RE: husquarvna 22.5cc
Lawndarts, the engine would make a nice conversion. Put EI on it and save the weight of the flywheel and mag. You want to leave the spring on the shaft but disconnect the hook and clip it off. Your servo will hold the throttle position. The spring acts kind of like a spacer so you want to have it there for that only. Are you saying there is only one needle? You want a 9mm carb or so on it with a high and low needle. One line is fine. You will vent the tank anyway.
Tim