My friends 15k mile Duke 890 r dropped an intake valve last week and we're looking for possible causes. After opening it up, we found severe cam and rocker wear but not a good reason for the cause of that either. He is the second owner and bought it with about 4k miles on it. it has not been beat on, has had regular oil changes and ran fine up to the failure that happened when he shifted to 2nd at pretty low RPM on his way home.
My first thought was that the oil squirters for the two worn cam lobes was clogged. I checked them with an oil squirt can and they spray right out.. I then checked the cam oil feed screen and it is clean.
I know this engine made a lot of metal at some point but my friend said he saw nothing in the oil screen on his first oil change. i don't think he checked them this last change.
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The cause of the intake dropping was a broken valve spring retainer. The question is, why did it break? I'm suspecting it might be the result of the huge valve gap due to the cam and rocker wear.
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My first thought was that the oil squirters for the two worn cam lobes was clogged. I checked them with an oil squirt can and they spray right out.. I then checked the cam oil feed screen and it is clean.
I know this engine made a lot of metal at some point but my friend said he saw nothing in the oil screen on his first oil change. i don't think he checked them this last change.
The cause of the intake dropping was a broken valve spring retainer. The question is, why did it break? I'm suspecting it might be the result of the huge valve gap due to the cam and rocker wear.
