does anyone know of a way to adjust the (i think its called )pilot screw? its located under the front of the carb close to the cylinder head and very hard to reach between the carb and head.its running too rich and carbonizing up the plug and the exhaust smells very rich too. the carb was just rebuilt and valves adjusted.it starts very quickly cold and warm idels well but after running for a while it started to stall every once in a while after i would stop but restarted right up. i was thinking it might be from the plug getting carbon-ed from running rich. help!!!