According to the RC group here in town and the somewhat exotic workshop here in town they are a copy of the Zenoa engine. Plant called Chung Yang makes them . Popular here in town on small go carts, granny chairs, bicycles, outboard engines, etc. Cub claims a 125 hour service. Folks in the RC crowd that make their own fuel use non ethanol pump gas filtered and one of the rich oils with a pretty rich mix. Supposed to be MTDs best engine. I would imagine the unit is made and imported by MTD Southwest.