My son has told me that his 2005 CR85 has not allowed him to shift up, he even pulled off the track to see if he could shift through the gears by hand and said he could not. Each time this happens I hop on and see if I can shift and have yet to experience this. I keep the bottom end oil changed never any metal and have recently installed a new clutch but for me, it has shifted fine? Any experience with intermittent shifting problems with this bike?? Thanks!