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Scratches on cam lobes after ~30 km ride 06 Jun 2024 05:58 #900339

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Could the camshaft have been turned while there was no valve shim in the follower?
No

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Scratches on cam lobes after ~30 km ride 06 Jun 2024 06:27 #900345

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Hello everyone! Recently did a head rebuild on my '82 KZ1100. Went on a first ride and after it a few of cam lobes are a bit scratched. Definitely weren't any scratches you can feel with fingernail like those before. Found this accidentally,had to change one shim for a bit smaller one.
Anyone had similar situation?

 
Looks mighty dry in there.  We'd expect to see oil pooled in the low area below the bucket.  Oiling issue?  What do the cam bearings & shims on the damaged lobe side of the head look like?

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Scratches on cam lobes after ~30 km ride 06 Jun 2024 10:19 #900369

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I'd drain the oil and send it in for analysis.. Pull the filter and open it up to see if there is any metal inside.
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Scratches on cam lobes after ~30 km ride 06 Jun 2024 14:29 #900380

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Drained the oil and pulled out the filter- nothing found. Oil doesn't look like new but no debris or any hard chunks in it or in the filter.

Looks mighty dry in there. We'd expect to see oil pooled in the low area below the bucket. Oiling issue? What do the cam bearings & shims on the damaged lobe side of the head look like?


I didn't take off cams since it's been just about 30 km since I put it together. Managed to change one shim with cam on its place. 
What can be wrong with oiling? Would checking oil pressure do any good?
Oil lamp turns off when the bike start running.
The new head gasket is 2 piece just like the old one and I changed all 4 o-rings for oil passage around the studs as well.
 

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Last edit: by KZ 1100.

Scratches on cam lobes after ~30 km ride 07 Jun 2024 04:24 #900412

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Just a hunch.  But, cannot discount the observations of others about debris from grinding the head of the socket bolt either. 

Both scratched lobes appear to be on the exhaust cam at #3 and #4.  That end of the exhaust cam shares a common oil supply from the right front corner stud feeding the exhaust cam bearings between #3 and #4 (cam cap #2 in the photo).  From there cam lobes are lubed by splash, or, more accurately, drooling out the ends of the cam bearings.  That there's no oil pooled below the #4 exhaust cam bucket looks suspicious.  Can't see that area of #3 in the pics.

Is oil pooled in the low area of the head below other cam buckets?

EDIT: Hot oil pressure on an air-cooled 4 cyl. Z-bike motor is only around 3 ~ 5 PSI, lower at idle.  The only plain bearings are the cam bearings which are so lightly loaded that the presence of any oil film at all is mostly sufficient lubrication, and are responsible for most of the pressure that can be read by a gauge that does develop.  The remainder of the bearings in the motor are ball & roller.  They depend on volume rather than pressure to live.  Oil pressure gauges that can accurately read in the low-to-mid single digits are uncommon.

Good Ridin'
slmjim & Z1BEBE
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A Rider looks at your odometer and tags.

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1974 Z1-A x2
1975 Z1-B x2
1993 CB 750 Nighthawk x2
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Last edit: by slmjim+Z1BEBE. Reason: Clarity

Scratches on cam lobes after ~30 km ride 07 Jun 2024 04:55 #900417

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Just a hunch.  But, cannot discount the observations of others about debris from grinding the head of the socket bolt either. 

Both scratched lobes appear to be on the exhaust cam at #3 and #4.  That end of the exhaust cam shares a common oil supply from the right front corner stud feeding the exhaust cam bearings between #3 and #4 (cam cap #2 in the photo).  From there cam lobes are lubed by splash, or, more accurately, drooling out the ends of the cam bearings.  That there's no oil pooled below the #4 exhaust cam bucket looks suspicious.  Can't see that area of #3 in the pics.

Is oil pooled in the low area of the head below other cam buckets?

Good Ridin'
slmjim & Z1BEBE

Only the first cylinder bucket is full of oil. Other have just a drop or few. Although lobes feel like greased with oil, not like they were totally dry. On the photo you can see traces of oil on cam cap as well...
What could be wrong with oiling?

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Scratches on cam lobes after ~30 km ride 07 Jun 2024 05:07 #900418

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Are you sure the hole in the lower cam bearing is not plugged / obstructed ?

After reading your post above it seems your not getting enough oil on the top end at all, there should be much more than a drop or two sounds like the screen is blocked with debris,

I had a cam cover plug pop out on a test ride and my leg was covered in hot oil in seconds.

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Last edit: by Moose1800.

Scratches on cam lobes after ~30 km ride 07 Jun 2024 12:02 #900431

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This may sound like a dumb question but what kind of oil are you using? I have seen similar damage when using conventional automotive oil (car oil)

Its also no big deal to run the engine with the cam cover off, it just gets messy once the oil splashes around. This is a good way to make sure oil is getting to the cam lobes. Once the engine heats up on a longer ride the smoking will stop.
 

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Last edit: by Injected. Reason: sp

Scratches on cam lobes after ~30 km ride 07 Jun 2024 13:50 #900432

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This can be sand/smallstones/metalparticles  that found its way into camcover when off.if it was  laying with inside up .
I can se the cover laying on the floor in one pick it is easy to drop something in there not saying you did but its a possibility.
About the aperance of not oil in the lifter space that is not uncommon when bike has standing on sidestand
for five days and it is cylinder 4  the oil drains down.I can see oil in the bearing space under the camcap  so it is lubed .Do you use synthetic oil?

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Last edit: by Rolf1976_KZ900.

Scratches on cam lobes after ~30 km ride 08 Jun 2024 09:57 #900455

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Just ran it without cam cover. See no problem with exhaust lobes oiling. However the 4th cap seems to have the least of it and while you can see the cam in the middle of the cap (between bearings) bathing in oil on other 3, with 4th it's just slightly lubed.  Third intake isn't filled with as well.

In the bike I have fully synthetic 10w-40 Fuchs silkolene pro4. 
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Last edit: by KZ 1100.

Scratches on cam lobes after ~30 km ride 08 Jun 2024 10:29 #900456

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Dump the fully synth and re-fill with jaso spec semi 10/40 such as Fuchs super 4 .
The roller crank hammers fully synth oils.
The only fully synth i will use in these is Rock oil TRM20/60 which is formulated with long chain molecules specifically for use with roller cranks.
As for the cam lobes.
What kind of lube did you use on the cam shells.
Excessive use of assembly paste can actually plug the oil holes in the shells and restrict the oil path to the cam and followers until the paste is flushed out after a few miles so that may the cause of the scoring.
With no oil supply at all your cams would likely be destroyed within 30 miles so you either have a restricted supply or they experienced a dry start which cleared after a short while..



 
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Last edit: by zed1015.

Scratches on cam lobes after ~30 km ride 08 Jun 2024 10:34 #900457

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Cam shells? 
You mean bearings? I just lubed it with engine oil that's all. No special stuff used.
What do you think about 4th cap?

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