Pitting on cam lobe - should I worry?

[MrZig]

I just bought a 1982 GS400 motor to put in my bike. The salvage shop owner said it ran great before they pulled it. Unknown KM's/Miles.

I took the valve cover off (gasket came off in one perfect piece, too!) and the valves weren't too far off. The left exhaust was actually in spec - so it at least seems maintaned.

Problem is, I found some pitting on the cam lobes. The most serious was this, feelable by fingers:



Is it something to worry about, or will it just be something to monitor on each valve check?

I googled it and it seems most common on low use engines. On my pre-installation tuneup I also took the oil pan off to check around and clean the pickup screen. I found some dirt and a few small metal flakes in the bottom of the pan - perhaps they're from the cam lobes, or maybe just from initial break in? It was nothing serious looking, just a few shiny flakes here and there.

The oil pan was stuck on pretty hard and the gasket ripped when I took it off so I doubt it's ever been off before, so my hypothesis on the engine-breakin flakes could be correct, right?

[rapidray]

It looks to be BELOW the surface like it was just that the metal was a little porous when machined. I would just keep a watch on it at each valve clearance check. Ray.

[TheCafeKid]

I have the same thing on my 1100ES..was pretty nervous about it, both Blowerbike and Ray seem to be right on on this..i havent seen anything that would lead me to believe that its doing any damage as ive been watching mine..

[frosty5011]

On low-performance bikes, such pitting usually is not a problem and you probably need not concern yourself with it.

However, were it a high-performance machine, like the "L"s, then I'd be very worried!

[Nessism]

I've seen that kind of wear on cams before and it indicates high pressure failure of the cam. It's on the edge of the cam which indicates that the two valves were not adjusted to the same clearance and the rocker was twisting thus wearing one edge of the cam. The rocker most likely has the same type of damage.

I've mentioned this type of wear here before and a few members dismissed my comments. This is why I don't like the 16V engines as much as the 8 valve engines in terms of cam wear.

BTW, I rebuilt a Kawasaki EX500 engine and it has the same issue. I had to buy several cams and rockers off ebay before I could find enough parts to put the engine together (photos below).

As for what to do I strongly recommend using synthetic oil like Rotella and double checking your valve clearances using two feeling gauges at the same time to verify clearance - you want both valves to have the exact same clearance on each pair of valves sharing a rocker arm.

Good luck.

[MrZig]

Thanks for the help. I'll keep an eye on it every valve check. I also already have rotella 15w40 that I'll run in it, but I'll change it out with the synthetic 5w40 next spring (if I still have it!).

On the good news side of thing, I got the engine in!

Lifted it in myself. Holy god is that ever a heavy mother. Took some wiggling and some prodding but it popped in. (It's sitting on one of the mounts in the picture but I managed to drop it in no problem)

[TheCafeKid]

Hrmm..Ed, i think i can see your thinking on this, but, at least on MY cams, the pitting ISNT on the head of the lobe, where one would thing that the MOST stress is endured. Mine instead is either on the back side or flat sides, where, it would seem to me anyway, the LEAST amount of stress would be, since it has limited contact and next to no pressure on the valve spring via the rockers?? Am i completely foolish in this line of thinking?

[gearhead13]

Thanks for the help. I'll keep an eye on it every valve check. I also already have rotella 15w40 that I'll run in it, but I'll change it out with the synthetic 5w40 next spring (if I still have it!).

On the good news side of thing, I got the engine in!

Lifted it in myself. Holy god is that ever a heavy mother. Took some wiggling and some prodding but it popped in. (It's sitting on one of the mounts in the picture but I managed to drop it in no problem)

Bah! thats just a twin, try a 4 cylinder like mine, lifted it in myself

[MrZig]

Bah! thats just a twin, try a 4 cylinder like mine, lifted it in myself

How in the world did you manage that? It must of weighed more than 200 pounds.

[Nessism]

Hrmm..Ed, i think i can see your thinking on this, but, at least on MY cams, the pitting ISNT on the head of the lobe, where one would thing that the MOST stress is endured. Mine instead is either on the back side or flat sides, where, it would seem to me anyway, the LEAST amount of stress would be, since it has limited contact and next to no pressure on the valve spring via the rockers?? Am i completely foolish in this line of thinking?

That's a good question Josh. If the wear is on the base circle it can't be due to high pressure failure. Next time you have the valve cover off your bike shoot a couple of photos and post them so we can review.

[gearhead13]

How in the world did you manage that? It must of weighed more than 200 pounds.

I used to deadlift over 400 Lbs when I was weightlifting