Er, what?
There is no "Window of movement". The motion sensors are accelerometers, they detect acceleration of the control on 3 axes. Obviously, if you wang it about as fast as you can you will end-stop the accelerometers straight away and find it does appear to have a restricted range.
The ADXL330 accelerometers used in the Wiimote have an effective range of +/- 3g, so it doesn't take much to end-stop them.
If, however, you use smooth movements you will find the response more realistic.
So more Obi-Wanesque smooth moves and less frantic wasp-swatting is what is needed.....