... the 80cc, in fact there is no such cc bicycle engine in china market, we called our 47*38(bore* ... stroke) engine F80 before ,but now we correct it, because its ... 66cc(from EPA test report).2. How to caculate the engine capacity. The fomula is listed below. The volume of a ... 3.8cm(38mm) 4.7×4.7÷4×3.14×3.8=66cc3. We have rear mounted hand start engine, but not showed ...