oil pump assembly for 16 tooth crankshaft for GY6 50cc 139QMB/QMA BT10007

139QMB/QMA engines currently have 2 crank variations factory-fitted. The differences are solely in the oil pump drive gear. The crank can be kitted with either 16 or 22 teeth. This also means two different oil pumps are used. The item pictured is the 16 tooth version.