R REIFENG 50cc Scooter Carburetor GY6 Four Stroke with Jet Upgrades Scooter Moped ATV Carburetor with accelerator pump for many 50cc GY6 4-stroke engines QMB139. 18mm ID (Intake side), 40mm OD air filter side. Most Scooter Moped Taotao Kymco Qingqi Sunl Roketa Baja Zongshen.