ticking, knocking noise in 400ex motor

[Knips178]

I just got done helping my brother take the head off of his 99 400ex because of a ticking/knocking noise. It sounded like a sticking valve and sure enough when I looked at the valves while manually rotating the engine the exhaust valve was sticking popping back into place. The valve guide was bad apparently and there was tons of carbon buildup in the combustion chamber!
Now my 400ex has a similar ticking/knocking sound. Is this a common problem with 400ex's? Carbon buildup in the combustion chamber and bad valve guides? or are we just lucky?
Also, what is the best thing to use to clean the engines combustion chamber out, without totally disassembling the engine?

[Greg Z]

just bring it to the dealership and when the fix it watch them its good like that

[quadcustoms]

might replace the timing chain, cheap fix first place to start if the valve clearance is good