ENGINE WILL UNEXPECTEDLY STALL WHEN STARTING TO DRIVE OR SHIFTING TO UP OR DOWN. IT HAS CAUSED ME TO FALL THREE TIMES. THE FIRST TIME IT HAPPENED THE FIRST WEEK I TOOK DELIVERY WHILE DRIVING UP MY DRIVEWAY THE BIKE FELL AND LANDED ON A ROCK. SECOND TIME WHILE LEAVING ON A TRIP FROM MY DRIVEWAY, IT STALL ON TAKE OFF AND FELL IN THE ROAD. NEITHER TIME DID I GET HURT BUT I COULD HAVE FALLING IN THE STREET. THE THIRD I WAS TURNING INTO A SIDE STREET THE BIKE STALLED WHEN I DOWN SHIFTED, THE DIKE FELL AND I WENT OVER THE HANDLE BARS AND LANDED ON MY SHOULDER ON THE PAVEMENT AND HURT MY SHOULDER AND ELBOW. IT HAS ALSO STALLED OTHER TIMES WITHOUT FALLING. THE FALLS HAVE HAPPENED WHILE THE BIKE WAS MOVING SLOWLY.