Pitted cam lobes.... uncool.... :(

[Warchild]

Well, not sure what to make of this, and obviously one data point doesn't mean diddly-squat anyway, still..... we have a lot of smart engine guys here, so perhaps some of you mechanically-inclined types can lend some insight/share your experiences.

You are looking at the pitted cam lobes of a 2008 Hayabusa (not mine!) with approximately 100,000 miles on it:

What is known thus far:

• Bike has (obviously) been ridden a lot - but never abused, drag-raced, etc. Just street riding, though a fair amount of it.
  
• Bike has spent a fair amount of time in mountain twisties, engine speeds tend to stay in the upper RPM range (though south of redline).
  
• Before 40K miles, oil was religiously changed every 3000 miles. After 40K miles - it was more like a 3-4K oil change interval.
  
• Unlike Suzuki factory recommendation, the oil filter was changed with every oil change. Always.
  
• Oil brand: plain 'oil everyday (factory recommended) Suzuki 4-Cycle Performance Motorcycle Engine Oil, 10w40
  

Again, one data point really doesn't mean anything. I haven't seen a lot of Hayabusa forum threads regarding pitted cams, so I am not thinking this is a huge issue here by any means. I have heard of Suzuki pitted cams before... as well as Kawasaki, Honda, etc.

It's just a little disturbing to see them on an engine just like mine...

I am approaching 70,000 miles on my K8, and I am not far off from having to check valve clearances again. You can best believe I will be paying close attention to cam lobes the next time I have a chance to inspect them.

 

[wfooshee]

One data point . . . . cracked wheel . . . . Hmm . . . . :lol:

Sorry, couldn't help it.

As for the cam, I think it simply comes down to metal quality. I've heard folks say it's water in the oil flashing to steam under pressure, and then gouging the lobe, but I don't buy it. I could more readily accept voids formed by uneven metal quality in casting, but I'm no engineer, really.

I've always been told not to worry about it, they do that as they get old. How much the do guys telling me this actually know? I'm not able to vouch for that.

EDIT: found the picture of my car's cams that had me concerned. This is a '95 Probe GT, with a Mazda-built twin-cam V6, about 145,000 miles. I circled the areas that I asked around about, and was told universally not to worry. Of course, in a car with hydraulic lifters under the cam lobes, this is something the customer is never supposed to see!

(The job I was doing was replacing the valve cover gaskets, which had become brittle and cracked and were leaking badly. Huge job on that motor, though, with the intake manifold folded over the valve covers, and water pipes going into the throttle body, and on and on. New gaskets were so soft that the cover bolt torque spec was in inch-ounces, maybe finger-tight plus half a turn.)

 

[03HiYoSilver]

Unfortunately, I've seen this on other 'Cycle makes as well on other forums.

I don't believe it has anything to do with maintenance but Slacked Quality Control across the board due to most likely tight margins and an unknown market.

Sadly, this is out of sight until the valves need to be checked and with most models, and way past the warranty period.

 

[Warchild]

Sadly, this is out of sight until the valves need to be checked and with most models, and way past the warranty period.

Fortunately, just like with Y.E.S., Suzuki offers a multi-year extended warranty that has unlimited mileage, so I still have a couple years left on my warranty, but.... I rather not have to go through the ***-pain (and down-time) of a camshaft R/R if I don't have to.

Suspect y'all are completely correct about the metallurgy aspect.... :huh:

I've always been told not to worry about it, they do that as they get old.

That would be nice if that was the case.... I don't have any direct, first-hand experience with pitted cams, not with any bike I've owned, so I can't really comment on this... but I am going to be VERY interested to see what the cam lobes are like come the next valve clearance check....

 

[Warchild]

EDIT: found the picture of my car's cams that had me concerned. This is a '95 Probe GT, with a Mazda-built twin-cam V6, about 145,000 miles. I circled the areas that I asked around about, and was told universally not to worry. Of course, in a car with hydraulic lifters under the cam lobes, this is something the customer is never supposed to see!

Interesting, wfooshee!

I *think* I would feel better if the pits in the Busa camshaft were small/dispersed like the ones circled in red above, but the disturbing aspect is that all the Hayabusa cam pits are generally in one location, clustered together at the business end of the cam lobe.

