Limitation for Kymco and China scooters Replacement crankshaft in standard quality for 50/90 cc 4-stroke engines (GY6 50, 139QMB / QMA). The crankshaft comes fully pre-pressed with crankshaft bearings and connecting rods. In GY6 engines 2 different versions already installed at the factory. They differ only in the oil pump drive gear on the right side. The old version is installed in almost all scooters and has a gear with 16 teeth. The new version has 22 teeth and is used for example in new Rex models. Please count the wheel teeth for driving the oil pump for safety. In the product photo the tools in question are again mapped in detail.