850 Engine Noise

[Steve]

I'd hate to tear it all down for gaskets and then discover once it's back together that it burns oil and have to tear it down again.

Where motorcycle engines differ from car engines is in the way they are designed. Yes, the valves are still in the head and there are seals around the valve stems, but when you remove the head on a bike engine, you will disturb the gasket at the base of the cylinders, requiring pulling the cylinders off the pistons to change it. Pulling the head on a car engine is comparatively easy. That is why we tend to do some preventive stuff "while we are in there".

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[Gorminrider]

Is it just the "shim" bikes that exhibit cam-walk? and is it just the 4 cylinder bikes?

My screw-adjust tappets on GSX twins do not do this. I wonder: do the GSX 4s?
It's too bad...re-selling a bike that is "glock-glock glocking" at the top end is not so easy...buying one without fore-knowledge is discomfiting.

[Steve]

Is it just the "shim" bikes that exhibit cam-walk? and is it just the 4 cylinder bikes?

Good question.

I wish I had a good answer for it.

I don't do much work on twins, also don't do much on "non-shim" bikes, so I have not noticed whether they have cam walk or not.

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[John Park]

Is it just the "shim" bikes that exhibit cam-walk? and is it just the 4 cylinder bikes?

My screw-adjust tappets on GSX twins do not do this. I wonder: do the GSX 4s?
It's too bad...re-selling a bike that is "glock-glock glocking" at the top end is not so easy...buying one without fore-knowledge is discomfiting.

I replaced all the shims on my 450 with new OEM gs500 ones which appear to be some sort of sintered metal [??] and the cam walk racket went away and has never come back. I'm suspecting that a shim which isn't dead square or maybe worn concave could induce cam walking. Given that the shims were readily available and cheap.....that said, GS500s were known for cam walk and various measures were tried by Suzuki such as a sprung endplay shim to cure it. It seems as though either having so little endplay that the cam can't get a run at its destination or so much that it changes its mind before it gets there can relieve it.

The head expands way faster than the cam, so achieving a constant endplay is impossible. The beauty of bucket followers is that they rotate and present a constantly changing face which avoids the grooving and galling that can plague lever type followers. However, in order for them to rotate, the cam lobe is slightly off center which induces a side motion which reverses as the lobe goes over center. The GSX motors shouldn't, in theory, have cam walk.....

[Gorminrider]

Ah,so! Between yours and Steve's explanation (post2), I can pretend to have an intelligent handle on it! And I now know it's a feature of the "shim 'n bucket" twins too.

[Steve]

All I can say for sure is that I can't hear it once the bike is moving, so it must not really matter.



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[Gorminrider]

I replaced all the shims on my 450 with new OEM gs500 ones which appear to be some sort of sintered metal [??] and the cam walk racket went away and has never come back

. That sounds very hopeful. I wonder at the "why" of it...friction coefficient? I know you use hi-grade oil too, if this might have any effect..

and various measures were tried by Suzuki such as a sprung endplay shim to cure it

this is something that comes to mind.. I'm keeping an eye out for thin "warped" spring washer for each cam end maybe just glued to the rubber end seals...... or maybe just bit's of hdpe as experiments... It kind of agrees with one member's fix- paraphrasing, I think he said "turning the cam-end rubber around" .

It's also been said that leaning the bike over removes the noise....I haven't experimented with this but it'd be a demonstration to anyone that the noise they hear is indeed "cam-walk" and would save posting (or trying to listen to) Youtube videos...
The documented"machinist" option is never going to happen in my shed .

[Steve]

It's also been said that leaning the bike over removes the noise....I haven't experimented with this but it'd be a demonstration to anyone that the noise they hear is indeed "cam-walk" and would save posting (or trying to listen to) Youtube videos.

If leaning the bike over removes the noise, it must have to be leaned over farther than what the side stand allows.

My wife's bike does it the worst of our three bikes, it is plainly audible while on the side stand.
Usually not very noticeable when cold, it's louder when the engine is warm.

