So, I made it to the final assembling of frame and wheels.
Every bolt is checked, fastened and secured. Most bolts are replaced by stainless ones (except all motor bolts and nuts, front and rear brake bolts), chain is mounted, oil-pressure switch and idle switch are installed, generator is placed aaaand....
I found this retro bicycle chain protector in my local store, which I thought could be a good option for my bike with some minor changes.
The price of 12 $ just underlined my plans.
So here it is:
It's quite a straight fit
To have a lighter and sportier look, I shortened it like this
There are only the appropriate mountings to manufacture, but that's a minor problem...