Seems to me that there are several issues going on that may be in addition to a slightly aggressive needle setting. If I,am not mistaken that fuel has no caster at all. A small percentage of caster in the oil mix will do wonders. Also you are using a very hot four stroke plug. Remember plug heat is the one easy method we have of controling the ignition timing in our engines. A hot plug will advance the timing slightly and a cold one will retard. Retarded timing = a little easier starting, slightly less power and a lot cooler running. Suggest you try the McCoy MC-9 (not the MC-059 thats a hot one) a genuine cold plug and run don,t walk to the LHS get some fuel with a little caster in it or a bottle of caster and spike some in the stuff you are running. Avoid like the plague all four stroke plugs that are very hot by design.

John