1) In cleaning the carb on my 1977 dt100,  I find that this port seems to be clogged  (see picture in link).   I cannot blow through it or spray carb cleaner through it.  (I did an ultrasonic clean)  in watching u tube videos, no one seems to do anything with this port.  what is it and what is its purpose 

drive.google.com/file/d/1tOPSxEhMqbc0FuK.../view?usp=share_link

2) Also,  I cannot find an initial setting for the throttle adjusting screw.  The manual just says to start the bike and adust for good running - target 1300 RPM.   what is a good initial setting for this?  example,  fully closed, 1 turn out ?????  Seemed to be all the way in at carb disassembly.



 

That's the starting enrichener (choke) tube. Draws fuel from well in float bowl. Should flow very freely with choke plunger open. Also check the teeny (non-removable) starter jet in bottom of float bowl that allows fuel into the well the tube fits into.

Air screw rule of thumb is 1.5 turns open or whatever manual says. Throttle stop screw has no "setting". Screw it in until the slide raises slightly and then adjust speed after bike is running.

Makes sense. Thanks for the quick reply