Originally Posted by
Firewalkerd1
I came up with a 20cc side carb and exhaust at a local swap meet. It is marked XZY on the front case. ...
Google up "XYZ" and see if what you have fits one of the many pictures of XYZ engines. Several variants including side carb and exhaust. Could be what you have. Good luck, it sounds like they were of the "Early Chinese" offerings.