 

[Bounce]

I don't know about other brands, but Kawasaki owners have been posting about pitted cams on the C10 Connie. I went to look for some images and ran across other Kaws with the problem

30k on an ER5

{the image was hosted elsewhere in non-jpg. i've attached it for those who can see attachments}

15k miles on a ZZR

On a Concours with the comment (which I can neither confirm nor deny as accurate):

"Several years ago a fellow member had an interesting conversation with Frank at Crane Cams in Daytona Beach. He called them because he had noticed some pitting in some of his cam lobes. He had heard that they weld up and regrind damaged cams. Frank told the fella that the pitting which looks like "pin-holes" (which is what his looked like) is absolutely normal in cast iron cams, (and the same thing on cam followers) is just not a problem. He says the initial surface of the cam is only considered a "break-in" surface, and that the porous nature of cast iron makes the kind of pitting that was being seen inevitable. He said unless the cams and followers are actually gouged, and the cams scored around the circumference of the lobe, to forget about it. He said that real damage would be noticeable in terms of noise and performance degradation, and it is quite common for [owners] to become unduly alarmed at the appearance of cast iron cams with some miles on them.

 

[Fred W]

I *think* I would feel better if the pits in the Busa camshaft were small/dispersed like the ones circled in red above, but the disturbing aspect is that all the Hayabusa cam pits are generally in one location, clustered together at the business end of the cam lobe.

Exactly right, Dale. That does make them far more significant. What happens to the cam face in the area that it is not in contact with the valve bucket is of absolutely no consequence.

But, although the picture that you posted is pretty blurry, it appears that the "business ends" of those cams are actually scored only in the areas where they make contact with the back of the shim bucket, not pitted like Walt's car cams (which would have to be caused by poor casting).

This makes me think of improper oiling, excessive pressure, or overheating of those cam surfaces. This could have been caused by high rpms with high spring pressures (were they stock valve springs?) Anything that would increase the friction on the cam lobe. Of course it could still be that the cams were not properly hardened, in which case the scoring could happen at under normal operating conditions.

Edit - It would be of interest to see if there is also wear / scoring / marks on the top of the shim buckets under those cams.

Edit edit - Although we posted at the exact same time, Bounce posted about the notable difference between pitting and scoring also. I think that this is the key.

 

[wfooshee]

the Hayabusa cam pits are generally in one location, clustered together at the business end of the cam lobe.

Good point.

Now the head spins thinking about valve spring force versus RPM versus valve float, and the compromises engineered into the build to balance all of that with something people can afford to buy. Are the valve springs too stiff, but they have to be to run the RPMs you want? Is the cam lobe too soft, but really good metal would cost 2000 dollars more? That's beyond me, for sure.

When i posted my first reply, I hadn't noticed the scroll bar, and I didin't see both lobes of your picture. The one that was off my screen would have worried me more, for sure.

That said, they're nothing like the Kawi pictured above, which only has a thrid the miles!

 

[Afast03nNJ]

My buddy just had the same thing in his 749. Ducati said it's not that uncommon.

Bike only has 19K on it. Maintenance was up to date too.

 

[majicmaker]

That looks to me like the Normal Porosity Voids that are Inherent in ANY Casting that isn't to the Standards that (Lets Say) Rolls-Royce Quality Assurance Specs would be looking for.

I don't think this is anything to worry about because the engine will be Long Gone before it would start having Mechanical probelms that you would need to address.

 

[Auburn]

EDIT: found the picture of my car's cams that had me concerned. This is a '95 Probe GT, with a Mazda-built twin-cam V6, about 145,000 miles. I circled the areas that I asked around about, and was told universally not to worry. Of course, in a car with hydraulic lifters under the cam lobes, this is something the customer is never supposed to see!

Interesting, wfooshee!

I *think* I would feel better if the pits in the Busa camshaft were small/dispersed like the ones circled in red above, but the disturbing aspect is that all the Hayabusa cam pits are generally in one location, clustered together at the business end of the cam lobe.

What do the buckets look like?

 

[Warchild]

I don't know about other brands, but Kawasaki owners have been posting about pitted cams on the C10 Connie. I went to look for some images and ran across other Kaws with the problem

Damnation, those Kwak cam pitting areas looks horrendous!

