Im new here and i bought another bike not to long ago. Its a 1997 RM 125 but its having a problem shifting. It goes through all 6 gears if i am riding really slow, but when i ride it fast it only goes through gears 1 and 2 and will not shift into 3rd. Does anyone know what the problem may be here? I think im going to change fluids but im not sure if that will solve my problem. Any ideas?