Just bought a used 2010 yz450f, so i dont have much history on the bike. It is jerking, more so in fifth gear, but in 3rd and fourth as well. Also its more noticeable at high rpm. Its not spuddering, like it would with fuel or spark problems. More like clutch or transmission. The engine revs up, and loses power to wheels. I do not hear any grinding or skipping when this happens, its more like if the clutch were engaging and disengaging momentarily. Thought i would jump on TT and fish for ideas! Remember, i jus bought the bike yesterday(of course it ran fine on the short test drive) so i have no history on the bike. Any ideas or suggestions would be appreciated! So far i have cleaned air filter, changed oil(amsoil 10w40 synthetic) and tried adjusting clutch cable. I also put in fresh premium fuel with a splash of sea foam.