I'm giving my '99 WR400 (YZ'd) a good once over this year. New plastic, light, handgaurds, Big Gun exhaust system, etc. I'm going to do the valves and I am wondering if I should do a top end also. To do the valves, I will not take the engine out, but if it needs a top end, I might as well take it all the way out. (I will do my own valves, but take it in for a top end). I know 4 strokes don't need them hardly as much as a two, but it has been 5 years now. Has anyone needed to do this yet on their 400?