Worn rings
 

Can anyone tell me what it sounds like if your rings are worn??

If you want a good general idea of the shape the rings are in pull the pipe and inspect the piston and rings through the exhaust port. If there is brown blow by residue on the piston skirt it's time to tear down the top end. If the rings ever got worn enough to make a noise it would probably be too late for a minor top end rebuild.