1) Model: 139QMB (for 50cc) 2) Engine type: single cylinder, air-cooled, 4-stroke 3) Bore x ... x 41.4mm 4) Displ Specifications:Model: 139QMB (for 50cc)Engine type: single cylinder, air-cooled, 4-strokeBore x stroke: 39 ... /40Lubricating system: pressure splashClutch type: automatic, centrifugalIgnition: CDI EEC Scooter Engine