The charger may not operate properly without a battery connected. It may present an extremely high voltage, or none at all. Also, 1A is barely anything, especially on a 6V system. If it were 12V, there are plenty of power supplies out there that would feed the system enough to do everything except turn the starter. I'm not aware of any 6V solutions, though undoubtedly there are some out there.
a 6v battery charger should work fine for testing lights & ignition coils if it was battery powered. I would be careful not to put it across the voltage regulator. a 1A charger may not be enough though. what is the primary coil resistance? better yet, what bike?
Tape some D baterries together as in a flahlight. 4 x 1.5 =6. Im using that on my DR250 for enough lights to pass inspection emti
Just grab a 6V lantern battery from Wally World. If you're worried about letting the magic smoke out, use an inline fuse.
This. Get a gel battery. I had one of those scooters years ago. The starter setup is really weird. It bounces the engine back and forth against compression until it makes it over TDC and fires up. Aside from the starter-generator and cooling fan, the bottom end is stock Maico motorcycle. Yours may actually be 277 cc judging from the date. The cylinder and head are unique to the scooter. The porting is designed for torque, and the piston skirt has transfer ports in it. I used a 277 scooter piston and barrel in my Maico enduro sidecar rig back then.
Generally, the Germans included the year on the serial plate as Baujahr. At the time, there were two importers. One was Cooper Motors in CA, the other was here in the Detroit area. It went by several names including Maico Motor Co, Engray, and Gray International. Owner was Nicholas Gray, and I occasionally went over to his warehouse to uncrate and assemble a bike he had sold directly. The ultimate Maico would have to be a Taifun, which was a twin 400cc road bike.