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Discussion Starter #1
Hi. Strange things are happening in my 998. When i bought it three years ago, it had two torn stem seals in the head of the vertical cylinder. I noticed this while changing a few bad rockers. (yes, in a 998). i could see that the rockers made contact with the seal when the valve was compressed, so i was happy to find that the used rockers i bought of ebay had a little less material in the spot that made contact with the seal, thus preventing contact. They looked original, and was a perfect fit, so i assumed it was a part that Ducati had made changes to.
Now, three years and 8000km later, i open her up for a valve check, and find.... A torn valve stem seal? what is going on? Is it just my duc that does this? The seals arent all that expensive, and the bike hasnt used oil, so maybe i should just accept the italian way?
Or is there a fix?
 

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The first time that you opened it, perhaps you saw the result of bad work from the previous owner. In my opinion the bad rockers are the give away on that.

As to the currently bad one, is it one of the two that were previously replaced?
 

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Discussion Starter #3
The first time that you opened it, perhaps you saw the result of bad work from the previous owner. In my opinion the bad rockers are the give away on that.

As to the currently bad one, is it one of the two that were previously replaced?
Yes. Vertical cylinder right intake. Last time it was two vertical intakes
 

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Is there a chance you pinched the seal when you used forceps or the clamp to hold the valve while swapping shims and replacing the rockers? It's easy to do.
 

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You might compare the exposed length of the valve guides to a known stock example.
 

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Discussion Starter #6
Is there a chance you pinched the seal when you used forceps or the clamp to hold the valve while swapping shims and replacing the rockers? It's easy to do.
There is ofcourse always a risk that something like this happened. But the seal is torn apart now, not just pinched


"You might compare the exposed length of the valve guides to a known stock example." I wil try to measure the length of the exposed valve stem. Does anyone have an idea where i might get a comparison measure from?
 

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nick on the valve stem???
 

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Discussion Starter #10
do you use a protective sleeve over the valve stem to prevent tearing the seal?
It has been three years, but if i remember correctly, i had a piece of plastic over the valve. But the valve is not just leaking, it is torn to pieces. To the best of my knowledge, there are no knicks on the valve stem. I will check up on that tomorrow
 
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