Cam pitting cause??

[Desertsky]

Here is a theory that I can provide some backup for:

The #4 intake cam is the first one to pit because of insufficient lubrication. I have also heard (and saw some evidence) that ZX11s do the same thing. My bike pitted three sets of cams in 40k miles all the while using Amsoil and Mobil 1 oils.

The backup? Look at the pictures:

My ZRX rocker tubes:

Tubes from spare ZX11 head:


I had another set from another ZX11 head that looked the same.

The oil holes on #1-3 are larger in diameter and aren't blocked as much.

The intake tubes are at the bottom of both pictures. Notice the wear marks from the rocker arms and the position of the oil holes. Since the #4 cylinder area has holes on only one side of the tube and the rest of them have holes on both sides, it is clear that little to no oil is getting into the rocker oil hole to lube the cam lobe. All of the holes are offset the same amount so I believe that the holes bored into the cam towers for the tube were bored too far into the intake side. I will be adding a 1mm shim to the intake side to help line up the holes with the rocker oiling area.

It would be real interesting to see the condition of other engines that have eaten intakes cams.

[SteddyTeddy]

[storm42]

I have no wear on my cams but I will be checking that out when I pull the head later this week.

[KWICK]

The holes are not drilled in the tubes in the same places either.

[The Judge]

you should use dino oil--


---you should use 10W minimum--


--you should use Z-max--

[Desertsky]

The holes are not drilled in the tubes in the same places either.

That is because the top tube in each picture is for the exhaust side. The spacing is different.

[KWICK]

That is because the top tube in each picture is for the exhaust side. The spacing is different.

I feel like the stupidest cat in the jungle now....my head will be apart today for inspection....how many guys know this? I think the cam wear mystery has just been solved.

[SteddyTeddy]

Just checked the spare head I have. All holes are dead center where they belong and yes the intake and exhaust tubes are different.

[Desertsky]

I feel like the stupidest cat in the jungle now....my head will be apart today for inspection....how many guys know this? I think the cam wear mystery has just been solved.

I knew something about a ZRX Pete didn't????

[Desertsky]

Just checked the spare head I have. All holes are dead center where they belong and yes the intake and exhaust tubes are different.

I wonder if they "fixed" it on the 1200s?

[dimora]

I wonder if they "fixed" it on the 1200s?

My Muzzy 1200 cams (ZZR knockoffs, or maybe identical - who knows what Muzzy did?) are pitted as well.

[Copyguy]

I can see where a lack of lube will "score" a cam lobe face where it contacts the rocker, but that isn't "pitting," which appears as an "etched" surface that meanders in a short line.

I bought a set of used 1200 cams - the faces of the lobes are perfect (no scoring or pitting), however, one of the lobes does have slight pitting on the face at the point opposite the contact point.

As I understanding "pitting" from prior posters, it's not a function of lubrication (or absence thereof), rather it's a failure of the cam's manufacture - either through inclusions in the metal, from a cheaper form of face hardening, or both.

All info appreciated on this topic. By the way, Canadian Chrome and Crankshafts apparently will harden stock cams the right way for $180 total, per a poster on the Concours board.

[Desertsky]

I can see where a lack of lube will "score" a cam lobe face where it contacts the rocker, but that isn't "pitting," which appears as an "etched" surface that meanders in a short line.

I bought a set of used 1200 cams - the faces of the lobes are perfect (no scoring or pitting), however, one of the lobes does have slight pitting on the face at the point opposite the contact point.

As I understanding "pitting" from prior posters, it's not a function of lubrication (or absence thereof), rather it's a failure of the cam's manufacture - either through inclusions in the metal, from a cheaper form of face hardening, or both.

All info appreciated on this topic. By the way, Canadian Chrome and Crankshafts apparently will harden stock cams the right way for $180 total, per a poster on the Concours board.

The severe pitting on my last cam was a classic fatigue failure. Looking at the failed area under magnification shows the stress cracks and crystallization of the metal. I see the same thing in model airplane engine bearings where the lube used is too low viscosity and poor quality. My supplier's engineer says it is most likely from micro-annealing (small areas getting hot enough to lose heat treatment). Sounded similar to microwelding of bearing surfaces.

[roadrogue]

So is that cam pictured still useable or is that asking for trouble?

[Desertsky]

So is that cam pictured still useable or is that asking for trouble?

As far as I am concerned, it is toast. The amount of missing metal is greater than 50% across several areas of the contact line.

[Copyguy]

That damage, to my understanding, is "pitting" (by whatever cause). "Scoring" is the longitudinal scrapings that appear on the lobe face at/around the contact point. I've got pitting to a much more minor degree on my used cams, but only on the back of the lobe, where it doesn't contact the rocker.

