Ring marks in cylinder?

Putting a new top end in my bike, and the cylinder has "ring marks" from the cylinder rings. Possibly caused by it being a leftover '11 and not being bought until this year and sitting with the piston in the cylinder for so long? I've been using scotch brite on a home made fixture for a drill to bring the crosshatch back, but these rings aren't disappearing. Checked the cylinder dimensionally on a cmm yesterday and everything checked out good, but are these marks a problem? You can feel them with your finger, but only barely. Bike had compression and ran good before the tear down. The second picture you can see the distinct outline of the oil ring. Would you run this or replace/re coat the cylinder? Or do you think a ball hone would do the trick?

ImageUploadedByThumper Talk1379170580.130868.jpg

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If I’m reading you correctly, you’ve unknowingly run the bike all this season with the cylinder being like that. If so, I’d run a ball hone threw there for a few strokes, install new piston and rings and ride it.

Putting a new top end in my bike, and the cylinder has "ring marks" from the cylinder rings. Possibly caused by it being a leftover '11 and not being bought until this year and sitting with the piston in the cylinder for so long? I've been using scotch brite on a home made fixture for a drill to bring the crosshatch back, but these rings aren't disappearing. Checked the cylinder dimensionally on a cmm yesterday and everything checked out good, but are these marks a problem? You can feel them with your finger, but only barely. Bike had compression and ran good before the tear down. The second picture you can see the distinct outline of the oil ring. Would you run this or replace/re coat the cylinder? Or do you think a ball hone would do the trick?

attachicon.gifImageUploadedByThumper Talk1379170580.130868.jpg

attachicon.gifImageUploadedByThumper Talk1379170591.536816.jpg

 

A ball hone will clean that right up, looks like some crusty oil has deposited on the cylinder.

 

You don't need to replate.

If I’m reading you correctly, you’ve unknowingly run the bike all this season with the cylinder being like that. If so, I’d run a ball hone threw there for a few strokes, install new piston and rings and ride it.

Yes. The bike was purchased new April of this year, and I bought it from the first owner with less than 10 hours on it. I did all the new bike prep, but it never crossed my mind to pull the cylinder on a pretty much new bike.

I'd be more worried about the condition of the big end of the crank.

I'd be more worried about the condition of the big end of the crank.

Just checked the connecting rod big end side play. It's within spec at .010. Is that what you were referring to?

No. Vertical movement.

 

If the engine has been sitting a long time, the damage is often not apparent for a hour or so of run time. What happens is a layer of rust/oxide forms (like you'd see on a car disk brake rotor). As soon as the rust is worn off, the rod develops vertical play. This can be heard as a slight knock/clank that will worsen in short order. Sometimes, with the barrel off and piston out, holding the rod small end in your fingers and slowly rotating the flywheel, you can feel any roughness (that is a sign of damage). If it is smooth as silk, you probably dodged a bullet.

No. Vertical movement.

If the engine has been sitting a long time, the damage is often not apparent for a hour or so of run time. What happens is a layer of rust/oxide forms (like you'd see on a car disk brake rotor). As soon as the rust is worn off, the rod develops vertical play. This can be heard as a slight knock/clank that will worsen in short order. Sometimes, with the barrel off and piston out, holding the rod small end in your fingers and slowly rotating the flywheel, you can feel any roughness (that is a sign of damage). If it is smooth as silk, you probably dodged a bullet.

There is no vertical movement, and it feels smooth. Is that a problem with leftover bikes?

I think it would be a potential concern for any bike that has been sitting around for a long time without lubrication, especially if there were big temp changes that led to condensation and/or potential for air to get into the system.  Steel rusts fast, and little imperfections in a bearing like that can be bad.  It would have helped to know the crank wasn't sitting in one place for such a long time.

There is no vertical movement, and it feels smooth. Is that a problem with leftover bikes?

Sometimes it is a problem. Often it is not. But it is something to pay attention to on a bike that has been sitting. Look for the wrning signs. If it is a problem, fix it as soon as it is apparent. The people that spend big bux on rebuilds are the ones that run it into the ground. I would not get worked up about it, just a little extra observant.

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