Since I have examples of both the "standard" & optional DA-220 carburetors in question, I went out to the garage & checked. The "standard" 11mm carburetor for the FA-220 Is exactly the same as the FA-180 right down to the throttle barrel spring. It even has the same part number. It will spring back slightly from a closed position when released.
The 12mm "big bore" carburetor for the FA-220 does not appear to have the throttle barrel spring as it does not spring back from a closed position.
When the throttle is connected to a servo, whether or not it has a spring is a moot point as the throttle servo will hold the throttle barrel at any given position. Only if there was severe wear on the screw or throttle positioning groove in the throttle barrel could it have an affect on idle.
Last edited by SrTelemaster150; 08-02-2014 at 08:45 AM.