Since I don't know how to put sound into a picture, here is a short and absolutely unspectacular and unedited video with some Hirth 4-stroke music.
Please forgive the botched loop at the beginning.
Later you can see the peneumatic fuel measurement and the manual fuel pump in action.
400MB warning, so don't use your mobile phone to stream this one.
https://www.classics-hangar.de/vorschau ... _kl25d.mp4