Just a quick update… I received the piston ring yesterday in the mail. After a few choirs, it was down to the hobby workshop and started in on the YS. I removed the motor from the Rave and stripped the YS down to its case. The sleeve has some marks / scratches that is only visible, I’ll microscope (30x eye loop) the sleeve to verify this.
The piston isn’t pretty, half of the top section, above the ring, is shattered. I believe it was from switching from rich / lean / rich condition. Once hot, the extra fuel for rich setting helped to shatter the top section of the piston. It’s the same effect as getting a crystal bowl hot…180 degrees, and then put ice cream in it. The extreme temperatures will cause to the crystal to shatter. Well, that’s my theory any ways.
I couldn’t find any FOD (Foreign Object Debris), metal shavings / chunks in the crankcase area. But just to make sure…I cleaned it out and flushed the rear bearing. It took me a few minutes to figure out how the boss pin came out, but finally got it. So now it’s a matter of inspecting everything and then reassemble the motor. Hopefully I will be able to test fly the YS tomorrow.