Just to let u all know I finally made a runner. And broke the crankshaft and fixed it again.
The first one was 2 part fixed with superglue??? My four year old loved the engine so much it did not last an hour. I then made the replacement by turning it out of as solid piece in the four jaw chuck--seems fine so far.

FLywheel is 16mm diam and 4.5 wide.(forgot to put somthing for scale.)
Gerhard