BSA A50 Carburetor

[ramwing7]

I have a 1970 BSA A50 Royal Star rusty barn find, that's new to me.
In poring over my parts catalog I noticed that the carb in the book has a throttle stop screw.
My carb (Amal 626/66) has a plug in that position.
Does that mean my throttle stop is pre-set?
Or what?

Thanks.
Ron