The variator on my 2010 Kymco Sento 50cc 4T exploded, puncturing the crankcase. Kymco lists a replacement crankcase at over $700, and a complete engine for $1500. I took a chance and ordered a complete gy6 50cc Chinese engine from ScrappyDog scooter parts for $329. The engine came 2 days later by FedEx, and it fit my Kymco perfectly. The gy6 came with a generic stator which I swapped for the Kymco stator & flywheel, and it fired up no problem.