cylinder wear

[jordan83]

is it normal to see where marks in a cylinder after low runtime on a new topend? just like some vertical glaze lines? thanks

[eprovenzano]

Can you give us some more details.  And if possible, can you post a picture as well.

[jordan83]

sorry cant get a pic. they are vertical lines in the cylinder. just like discoloration. like a glaze. i can still see the hone marks behind the marks. theres some in different spots around the cylinder bore. that help?

[DangisMX]

It could mean that dust is getting inside the cylinder.

[jordan83]

so its not normal then?

[DangisMX]

I think not. It will reduce the lifetime of your engine. I once had this problem because I was riding in sand a lot (very dusty). I can't tell if it's the same issue in this case, but it sounds similar. Do you clean your air filter, is it installed properly? Maybe somewhere between the filter and the carb there's a hole?  

I guess there could be some other things that could cause this, but in my case it was simply dust.

[jordan83]

that sucks man. just had the cylinder replated and shit. damn

[jordan83]

so i should prolly tear it back down again thenand check rings and everything?

[Chokey]

Are they fine scratches or simply bands of discoloration? Do the marks line up with the edges of the port windows?

If they are scratches, then dirt is getting into your engine. If they are bands that line up with the ports, they are just marks caused by the port edges. Chamfering the sides of the ports as well as the tops and bottoms will prevent this.

[jordan83]

couple scratches and some like wider lines. none of them are deep enough to go through the nikasil and i can still see the hone marks. i assume you guys are right and i did suck some dirt. im gona go through everything and try to find a leak.

[2stroke250]

Some minor glazed lines are fine. This is because the cylinder DOES move up and down in cylinder. It is just making a pattern in your plating. Normal if you ask me. I wouldn't sweat it. Now, the wall is gouged, that's a different story.

[RedFoxCR]

This is because the cylinder DOES move up and down in cylinder.

I'm sorry? You must have meant "Piston"...

[2stroke250]

Depends how you define the cylinder  . Yes, I meant piston.

[RedFoxCR]

I have some ring-like horisontal marks in my cylinder. They're shallow, hardly noticeable, but there are too many of them. What should i do??

[2stroke250]

The first thing I would do is crack open the repair manual, get the compression psi range, and rent a compression tester. If it's in the normal range don't worry about it. If it's already off the bike, just have it rehoned and replated. It almost sounds like your getting some sand sucked in the intake somewhere. If you are, The piston ring will thinner on the intake side when removed. Next time when you clean your air filter, take some grease and smear it around the lip of the filter to seal it to the airbox.