-Start by removing the exhaust pipe. There's springs at the engine and at the muffler itself as well as a spring hidden behind the pipe on the clutch side of the engine. The easiest way to pull these is to get some nice hand vise grip pliers, clamp them down on the spring below the hook part, then pull the hook up and out of the loop. The one's on the muffler are different than the ones at the engine so try not to mix them up. Once these are gone the pipe will remove without any difficulty but there will be a round large gasket puck at either end, don't lose those either.
-Get a 1\2" socket and a ratchet (or a 1\2" wrench) and if you look where the steering post comes down from the handlebars you'll see a plastic box with two nuts on either side. Remove the nuts and carefully pry the box cover off. Mine was PRESSED onto the damn bolts and wouldn't come off, one side broke a bit where the bolt came through. Be careful you don't break either (or at least one) side if possible. If yours are tight, once it's out widen the holes slightly with a drill or knife.
-Now you will see the servo motor with both cables attached to it's tumbler. Take a permanent marker and colour the cable that is closest to the front and then put a dot on the servo tumbler closest to the front, just so you don't mix up which cable goes on first. Then turn the motor (if facing it from the front of the sled) counter-clockwise to undo the pressure on the cables. They will slack up and you can slide them out the side of the wheel one at a time.
-Now the cables tubes will be attached to the servo housing, there's a metal clip that locks them in just pop it off with a screwdriver but don't lose it, then pull the cables straight down and they will unplug from it. If you look down you'll see where the cables can be adjusted, there will be a black plastic guide that holds both cables side by side, just unsnap it from the cables and put it somewhere safe.
-Now that everything is free'd up you can pop out one of the APV's. They are secured by 2 10mm bolts. Do them one at a time so you have a reference point in case you don't remember how to re-install one. Undo the bolts and carefully pull it out of the engine, there is several peices and 2 gaskets. Not to mention the valve IS spring loaded so it will want to "pop up" on you when undone, however nothing will fall apart as it's all attached in one big run, only the gaskets are loose unless the bolts are through them.
-I cleaned mine with an exacto knife and throttle body cleaner, brake cleaner would probably work too, or better yet carb cleaner. Scrub them good and use a blade to remove hard carbon deposits.
-Re-installation is reverse of removal. Here's a pic with instructions as well:
My valves were in awesome shape with only mild crud on them, the amsoil interceptor is definitely doing it's job because this is the first time I yanked those valves in 2500mi of use. Also while the pipe is off it's a great time to install fresh and properly gapped plugs. hth