There has been alot of concern about valve addjustment. Here is a hint when setting valves the motor must be cold. Let the bike set for at least 10 hours.On 250 and 300 EX use two feeler gauges. One on each side. Then set the valves at the same time. If you do not the rocker arm will rock to one side. Then when you set the other side the valves will be to tight you can not get a true reading unless you do both at the same time. On 400ex this does not apply. If you pass top dead center on the 400ex do not turn the crank back this will engauge the compression release and give the wrong exhaust settings. Just some hints.