The idea behind this style of compression release is to drop the compression ratio. If the engine turns slow enough, the CR is effectively infinite on the right side; zero on the left. The starter motor turns the engine a minimum of 300RPM; hopefully as high as 800RPM. I have to use a little higher math to actually deduce the CR at the various speeds. A more elegant release is in the style of the 500 singles: lifting the exhaust valve off its seat during the compression stroke. Very large displacement motors may have solenoids holding the exhausr valves open as long as the starter button is engaged.