Let's talk about cam walk, baby...

[bwringer]

This hasn't come up for a while, but I thought I'd start a discussion.

The video below is my 1983 GS850G, but the engine is actually from a 1980 or 1981 model. Long story, but this is the engine that's been in my bike for about 40,000 - 50,000 miles.

Anyway, these engines are known to sometimes exhibit "cam walk" at idle. This happens when a camshaft moves slightly side-to-side at idle and knocks against the cam caps. The noise disappears at higher RPM.

Thus far, the general consensus is that cam walk is considered to be harmless, just very annoying if you're sensitive to such things. There is no detectable damage or wear anywhere on the camshaft or cylinder head.

On my bike, the cam walk appears to be confined to the exhaust camshaft. The noise has been traced to somewhere in the center of the exhaust camshaft, and is strongest when the engine is partially warmed up. When the engine is cold, there's no noise, and when it's fully warmed up, the ticking is only occasional when the bike is upright or on the centerstand.

I've discovered that on the side stand at idle, with the bike fully warmed up, there's a strong, regular tick. I suspect this is simply because the camshaft can "fall" to the left with gravity at idle, then gets yanked back to center on the next revolution when the cam chain is tight. At higher RPM, anything at all above idle, the noise disappears because there's not time for the camshaft to move much.

Of course, cam walk may manifest differently on different engines. YMMV and all that.

• Yes, the exhaust is fully sealed (now THAT was an epic struggle).
• Yes, the valve clearances are perfect.
• Yes, the carbs are perfectly synced.
• Yes, the cam chain tensioner is functioning perfectly.
• Yes, the ignition system is working perfectly.
• Yes, the engine runs perfectly.
• Yes, the ticking disappears with any throttle input at all.
• No, it's not the clutch.
• No, it's not rod knock.
• No, there's not a little man with a little hammer living in there, at least not that I've found.

[bwringer]

FYI, another name for this, and more accurate, is "cam end float".

This is a document prepared by forum member Ian Grant (49er) back in 2007 documenting the sources of the issue and the machine shop work required to manage cam end float and eliminate the noise.

https://www.bwringer.com/gs/cam_end_float_mod.pdf

[Nessism]

I seem to recall some clever member, either here, or on the KZ site, machining some aluminum cam end plugs what limited cam end play, thus reducing the noise. I'll look around for that thread...

[bwringer]

I seem to recall some clever member, either here, or on the KZ site, machining some aluminum cam end plugs what limited cam end play, thus reducing the noise. I'll look around for that thread...

Yeah, controlling it from one or both ends really seemed like it could work well.

I don't remember seeing any parts, but I'd love to see some less invasive method of managing cam end float.

I'd buy a kit, but I'm not really interested in taking the engine apart again and having the machining done.

[Nessism]

Flip the cam end plugs around? Someone in this thread suggests that it helps...https://www.thegsresources.com/_foru...m-walk-options

[bwringer]

The camshaft ends are nowhere near the plugs, even when the plugs are flipped around. They're a few mm away.

Still, that points to a possible solution; make some aluminum or brass cam end caps thick enough to reach the camshafts, then remove material to suit the individual bike. You can shove the camshaft side to side and take measurements. Or make some sort of screw adjustable cam end plug.

However, the right side ends of the camshafts have notches, so they'd likely chew through softer metals. I'd imagine you'd want to control both ends of the camshaft.

[Rijko]

There is a Suzuki solution using shim plates.
3 shim sizes were made, still to be found on Ebay.
This solution only requires cam modification, no cam cap mods or half moon spacers.
This sounds like the cheaper option.

manual.jpg

[Rijko]

And the shim plates (ignore the handwriting, incorrect sizes)

shims.jpg

[Burque73]

Brian, thanks for posting that video. I've read a lot about cam walk but never actually been able to hear it before.

Does it seem to be more prominent in certain years of the two valve engines? There's around 55k miles on mine and still no noise like that.

[Rijko]

Buddy of mine worked as a motorcycle mechanic, and on bikes with camwalk he used to check the cams and cam journals.
He told me that the cam thickness nearly always was in spec, but the softer aluminium journals usually were on the high end of spec or over.

In some cases he was able to lessen or solve the camwalk by adding some thicker oil and/or setting valve lash closer to minimum.

[Rijko]

Flip the cam end plugs around? Someone in this thread suggests that it helps...https://www.thegsresources.com/_foru...m-walk-options

Thanks for that link Ed, Greg mentions 29mm shims .. i forgot about that but happened to me too.

Just a point - before going to the trouble of machining things, check that you haven't got an undersize shim.
Way back, I found a couple of yamaha shims fitted to a GS - about .5mm undersize on the OD...rattle city.

Took me a loong time to discover that, and made me check all my shims

[bwringer]

Brian, thanks for posting that video. I've read a lot about cam walk but never actually been able to hear it before.

Does it seem to be more prominent in certain years of the two valve engines? There's around 55k miles on mine and still no noise like that.

As I understand it, based on, er, 20 years (crikey, have I really been hanging around here that long?) of imperfect memory, this is a lot more prevalent on the earlier engines. On the GS850, it seems to be a thing that primarily affects the 79-81 models. My 1983 GS850G is wearing an earlier model engine, a 1980 if I interpret the available engine number charts correctly (the number on my engine is 116527, FWIW).

The '82+ GS850 models have different cylinder heads, so perhaps this was one of several details they changed. Until today, I had no idea Suzuki actually released a kit for dealing with this, so apparently they were aware.

I honestly don't really know whether or how much this affects other 2-valve GS engines, but there are reports here and there.

[uk gs nut]

I have done this modification to 3 GS engines, and it works fine. Square off 2 cam caps to fit brass shims to get end float 2 or 3 thou of an inch.

Camfloat tapping fix with shims gs 750 cylinder head by Dennis Harland, on Flickr

[jsandidge]

I had a machinist do the same mod as uk gs nut to my 82 850 about 5 years ago. It has worked a treat.

[GregT]

i didn't know they'd released a kit either.
My impression FWIW is that the problem is more prevalent in bikes which have a history of being warmed up on the sidestand.

At one point when i was in a shop servicing them, I asked about how they warmed the bike up. So some research - but not neccessarily conclusive.