'd expect to see a lot of black plastic, since the camchain has to saw thru that first before reaching aluminum.

Agree with everybody else and your plan. Run it, frequent oil changes for a while, monitor. Hopefully it's just residue, and the metalflake count should go down. Good to hear about the clutch oiling.

In the ol' shop daze, oil changes on good condition bikes didn't have metal flakes. If there were, would advise the customer that something's amiss...
 
We'll guys I appreciate all your positive encouragement yesterday but I can't stop thinking on this. 'Long post warning.'

Something was grinding away metal flakes and we all know I didn't fix anything so one of two things are going to happen.
Whatever was wearing is now worn so there'll be no more, or it's not and there will be.

This was my second oil change at 550 miles after rebuild and I didn't look at the oil on the first one. If I hadn't by chance put my drain tray on the one bench that's under a sunny window, I likely wouldn't have noticed all these metal flakes this time either.
I was hoping that this was just old material being washed out but you'd think it would have been done by the first 100 mile oil change so I'm thinking it was still occurring after the 100 mile mark.

Was doing a small job this morning for Terry, the machinist/vintage bike mechanic who did my machining work and ran this by him. Told him about the no joy on clutch screws and he immediately thought cam chain as well, but no chunks of rubber so can't be the front guide.

He hasn't seen this either but did mention that he remembered the old CB350 cam chains would slop around sideways in the tunnel.

I chewed on that thought for awhile while working and then wondered if it's possible that I could have installed the cam off centre enough that the cam chain or sprocket are rubbing in the tunnel. I looked at some pics and there's enough clearance there that I can't see how the chain could make contact with the side of the tunnel unless it had virtually no tension on it and I would think that would be pretty noisy.

But, is it even possible to have the cam itself off centred enough that the edge of the sprocket could make contact with the inside of the tunnel? If so this could be the flakey source.

I know I'm reaching here, but something had to be doing a lot of rubbing to create that much metal flake so I'm just throwing out my wacky ideas to see what you guys might think.

I also noticed that my tick is back, it has changed from a triple to a single tick but ittttt's baaaaack. Pardon my ripped shop shorts and t-shirt.
Don't let SWMBO know I posted this.


I tried some cam chain adjustments, slacker and tighter and that didn't seem to have any effect.

Then went for a 25 mile spin, mostly at highway speed. Upon returning home, the tick has lessened considerably but is still occasionally there.
Using a mechanics stethoscope again I can pick it up as far away as the front side filter screw but it is loudest through all the letters in YAMAHA. Possibly loudest at the middle A, but pretty hard to definitively say that. Wish I could put the stethoscope on my phone/camera.

Obviously I don't know but I wonder if I might have 2 different problems going on here. One tick on the bottom and one flakey one on the top.
What could I have messed up on this badly to cause these problems?

Anyways, at this point I have to most extremely, reluctantly, unwillingly, kicking and screaming, say if you guys think I have to pull this lump again I might as well get at it. At least it will be warm this time and should go quicker second time around. I'll try the lay on the top tube (with an old pillow) and lift with your arms method.

Looking at the top end again certainly isn't the end of the world, just a PITA at this point, but might I be splitting the cases as well?

I don't know what I'll be looking for and would sure hate to go through all this to end up still stumped.

I mentioned to Terry that I was going to run it for about 100 miles and then do another oil change.
He said, “Well, keep an eye on it and if there are more flakes you know what that means, and it will be obvious what the problem is”.
Maybe so for an experienced eye like his, but for me, don't know.

So, I don't know. I'm posting these thoughts to get feedback from you guys who have the experience in spite of the fact that I may not like what you have to say requires me to do. Whatever it takes, I just want this done, and done right.

Jeesh, maybe I should just put this plate, tank and tins on my 78 and ride it.
 
I'm on the fence on this one Robin. I guess mostly 'cause of my aviation background. Metallic oil is a definite "oh shit" moment in an airplane. And that makes me want to say tear it down. On the other hand, it doesn't look, sound, or "feel" like an imminent failure scenario. I'd still like to see the oil again after another few hundred miles.
 
I am no guru, but I suggest being patient, giving it a few hundred miles more as Jim suggested, and then re-check for the sparkly stuff decreasing in its presence.
After all, the sparkles aren't going to harm your engine.

Enjoy some evening rides and a Molson or two (after the ride, of course).
 
Ok Jim, thank you for your honest, experienced opinion. What surprises me is the fact that it really is running great compared to the way it was.and the clutch action is better than I have ever experienced. Weird!

I guess I'll carry on with my plan, run it for awhile, and then see what the oil looks like then. It certainly doesn't act or sound like its gonna blow up.

Thanks man.
 
The camshaft and its bearings have no choice but to be centered in the head if the cam end bearing holders are properly/fully seated. So, its sprocket shouldn't be touching anything. Haven't heard of any issues of camchain side-whipping. Closest thing like that would be on the XS1, where a stretched camchain can be shoved into the tunnel bridge of those early cylinders, like this:
XS1B-CylTunnel2.jpg

Camchain sawing on that bridge certainly produces flakes.

Your later XS650 cylinders don't have that bridge, an open tunnel, which allows the tensioner to shove the camchain quite a ways over, as in 5twins' pic:
XS650-ChainTunnel011.jpg

Listening to your "tick" sounds, there *is* a pattern.
You rev the engine up, clutch is accelerated CCW, nothing.
You release the throttle, engine braking, clutch is decelerating, nothing.
Just before the engine returns to idle - "TINK".

Weird.

On using the mechanics stethoscope, probing on covers can mislead you since they act like the skin of a drum. Try probing on the screwheads of the cover screws. Sounds travel better thru solid tie points, and web areas, like the area of the case that supports the bearings, about 1" inboard of the cover gasket.

Tracking mystery sounds can be maddening. You may get some ideas from this extraordinary long thread. Be warned, it is loooooong.

http://www.xs650.com/threads/high-pitched-mystery-sound.23162/
 
Just before the engine returns to idle - "TINK".
It will also occasionally make this noise when idling, which is how I first heard it. Revving it was just the method I discovered to reproduce the noise.

On using the mechanics stethoscope, probing on covers can mislead you since they act like the skin of a drum. Try probing on the screwheads of the cover screws. Sounds travel better thru solid tie points, and web areas, like the area of the case that supports the bearings, about 1" inboard of the cover gasket.

OK thanks 2M, I'll do that and see if I can better locate the source.
 
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