Have a XR600 with new cam (HotCam) but saw that the valve lash become bigger all the time. But only on one valve/rocker. So I put away the top head cover and saw that the rocker been "eaten" up. I didn´t change the rockers when I changed cam (said it wasn´t nessesary). What could have caused the dammage? So I won't destroy the new I should install..