It sounds as if it is flooding. Most likely either the float is not moving completely freely on its pivot, or there is now dirt lodged between the needle and seat. I suggest you try the easiest cure first. Turn off fuel, remove float bowl, disconnect fuel hose at carburetor end, and blast some carburetor cleaner through the tubular connection to the carburetor where the fuel hose normally attaches. Then reinstall float bowl, reconnect fuel hose, and see if the problem is fixed. If it is just a bit of dirt under the needle, it should be.
