2008 Yamaha Raptor 250SE / 250SE2 Factory Service Manual, Page 151Get this manual
CYLINDER AND PISTON
CHECKING THE PISTON PIN 1Check: Piston pin Blue discolorationgroovesReplace the piston pin and then check the lubrication system2Measure: Piston pin outside diameter Out of specificationReplace the piston pinPiston pin outside diameter 16.99117.000 mm (0.66890.6693 in) Limit 16.971 mm (0.6681 in)