If you can run your finger nail acrossed the marks and snag them I'd say it's time for a bore / replate.
Kwakasaki
The stock 220 piston is crap and prone to breaking off the skirt, which can cause mucho $$$ to repair. Many people choose to replace it before the headache. I also ride a 220, which I bought new this summer. I got a new Wiseco to pop in it, figured I'd do it before something bad happened. Too late. The locating pin on the piston backed out and put a huge groove in the cylinder. Luckly the dealer covered it all on warrenty, but I'm still putting in a Wiseco rather than the stocker. If you hop up your bike at all you will be much more likely to break the piston as well.