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I was in the process of checking the valve clearances when I came across an opening shim (horizontal inlet side) that looked very strange, with some kind of dimple around the center as if material was eaten away by the rocker arm. When i removed that one it confirmed my suspicion: there are 2 ridges that can be felt, and the surface looks nowhere as smooth as it should (the follower profile on the cam side looked perfectly fine). Has anyone ever come across such extreme wear patterns/damage?

Monster is a 2004 S2R 800, and has been running perfectly fine since the day I bought it (March 2020). Of course I will be replacing the shim and rocker arm with a new OEM one, because I don't see this NOT breaking in the future.

Any help/ suggestions are appreciated.

IMG_20210101_161240.jpg IMG_20210101_165955.jpg IMG_20210101_170244.jpg
 

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How was the clearance at the time you took it apart? If you normally do the valves yourself, do you remember if that's a factory size shim, or has it been lapped down?

I noticed again that you just got the bike in March. So it's probably your first time into it. That is a little strange. If the shim is marked, I'd see how it measures compared to the markings.
 

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I measured the opening clearance at approximately 0.127 mm (0.005"), but this measurement is probably a bit skewed because of the ridge on the rocker arm. If I think about it, without the ridge it would be bigger (remember that the ridge is 'carving' into the 'dimple' in the shim).

This is indeed the first time that I check the valve clearances on a Ducati (have done it before on a SV650), but I noticed that I'm not the first one doing it since at least one of the 8 checked shims has a thickness written on the side. The funny thing is that the bike has had no issues at all since March and was running perfectly fine (which I cannot understand when looking at the rocker arm haha).
 

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That is an odd one. Could be a million possible causes. I'm surprised more than 1 isn't marked. It's rare to get one that isn't. I would probably suspect a poor job lapping it by someone else who worked on it, or it could be a defective shim. However unlikely that is. Then work your way up the ladder from there. I'd check the top of the valve itself. Seek if it's getting rounded off from what looks like a wobbly shim.
 

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That is more than mildly alarming. I do not know if ducati case hardens their openers/closers. The shape makes me thing that maybe someone in the past perhaps lost a half ring in the gallery that ended up in between the shim and closer. My vote is for a top end rebuild.

Just a note, my openers and closers are bright, shiny, smooth, and clearly precision ground. This could just be a "5o'clock, drop your tools and go home" situation from the factory
 

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It does kinda look like the rocker was never finished out to begin with. Even though it's full range of motion only a small portion of that radius comes in contact with the shim. The irregularity runs along the full face of the area that should be machined and polished on the rough forgings. I wonder if the cam side was done?
 
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