Hello I'm new to the forum and i bought a '00 400ex yesterday and put about 2 hours on it today. While riding i noticed a ticking that definately sounds like valves. I'm under the impression valve noise is common on 400ex's. My bike doesnt have any signs of needing a valve adjustment. It starts right up and has good power. My buddy with a 660 was only beating me by about a quad length or less and the drag was long enough for me to top out 4th.
You don't normally hear the valves ticking unless they are super loose (15 to 20 thousandths clearence). Most noise comes from a worn cam chain. On a high milage motor that recieved minimal maintenance, you might hear piston slap. Neither will have a huge effect performance, but if the engine's deficiencies are corrected you will have a noticable performance improvement.
Valve ticking help?
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