Hello Frank
I would put it in the engine sauna and boil it up to get that burnt on oil/carbon off. If there is no metal to metal contact from a distorted liner/piston , then something is there that shouldn't be and has to go...
bye Gerald
I would beware Randy's admonition in his fuel post (pinned to the top of the forum and required reading - or should be). When you clean off all the carbon, there's a really good chance that you will have no compression left.
There may be something else wrong, like distorted cylinder from a crash, improper muffler installation, uneven head bolt torque, etc (because it could be a bunch of reasons), but most are insoluble without replacement parts.
I would just run it a while, see if anything changes. If it vibrates violently, er, more violently than normal, then look for a bent crank, bent conrod, uneven wear in cylinder bore carbon, etc, and replace the part/parts that are damaged.
Brett