Left crank case cover gasket for 50cc GY6 139QMB engines You will need to install a new crank case cover gasket every time you remove the cover to perform drive belt and kick start repairs and maintenanceDescription Left crank case cover gasket for 50cc GY6 139QMB engines. You will need to install a new crank case cover gasket every time you remove the cover to perform drive belt and kick start repairs and maintenance.It is always a good idea to have a spare crank case cover gasket handy, so why not buy two or three This left crank case cover gasket fits a wide variety of scooters and ATVs with a Chinese built 50cc GY6 139QMB engines.