Since the fuel one uses has a lot to do with how the engines run, set your timing where the points unit was to start out. Drive it some and see how it acts, and then start advancing it a few degrees at a time. You are looking for the spot where it just starts to ping/knock under a load. Find a long hill and make several trips up it in the highest gear it will pull and still keep a decent speed. If the ping goes away under full throttle and cruise rpm, this is where you leave the timing, assuming it starts without kick back. My 250 is 8 to 10 degrees advanced over factory settings, I haven't checked it for years so I don't remember just where its set.
Joe
