...Most likely it is magneto ignition (no battery). some of the EC built bikes had a peculiar magneto/flywheel arrangement that made removing the flywheel difficult resulting is breakage of parts. If it does not come off easy and there is access to the ignition points thru or from behind the flywheel then just rig it up to run off of a battery and car coil. Otherwise the retaining nut and or flywheel may be damaged in process of removal. Just tread easy on the removal.

Neat find, Gerd! I think that is really great you are helping the young fellow fix it up.
Enjoy!