2008 Yamaha Raptor 250SE / 250SE2 Factory Service Manual, Page 266Get this manual
REAR SHOCK ABSORBER, SWINGARM AND DRIVE CHAIN
6Check: drive sprocket driven sprocket More than 14 tooth wearReplace the drive chain sprockets as setBent teeth# "# Replace the drive chain sprockets as setCorrect Drive chain roller Drive chain sprocket
EBS00497