... : single cylinder, air-cooled, 4-stroke 3) Bore x stroke: 39.0 x 41.4mm 4) Displ Specifications:Model: 139QMB (for ... )Engine type: single cylinder, air-cooled, 4-strokeBore x stroke: 39.0 x 41.4mmDisplacement: 49.5ccCompression ratio: 10.5:1Max ... grade: SAE15W/40Lubricating system: pressure splashClutch type: automatic, centrifugalIgnition: CDI EEC Scooter Engine