2LA Big Bore Kit GY6 50cc to 80cc Scooter Moped 139 QMB 139QMB Cylinder Piston CK14 1x Cylinder Block. 1x Piston. 1x Complete Ring Set. 2x Circlips. 1x Piston Pin. 2x Head Gasket Set. Change from 50cc (39mm*41.1mm) to 80cc (47mm*53.2mm). Works with stock Cylinder head.