I also have a little wartime charger with a JAP engine you may have noticed it. Its been stood in my shed for years and i guess its nbot been started in decades, put petrol in it the iother day and it fired first pull. After a quick clean of the brushes it pushed out 9 amps with variable voltage between 10 and 40 it can charge all our batteries.
We have had trouble starting after ten runs.
This little motor is started plugged in and the engine fires instantly every time 🙂