Do I understand you intend to drill add'l holes in the #4 intake rocker so they match the others, AND shim the tube so its holes line up with the rockers as a means of getting more oil to the cam lobe and prevent the pitting?

[KWICK]

Fix for bad cams....
I just opened Calista up after 2000 miles and two Willow Springs track days with her hardwelded Yosh intake and I can safely say that it is PERFECT!!

If anyone wants a cam or two reground to ZZR/ZX11 spec or Yoshimura specs I can have it done for you. It takes about 3 weeks.

Really, this cam looks brand new! ...and, it was wasted before I sent it in.

[blitzkraig]

Are there any other differences between the exhaust and intake rocker tubes? Could two exhaust tubes be used?

[KWICK]

Are there any other differences between the exhaust and intake rocker tubes? Could two exhaust tubes be used?

The holes are in different locations...that is one of the problems...if you install the shafts in the wrong spots you could cause the wear we have seen.

How many of you that have had your heads apart were aware that the rocker shafts were different?

[Desertsky]

Are there any other differences between the exhaust and intake rocker tubes? Could two exhaust tubes be used?

The spacing between the rockers is different so if you used an exhaust tube in the intake position, the oiling would be almost non-existent.

[Desertsky]

Do I understand you intend to drill add'l holes in the #4 intake rocker so they match the others, AND shim the tube so its holes line up with the rockers as a means of getting more oil to the cam lobe and prevent the pitting?

No, the oil holes are the right diameter. I only intend to shim it out so that the holes are in the right place for the rockers.

[Copyguy]

No, the oil holes are the right diameter. I only intend to shim it out so that the holes are in the right place for the rockers.

Ahhh. I was going by this from your original post: "Since the #4 cylinder area has holes on only one side of the tube and the rest of them have holes on both sides, . . . . "

I thought you might be adding holes to the other side of the tube for #4.

I'll bet some folks have pulled those tubes and swapped them upon reinstallation.

[djoneill]

Cam pitting is known problem for tappet engines running new formulation oils w/low levels of zddp.

Have you been running motorcycle specific oils with zddp?

[Desertsky]

Cam pitting is known problem for tappet engines running new formulation oils w/low levels of zddp.

Have you been running motorcycle specific oils with zddp?

Are you speaking only about motorcycle engines or tappet engines in general? I find it hard to believe that the millions of tappet engines in cars around the world would have this same problem due to oil formulation.

My normal oil is Amsoil motorcycle specific oil.

[djoneill]

I'm just the messenger here- this is a very well known problem.

Your motorcycle oil probably includes plenty of ZDDP, so sorry for the diversion.

[Desertsky]

I'm just the messenger here- this is a very well known problem.

Your motorcycle oil probably includes plenty of ZDDP, so sorry for the diversion.

I guess what I was trying to say was that if pitting was a well known additive problem, the engine manufacturers would have forced the SAE and oil manufacturers to address the problem. I, personally, have never seen it or heard reports of it.

There is lots written and a lot of research done, mostly pointing to overloaded surfaces and/or insufficient lubricant. No mention of additives playing into it. I have read a couple of reports that talk about reduced clearance when the engine is hot possibly causing the oil film being reduced.

I believe that the problems I have seen, and evidence from a lot of other engines points to the rocker tube offset issue that I found with three different heads (ZRX1100, ZX11D and ZX11C).

http://www.ciba.com/pf/docMDMS.asp?t...ocnumber=29309
http://www.v4honda.com/knowledgebase...gine_DD206.htm

Kawasaki GPZ750R: "Cam pitting was cured by a switch to larger oil pipes (6.4mm rather than 4.8mm), plus new banjo bolts."

http://books.google.com/books?id=Oor...um=4#PPT203,M1

[C.Jay]

This is a great thread, you guys know more than the MamaKaw injuneers!!!

Keep up the good work.

[eddy21]

I think he means vintage cars and Hi -po. Idling them at break in is the worst thing.

[Grebnaws]

Add me to the list. Many of my cam lobes, intake and exhaust, are pitted. I didn't record which before finishing the valve adjustment. Pretty depressing to see severe pitting on a 2004 bike with 15k miles, 5k under my care with 3 oil changes in that time.

Mama kaw better get their crap together. Have they admitted the problem? Any recourse?

[motahead70]

I've been waiting to get my bike back after a minor altercation with a sign post and I received a call from the shop this morning telling me they found a 'warranty issue' while replacing the rocker cover that was scratched in the accident. Pitting and hardfacing coming off the lobes. 07 1200r with 13500km on the clock. The shop said Kawasaki prefer to have the original built up and reground over replacing with the genuine article. Sounds like they know damn well there's an issue. The local shop has another ZRX1200(don't know what year) there with 46000km with the same problem and i believe warranties covering it as well.