"Normal" engines will start if you put the prop against compression and just flip. The Zenoah engines are different.

If you use the old technique, the magnet is past the pick-up at this point and you get no spark.

Locate the prop so that compression is at the 11 o'clock position. Then start flipping with the prop blade at about 3 o'clock and flip it almost 180 degrees.

I imagine you get a spark when the plug is out of the cylinder. Try another plug on the plug wire with the original plug still inserted, with engine compression.

You have to really flip the prop to get a spark.

Or, use an electric starter, a big one!