Left - I've never had a cat, but I'm thinking this is cat food... and I'm also thinking it's courtesy of some mouse.

Below Left - Horizontal head showing dirt in the combustion chamber that was locking up the engine. (note shadow from the build up on the left, which was on the bottom, in-bike position) Also notice buggered-up spark plug hole.

Below Right - Horizontal cylinder. Yuck.

Bottom - Vertical cylinder wasn't exactly spotless either! (Yes, it's missing a stud)