So I was riding my Yz 426 on Saturday at sand mountain out side of reno nv. And after a couple of runs up some dunes I let of the throttle and I felt on power. As I pulled out of the super blow I let off and the bike felt like the rear brakes where on. I stoped and shut the bike off and let it cool for awhile and then tried to restart it and the kick stat was rock solid. So I waited awhile longer while my buddy's where riding in the super bowl. Tried it agin and it turned ofer for about three kicks. And rock hard agin. Towed it back and now it sits waiting to be torn apart. Any ideas what could of happened. And do I rebuild the whole thing crank,hot cams,valves,and big bore kit or no big bore ki? It curantly has the decompression kit on it so it was easy to start. Any advise would be great.