I re-ring, change gaskets and clean/rebuild carb every season. Cheap insurance in my mind. When you feel a loss of compression you will obviously open her up. If you see major scoring/scratches in the cylinder then you'll need a new head kit, if there isn't anything majorly scratched you can re-ring.... I'm waiting on a couple of rings right now for my 27.2cc, the cylinder shows some scoring but should be fine. I'll post up a pic of the head I'm working on so you have better idea.