My son was riding his 03 rm . He said that when he landed a jump the bike shifted into neutral from second gear (by itself). Do you know what this could be . Thanks
My first guess would be he touched the shifter ever so slightly and doesn't realize it, after that you'd start looking at wear in the bottom end. If it starts to happen regularly I would watch his technique closely at first and then dig into the bottom end once you're certain it's actually a mechanical issue.
The engagement dogs might be slightly worn in your tranny allowing it to slip out of gear. Take Chili's advice before you go after the tranny. Good luck dude............
I would also watch him closely on the track before looking into the tranny....That said , my friends son had an 03-RM 125 , and within the first 25 hours most of the gears were shot.....