1919, Opel motorized bicycle, with Z-frame shape, torpedo tank, ready to ride and complete, plaque "Adam Opel Rüsselsheim No. 4080", with 1-cylinder Opel bicycle engine engine number "4080", four-stroke, 140cc displacement, bore/stroke 57mm/55mm, power approx. 1.6hp at approx. 3000/min, top speed... more