RE: FA-125a - Throttle Stop

Is the screw circled in yellow the “Throttle Stop - Adjustment screw” or just the “Throttle Barrel Assembly - Retention Screw”?

On my Saito FA-125a , it’s pretty hard for the servo to completely close the carb. to kill the engine. At the field, it takes multiple tries with the kill switch, to get it to stop.

I have the radio’s throttle servo travel programmed as far as possible without it binding. Even when the throttle linkage is completely disconnected, and I press hard on the carb's black plastic throttle lever, I can’t close it completely.

If it is indeed a “Throttle Stop Adjustment Screw” I just need to verify that with someone who knows these engines well. If it’s not (and turns out to be a retention screw), and I back it off some, it will eventually vibrate looser, and the barrel will pop out in flight.

Also, if IT IS only a retention screw that must be left tight, does anyone know if the depth of the slot in the throttle barrel tapers-off at the end? If it does, I should be able to remove the screw and add another small washer. After tightening it back, the net effect will be that the barrel can travel just a bit farther … which would be perfect.

I will have to remove the engine from my Edge 540 to get at that screw, so I wanted to check with you guys first (before I went to all that trouble for nothing).