Skootamota engine

I just bought this engine of 1921?, the crankcase number is M and G4 matching numbers.

looks like a good engine well done

After opening the inside is in very good condition, compared to the Firefly twin the single is stronger, built to last, and oiltide.
Only one problem to solve, the pistonpin is broken at the splitpinhole in the past, they have put 2 brass discs at the ends wich is good at one end but can move around at the splitpinside of the piston.