Originally Posted by ScOoTeR
All exhaust valves are operated by centrifugal force and depending on the setup - the assy will not move unless it is spinning pretty fast. The KX we have won't move because there are parts in the way the spin out of the way when it's running.
With the Power Valve side cover off, I could rotate it its full range of motion by hand. Now the shaft will only rotate about an 1/8 of a turn to wide open and wont return to closed. Talking with a guy at work he thinks its carbon build up, but it was opening and closing freely.