I am having problems with my new 400EX and the dealer is at a loss. The valves were tapping loudly when warm so I adjusted them to spec at 20 hrs they were tight (which was to be expected) The problem has continued to get worse the more hours I put on the quad. I have checked the valves warm and there is .07in on the intake and .08in on the exhaust when hot but they reurn back to specs after cooling overnight. Anybody ever seen this on a 400EX.