has anyone replaced a piston in their XR 200R yet?? mine smokes like a tar heal from giving it hell last summer has metal shavings in the oil an need new rings. the rings are almost as much as a new piston so I´m looking to get a new piston kit. also I´m looking for some more performance too!! since for some reason it seems to be the only way to get XR200 performance is to replace the piston?? any suggestions will be a appreciated thanks.