If the barrel is unmarked, then you will most likely just need new rings. The plating on the cylinder is rock-hard, and highly unlikely to be worn.
Although not a definitive way to tell, as every rider/condtion is different, what mileage has the motor covered (a) in total, and (b) since you've owned it? This will give a loose indication as to whether just rings, or pistons and rings will be needed.
At the end of the day though, you won't really know until you pull the barrels off and have a measure up.
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Andy.
NSR-WORLD.COM
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