Think I found my starting problem was putting a kit in my Kingston l4 and the flapper was put in upside down still need to go get a couple small cotter pins for the butterfly,, now can someone tell me just what the brass flapper is for maybe it will start after I get the carb back in
Here is a thread that talks about the flapper, they call it an "air valve":
Here's another thread with a good exploded view of the carb (final version at the bottom of the thread):
The flapper is an enriching devise. At low speeds the flap is closed forcing the richer fuel/air through the small passage at the needle valve.