Now go to the throttle arm on the carb. Unhook it and move the arm until the opening in the intake is half opened. Will the throttle arm and the pushrod now make a 90 degree angle? If it does, adjust the length of the pushrod to connect to the arm where they will have that 90degree angle.

If it does not, then loosen the screw holding the throttle arm and move that arm to the 90degree position. Tighten the arm and adjust the pushrod.

You now have the rigging setup so the servo will rotate the throttle equally in either direction.

Now........