Hi there,
Pretty sure the RPMs as far as the CDI are concerned are determined by the pick-up/magneto.
So when you switch the ignition on and off, the powervalve does a cleaning cycle. Once this cycle is complete and the engine is running the valve should return into its closed state.
If it is not, then it's possible that the powervalve wires have been inverted and the powervalve hasn't been adjusted properly. I feintly recall this being a common problem back in the day.