What do the buckets look like?

I have an email into the owner.... he is having Yoshimura Performance cams installed as a replacement for these pitted cams, so I will see if there is any way to get photos of the buckets.

 

[Auburn]

I have an email into the owner.... he is having Yoshimura Performance cams installed as a replacement for these pitted cams, so I will see if there is any way to get photos of the buckets.

The reason I ask, I have a friend who builds top level road racing motorcycle engines for many different brands. He used to do Honda 900RR engines in the middle 90's for FUSA series. The cams were aftermarket from Costa Mesa. He ran one set in one engine all season that saw something like 15 race weekends running at the rev limiter. He set them next to a brand new set and you could not tell the difference expect the used ones had oil on them. They ran Red Line racing oil. I don't know if that made a difference or not, but it was stirking to see no difference. There was no wear onthe buckets either. He didn't do anything to mathce the cam surface to the buckets or anythign like that. The motor went from stock 105 rear wheel to somewhere in the 200 hp neighborhood with carburators.

 

[HaulinAshe]

Do I get to say... "This thread is useless without pics of the buckets!"

j/k of course. But the bucket surfaces will tell the other side of the story. heeheeheeheehee, Man! I'm on fire tonight!

I very much agree with earlier posts.

1. The pic is too blurry to make much determination.

2. It appears to be scoring caused by excessive pressure, insufficient lubrication or other non-design aspects; as opposed to casting/machining defects.

 

[Bustanut joker]

I'm with Ashe here.. Unless the porosity extends across the complete surface of the lobe longitudinally, the buckets will be needed to be examined to determine if these spots are in fact detrimental.

Porosity in cast iron can be avoided but when cost is a factor...I dunno.

I will say I've pulled and examined possibly 50 cams from vehicles "cars trucks" over the years. This phenomenon isn't uncommon nor is it detrimental. Unless the lifters are "scored" .....

 

[graler]

A lifetime ago I worked in a production machine shop. One of the several machines I has the opportunity to stand and watch run for hours on end was a crank shaft grinder. My job was to dress and fresh surface on the wheel and adjust the machine to make sure the shafts were the proper diameter and runout. They were two lobe shaft for air compressors just incase you were wondering.

Thats right this should eventually pertain to the thread.

Occasionally I would run across as group of shafts that had voids (pits) from the casting process. Air happens I guess. These pits looked very similar to those I have seen in the past.

I sure wish I had the access to all of those wonderful numerical comtrolled machines now. We would whip up some righteous farkles.

Joe

 

[slapnpop]

I'm with Ashe here.. Unless the porosity extends across the complete surface of the lobe longitudinally.....

:blink:

When the **** did YOU sober up?

 

[Bustanut joker]

I'm with Ashe here.. Unless the porosity extends across the complete surface of the lobe longitudinally.....

:blink:

When the **** did YOU sober up?

Back off Myron! The liquor store had an unfortunate power loss and the auto lock doors did their job.. I was thirsty for 17 minutes today. Ya *** chimp.

 

[majicmaker]

Molten Metal poured into a Casting Mold is Liquid. It's Boiling Liquid Metal. Just like in any boiling pot of water, The Bubbles are "AIR".

If it's literally poured by hand, that's Low Pressure. The Porosity Voids "Air Bubbles" are Large and Many because the molten metal will solidify before all the "Air Bubbles" are able to float to the top and Burst. If it's injected under High Pressure, They will be small if any. That's just the Nature of the Beast.

There is Nothing you can do about it. The Higher the Pressure the Better. Inexpensive Engine Parts (And That's what we have whether we like it or not) will Accept a certain amount of Porosity knowing that it will not present a big problem in the life of the Part. That's Keeping their cost down for the Bike that we ALL Love.

Rolls-Royce sends me Castings to X-Ray on a regular basis and they don't want ANY or they'll accept Very Tiny Voids and as far away from eachother as possible.

That costs them a lot of Money. That's why their Cars and Jet Aircraft Engines cost a KaZillion Dollars. I look at Porosity on X-Ray Film for a Living.

That's what that looks like to me. I may be wrong but, I doubt it!