Got a Brillelli 46 that has lost 5 or 600 rpm. When I crank it over by hand there is a "clicking" at TDC. After pulling the plug and looking in I see quite a bit of carbon buildup.

I'd like to pull the jug and see about cleaning her out. Having never done that, I'd appreciate a few tips.
Also, will I need to replace the rings if I do take the piston out?

Cheers,

Andrew.