Another "diagnose my mystery noise" post.....

[peanut]

That is a great idea Peanut, I'll put some 20W50 oil in it and take it easy for the next few months, then do the top end over winter, it has done 20K miles so I am under no illusion about it needing a new cam-chain/guide, and the valves are black and crusty. I tried running Forte engine cleaner through it but it hasn't helped.

if its any consolation the noise in my engine is far worse and I've been thrashing mine around for months .
I will have to strip mine this Winter to see what is going on but I think it will give me a few more 10 mile rides as its not getting any worse.

In the meantime I find if I just shift my head a little to the right the noise goes away ......

 

[highboy_coupe]

Although it is now quiet when cold, I noticed on a few runs it is still pretty loud when it gets hot.
Whilst I am fully aware that I will be removing the engine over winter, in the meantime it doesn't hurt to search for clues. I found this video that sounds exactly like my hot engine sound, and make the same noise when revving too.
So, my question is, is his he explains that he accidentally set the valve lash on the exhaust stroke? I thought both rockers were only free to move on the compression stroke? When he set the valve lash on the compression stroke it quietened down.

I set mine by going for TDC and then checking which cylinder has both rockers able to be jiggled; but the noise similarity is hard to ignore, that pinging metallic rattle and loose rising rattle sound on revving (when hot)

 

[peanut]

I set mine by going for TDC and then checking which cylinder has both rockers able to be jiggled; but the noise similarity is hard to ignore, that pinging metallic rattle and loose rising rattle sound on revving (when hot)

Forget all that crap about valves rocking etc thats for folk that like making things difficult for themselves.
.(...its all too easy to get it wrong that way .)

The easiest way to get your valve setting correct is to adjust the exhaust and inlet valves on the left hand cylinder when its piston is coming up to TDC on its compression stroke .

TIP....remove the plugs and put your finger over the spark plug hole and you'll feel the compression building up in each cylinder.

Then turn the engine over 360 degrees until the piston in the right hand cylinder is rising to TDC on its compression stroke and adjust the exhaust and inlet valves on the right hand cylinder

 

[highboy_coupe]

The easiest way to get your valve setting correct is to adjust the exhaust and inlet valves on the left hand cylinder when its piston is coming up to TDC on its compression stroke .

Thanks, that's what I thought, on the exhaust stroke at TDC the exhaust valve has to be open, right? So not adjustable?
I was trying to work out if I could have messed it up last time, I don't think I could have because I managed to get .003 and .006 measured on the same stroke, so both intake and exhaust where definitely closed.

 

[peanut]

have a read of this I think you will find it very interesting.
Howard is a qualified Engineer and something of an XS650 expert . He has done some exhaustive testing on this engine .Most folk in the UK gets their engines built by Howard
http://www.smedspeed.co.uk/tech.html
This is what he says about the valve settings

'The late XS650 cams set at .002" intake tappet setting is ridiculous. I can’t think of another OHC engine with valves this size that has such small clearances, the camshaft has a run-out of over 0.002 in many cases and setting the tappets to this small clearance will allow the valve to stay open perpetually. It is an effort by Yamaha to reduce engine noise, but this is not the way to do it.
I set all the tappet clearance at the early settings of 0.006 and 0.012. It allows in more oil, and allows for a generous growth in the metal parts, remember….. A loose tappet is a happy tappet.'

 

[5twins]

If your valves are set correctly, there will be no play in the rockers on the cylinder that is on TDC of it's exhaust stroke, only on the other one that is at TDC on it's compression stroke. But, if the valves were set wrong, on the wrong stroke, there would be play. At TDC on the exhaust stroke, the exhaust valve is almost closed and the intake is just beginning to open. It is possible to open them both up enough to set them there but it's not the correct place to be setting them. They will end up way too loose at the right spot, TDC on that cylinder's compression stroke.

I guess you'll need to check your work. Pull all 4 valve covers and set the motor at TDC. The rockers on one cylinder should have play, the ones on the other should not.

To determine which cylinder is on TDC of it's compression stroke and can have it's valves set, I slowly rotate the engine by hand using a wrench on the rotor nut and watch the valve action on the left cylinder. I watch for the intake valve to open and close, then the exhaust valve, then I keep going until the intake opens and closes again. I now know that cylinder is approaching TDC on it's compression stroke so I start watching for the rotor mark to align with the "T" mark. If I miss it and go past it, the exhaust valve will begin to open. That tells me I've gone too far and must continue turning the motor until the intake valve opens and closes again.

 

[highboy_coupe]

Thanks, interesting reading, wonder what 0.006 and 0.012. would sound like on my bike....

I believe I have done everything correctly from your explanation, thank you 5twins.

I just bought some Silkoline 20W50 mineral oil for air cooled engines, I have a feeling my diesel tractor engine is not helping at all. Plus, farmers have a tendency to refill old 40 gallon drums, so the label may not actually be what is in the drum....

 

[peanut]

5twins method description is perfectly correct of course allbeit unnecessarily complicated imho

Its so much easier ,( especially for someone unfamiliar with the process) just to put your finger over the spark plug hole and feel for the pressure building up in that cylinder . You know then that when the piston reaches the top of its travel TDC.... it is ready for setting the valves in that cylinder.

Yamaha in their wisdom have changed the recommended valve lash settings for this engine several times throughout their model range for reasons we can only speculate on.

If you read Howards extensive testing and results you will have a better understanding of the XS650 engine than most and can then make your own informed decision about which settings to use. Some set their valves somewhere in between the 2x settings and find the valves seat better for longer and the engine keeps cooler but the tappets are a little less noisy. if you set the valves tight at the recommended settings there is a big risk of having them too tight so that the valves never seat and gradually burn out plus you'll be losing compression.

Back when these engines were designed the settings were 0.006 and 0.012 and were noisy but then all bikes of that era were the same and nobody was at all bothered about a little tappet noise .

 

[Goldenboy]

I know it's really hard to judge from a crappy phone video which isolates the treble, unfortunately I don't have any "real life" XSs near by that I can go and inspect, so any input would be really helpful.

I replaced the missing washer on my cam-chain tensioner, which removed one metallic clattering noise, but.... I noticed the other noise has remained, which is more a tapping noise, it is not present when the oil is cold (I'm using 15W/40 tractor oil).
Now, I know I can't expect modern water-cooled levels of engine refinement, but this seems excessive, I might be wrong...

My cam-chain is tensioner to a point where with the engine running the rod never sticks out past the end of the adjuster nut.

My valves are at .003 and .006

I used a stethoscope at the points on the front of the engine where I have seen people check the front tensioner and there is no noise there, it seems more pronounced near the back right hand side.

I used the stethoscope all round really, and there wans't a point on the head where the noise suddenly became louder to me.

The head has been off at some point.

Thanks

Easiest thing to check would be for a bad tappet. I had one go bad and the tapping sound was pronounced. You can't hear it so well, though if you're dragging a washing machine behind you.