uneven piston ring wear

[Michael S]

I'm in the process of replacing rings on my 2009 200xc and I noticed the old one (on the top in the photo) is worn down a lot more on one side compared to the other side. Is this normal? if not what could be the issue?  

[mog]

Out of round barrel

[Michael S]

4 minutes ago, mog said:

Out of round barrel

what's that mean?

[M A T R]

what's that mean?

Your cylinder could be worn out.

[Michael S]

How can I found out for sure if that's what it is?

[GasItandCrash]

Can't be any more out of round than the .006" Nikasil?  Or is this a steel sleeved engine?

 

[Michael S]

33 minutes ago, GasitandCrash said:

Can't be any more out of round than the .006" Nikasil?  Or is this a steel sleeved engine?

 

I beleive it is Nikasil, I don't know a thing about cylinders, if it is worn how would this be fixed?

[markit]

Likely from running rings wwwwwwwwaaaaaaaaaaay past spec [emoji15][emoji849]

If you cant, take your cylinder to a shop/machine shop and have it measured.

 

[Brent72]

You could measure the diameter of the bore across different directions (along parallel with the wrist pin, and then perpendicular to the wrist pin...) and see how those dimensions compare.  If all the measurements across are equal, then the bore is round.  If those measurements are different, then the bore is out of round, or oval shaped.  You can use an inside micrometer to measure this.  Example... amazon...

I would think that as the engine fires and the piston is pushing down on the connecting rod which is offset towards the front of the engine during the power stroke, that this causes the piston to push harder against the rear face of the bore.  Easier to explain with a picture, which I don't have.  I'm curious if the worn out side of the ring was positioned towards the rear of the engine.  This theory may suggest that the bore is ok, but the ring has just not been replaced in a very long time.

[Brent72]

I think my theory is correct... found a reference here...

[Brent72]

I think an out of round bore would create two thin spots on the ring, on opposite sides.   The photo at the top has wear on only one side.

[yz250f 78]

maybe could be a crank issue.

some play in the clearances of the rod that is forcing the piston to push to one side

[markit]

As above the cylinder may need some attention but the top ring wear is mostly due to lack of service and a out of round piston. If it was a cylinder problem the second ring would show similar wear.

[markit]

maybe could be a crank issue.

some play in the clearances of the rod that is forcing the piston to push to one side

I'm fairly sure that with the amount of wear the piston has piston slap had to be very noticeable add in crank wear I just don't see anyone riding that much less running it for any time. Rings wear like that when ran well past a acceptable time (60ish hrs). But with the situation I would recommend the crank b checked. [emoji106]

[wchefd]

Have a pic of the cylinder? If your cylinder is good. Get some new rings, check the end gaps throughout your bore, install, ride. Check again in 10 hours and measure the rings with a micrometer.

[bikedude987]

How many hours on that piston?  I would guess (if you weren't sucking dirt) over 200!

[Michael S]

I think my dad has a micrometer, I'll measure the cylinder after school.

[Michael S]

here's some photos of the cylinder, still pretty new to this, anything noticeably wrong or anything that needs attention? I measured the the inside of the cylinder with a micrometer and I took the measurements a few different ways and all the measurements were a bit different but within .02 mm of each other both sideways across the cylinder and front to back along the cylinder. 

[wchefd]

Not bad for the ring wear. Lightly hone or deglaze with a scouring pad. Rub around the bore, not up and down. Wipe down the inside, lightly coat with some oil, and your good. Check and change your rings more often. You got lucky this time.

[Michael S]

6 minutes ago, wchefd said:

Not bad for the ring wear. Lightly hone or deglaze with a scouring pad. Rub around the bore, not up and down. Wipe down the inside, lightly coat with some oil, and your good. Check and change your rings more often. You got lucky this time.

should a scotch brite pad suffice as a scouring pad? The PO neglected this bike and it was listed fairly cheap and I thought it would be a good project to learn how to repair and do proper maintenance on