Gary Conley never really put much information out there on the Conley Precision engines.
The enclosed Manual for the engine might give you a bit more information, such as displacement which is about 3 cubic inches, or 50cc.
Also the enclosed Popular Mechanics Magazine article might give some more detail on them.
Click here to open the PDF-file of Conley Engine Manual
Click here to open the PDF-file of the Conley PM94 article