A friend of mine has a 2000 XC 500 SP and to clean the valves on it we just unbolt them where they attatch to the engine (2 bolts) and slide them out, then scratch all the carbon from them using carb cleaner and steel wool or a knife. Just be careful to not scratch up the valve.
"Might Be Crazy But I Ain't Dumb" - Cooter

"Might Be Crazy But I Ain't Dumb" - Cooter