J tab, What helps the carb to work better with these engines.....sorry if you are already aware of this.....the choke area is too large for these engines. Adjust the full throttle on your transmitter so that the carb butterfly opens only 3/4 open then retune. I have mine adjusted less than that! 5/8 ths open. I barley loose any power and the midrange is quite a bit better with much better transition......really. Recall I have the 215's. If yours is a 250 3/4 might be better than my setting. I run my ignition at a regulated 5.5v. I think your plane is really cool. I like those vintage racers. -Tom