4X, The mechanism will rotate approx 90 Degrees when it does actuate... I don't remember the actual RPM, but I know it's up there (about 5,500 RPM I think).
There is an extensive explaination of the different power valve configurations here:
The LT500 uses the SAEC setup. You may be in need of adjustment if yours isn't working.
They do have a tendancy to gum up if you're not using a really good quality oil.
This may require disassembly and a good cleaning to make it work the way it should.
Hope this helps.