I have a 2000 honda 400ex and after 2 years of beating on it, last summer the valves started ticking much more than usual. I should have adjusted the valves then but never gotten around to it but it ran fine and I have only put about 20 hours on it since then. Well the other day I was riding Wide open in a field and my spark plug unthreaded itself and fell out. Since then it really hasn't been right. It doesn't like to idle and starts hard, when idling it makes a leaking noise and it still ticks loudly. It hasn't lost any power or acceleration but its definatly not right. I was wondering what people on hear suggest I do, I was planning on taking off the head cover and head and checking everything out and replace the valve seals and head gasket and maybe timing chain. Or Whatever else is worn. Then i'll Adjust the valves to specs. I'm going to silver lake memorail day weekend and don't want to risk running it like this so I got to get working on it soon. The motor is all stock never been touch, I run maxima syn. blend 10w40, and only mods is full exhaust, K&N and 55 main jet. Somebody please point me in the right direction.