Im pretty sure i know the asnwer to these but it cant help to check.. 1 what (if any) are the signs when a top end is in need or close to being rebuilt? and if the bike is running fine and is overdue, what could happen 2 am i right in saying you can wear out 2 rings in the time a piston wears out? 3 what are the signs of a worn ring 4 what are the signs of a worn piston 5 if a cylinder has been bored out, the piston is made bigger to accomodate, not the ring made bigger? so for eg my yz125, if it was still stock the piston diamter should be 54mm. if it was lets say 56mm it would be bored out? 6. does the cylinder walls wear out from normal use and would need to be re-bored/plated? or only when dirt has got in?