Odd Ring Wear on top surface

[VFR750]

Here is another oddity on my search for a leak free engine.

Here is a comparison of upper compression rings. One looks good, the other has a trench worn in it.



What is so odd is the slight trench worn into the Goetze ring. You can feel it as well as easily see it. The trench is deepest 180 degrees from the split, and gradually disappears near the split.

ALL compression rings show this wear pattern, too. Upper and lower compression ring. Weird.

The 32 year old rings that came out of the engine don't have this wear. They look as I would expect.

The JE Piston designed the upper groove with a 0.0015" side gap. This is their standard. It is on their website as well as the paperwork that come with them.

Porsche calls out 0.0027"-0.004"

I just looks odd to me.