My bike ('87 XR600) hates loose, sandy trails we have in the Mojave desert....it shakes it head; does not matter how fast or slow I go; it's more than just a little annoying, it wears me out. I have just finished overhauling most of the bike....new wheel bearings, steering stem bearings, Eibach 12.5kg rear spring, Eibach .47 fork springs. I have varied fork oil, tried 5wt, 10wt & ATF (like 5wt best), I have played with race sag, between 3.5" & 4.5". No change. I have not played with varying the fork tubes in the triple tree; they are at the stock setting - about 3/8" above the triple tree. I am running a half worn Dunlop 739FA front tire. Maybe a different front tire would help? Others have said that all the XR600's do this and that you really need a steering damper to fix it. Ideas, suggestions?!?!??! Thanks.