From : http://www.ch-ignitions.com/index.html

4. It is normal to hear a spark fire inside the module case if you trigger the ignition with the spark plug wire removed and not grounded. Do not do this unnecessarily. If you get a double spark once as the magnet approaches. and once when it leaves the pulse switch, then the battery is bad or needs recharging.
Empathizes added.

I was very cautious and asked a bunch of questions before ordering and a few during install...Terry (CH) was quite helpful.

Being you have a Zenoah, check with RCIGN, he builds and installs them on customer engines. Many favorable comments regards his work. Wish I had the 'fun shoot out of comments' between Terry and Ralph. If I remember correctly bottom line was similar price with RCIGN doing the installation for his customers.