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[93Bandit]

If leaning the bike over removes the noise, it must have to be leaned over farther than what the side stand allows.

My wife's bike does it the worst of our three bikes, it is plainly audible while on the side stand.
Usually not very noticeable when cold, it's louder when the engine is warm.

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Mine is the same. I've noticed no difference between the bike on the side stand vs. sitting at a light with the bike vertical. If the engine is up to temp and idling, it clatters.

However I'm no longer worried about it. I was only concerned because I didn't know what the source of the noise was. Now that it's clear it is caused by cam walk, and many members here have the same noise with no obvious ill effects, I will continue to ride into the sunset without worry.

[Gorminrider]

A sidestand lean makes no diff to my (warm) bike either but I do think I saw as a single post in a thread- it wasn't said how far the bike needs to be leaned...up to 45 degrees I'd guess so it's not something I'll do on gravel.

I can live with the clatter, but I don't like it.

[John Park]

A sidestand lean makes no diff to my (warm) bike either but I do think I saw as a single post in a thread- it wasn't said how far the bike needs to be leaned...up to 45 degrees I'd guess so it's not something I'll do on gravel.

I can live with the clatter, but I don't like it.

On a twin, I had the evil thought of slightly slotting the dowel holes on one of the cam caps and sliding it inwards to take up the endplay. You'd still be left with whatever develops from expansion, but at least you'd be starting at zero. Not having a four about to examine, I couldn't tell you if there would be a similar relevancy.

By the look of it, you'd have to move over about .020 or .5mm to get 'there' and then whatever clearance there is. Not really a job for a round file unless you are patient and talented.

My spare engine head is from an '80 and a set of late 80's cams fit in with zip endplay; weird but I'll take it. Now I just need a reason to build the motor up and swap it in, but the wear rate on me seems higher than on these motors...

If I were really in a state of annoyance I'd consider making a replacement half moon with a spring loaded ball bearing to sit in the cam center hole. It wouldn't be that hard if you made a round plug with an o ring groove and then milled off half the circle. The effect would be similar to having the bike leaned way over all the time, and even if the ball fell out somehow it has nowhere to go.

BTW, I missed which model of bike you're having the problem on. 650 twin?

[Gorminrider]

John, OP has an 850, but yes, I have a 4 too- a 650G that at first I used to wonder if people alongside at the light were thinking, "Nice bike-too bad the thing it needs engine work"

...of course they are not, with the windows rolled up in diesel pick-ups, airconditioning on, and yacking on their cell-phones.

a spring loaded ball bearing to sit in the cam center hole

Beauty! keep it up man! I'm thinking on my spring collection already! Ball bearings, I have a-plenty...I wonder just what side force is required to "control" the cam's travelling ?
The ball bearing idea is a worthy start! With the rubbers off, I might drill a hole for a spring into a broomstick and just push the ball bearing against the cam for a test...

[John Park]

Beauty! keep it up man! I'm thinking on my spring collection already! Ball bearings, I have a-plenty...I wonder just what side force is required to "control" the cam's travelling ?
The ball bearing idea is a worthy start! With the rubbers off, I might drill a hole for a spring into a broomstick and just push the ball bearing against the cam for a test...

I don't think you'd need much force at all. An insert to fill the space between the half moon and cam, with a hole to hold the ball captive and a spring against the reversed half moon might be something simple enough for us rustics to cobble up.

[Gorminrider]

I've got the 650 in the shed now, (cleaning up the rear brake etc. before reinsuring this year) so the timing is good to do some tinkering as well....

[Gorminrider]

well, refreshing my memory of these cam-end seals with reality, I see that the "meat" for

An insert to fill the space between the half moon and cam, with a hole to hold the ball captive and a spring against the reversed half moon might be something

isn't available without a little more thought-these cam-end seals are hollow construction...so they'd want to be filled up with something. MEANWHILE, simply reversing them as a learning exercise is too easy an idea to pass up..here shown reversed- and the next post due to picture limit.
Gs650-camwalkfix-reverseCamendSeals-1-20190328.jpg