My brother has just got himself a 00 model rmx250 after a few laps at our favourite track he said the bike, when hitting med-large braking bumps and accl bumps would jump out of gear. Didn't matter what gear he was in either. Any help would be great. Thanks guys.
Does this happen in neutral or in any certain gear. My sons 06 RM85 done the same thing but only in 1st gear at 3/4-full throttle. After pulling down the top end I found it was a gummed up exhaust valve due to previous owner let the drain hoses clog. Try having a look at that and opening your exhaust valve covers and giving that a good clean. Hope that helps you.