Friend has an 09 WR450F with genuine 1200km. In the last few hundred k's there is a noticeable grinding sound coming from the bottom end once the bike has warmed up but goes soon as the clutch is pulled in. Using Motul 5100 bike is like new we have pulled the clutch basket and plates out it all looks new. Replaced the clutch push rod bearing with no difference. Next step would be inside the gearbox. Perhaps the main shaft bearing that sits behind the clutch inside the case has failed? But for such a near new bike seems strange. Any suggestions welcome.