Need help::What is this front mount motor...?

[whizzer kid]

A buddy owns this and we want to redo it. Curious of the maker of it and history. Has a serial # and that’s it . Carb is a tillotson.
Very small spark plug and a schwinn style expander brake lever .
Thanks
for any help
Eric

 

[whizzer kid]

Pics

 

[whizzer kid]

Thanks bricycle !!

 

[Lynchwrench]

Definitely nothing like a four stroke..

 

[bricycle]

Duncan Motor