I pulled the rings off on my '00 Katana GSX600f, & they don't have any markings. Just totally plain/smooth. Sizes line up w/new ones, but no id marks. Does this sound like oem from factory or someone used cheap/incorrect parts?

Bike has been apart, but I couldn't tell if the cylinder had been off or not. I got it as a project that would need rings. Compression test confirmed it. Has about 10k miles. My theory is: a rusting fuel tank leaned out the mixture until it overheated & had compression issue. Tank is well rusted, carb jets main were def clogged.

New rings are marked 'R' and 'RN' & while I'm certain they're correct for the motor, I'm concerned about fit after seeing what was in there.

Any thoughts are appreciated!
Thanks

The top/first ring is R and 2nd (from top) is RN
Still curious about the unmarked rings I took off. If genuine Suzuki parts has markings, then what the heck was in there? I measured the thickness & they matched the new ones, but w/no markings it'd be tough to determine top from bottom.

Maybe this was the problem all along?🤷‍♂️

I can't say what the factory ring pack looks like.
Some rings have no markings, but orientation is determined by the profile of the rings.
Rings that have no markings and are symmetrical can go either way. This is usually just the top ring.

The second ring has a scraper function, if installed upside down, it will cause oil consumption.

Below are  images of ring profiles.

So after sometime I've been trying to get it to start with no luck. A compression test revealed that dry: all cylinders are about 50-55 psi. Wet it jumps to 120, but my gauge broke after #3, so I still have to check #4, but I think I know the results.

Things to check on teardown:
Head bolt torque
Missing O-rings on the head gasket
Ring orientation
Cylinder bore
Ring direction (my leading suspect, since all cylinders tested same psi)

Am I missing anything???