Originally Posted by
SrTelemaster150
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.
Dan, what you say sounds very convincing. I can assure, however, that when in idle the barrel does not rotate as this is prevented by the servo provided with the linkage is appropriate. The barrel can still move back and forth in the carburettor body as the engine vibrates. In actual operation this may or may not have effect on changing idle mixture. In some installations it is like if you screw the LS screw in and out.
Further, I think there is a reason why my OS and Laser engines all have the barrel spring. And generally speaking, all the recent Saitos have the spring.
I do not want to make this a big thing so this is just how I see the matter. I am happy to stand corrected if I am wrong.
-Artto