I just saw your other post, as you have a single cylinder engine, you only require a single spark every other revolution, the other spark is called a waste spark. It is a problem mechanically to stop this waste spark as it requires gearing to stop it, so manufacturers just let the waste spark occour as in a petrol engine it doesnt cause a problem.
In my hydrogen engine i had to remove this wast spark and had to build a gearbox to deal with this.
Since the ignition module works using a hall sensor it lends itself quite readily to being used as a tacho, if you would like i could look into making an ignition unit with a built in tacho that has an LCD display with the RPM displayed.