The OP states he has removed the float bowl screws and yet is still receiving posts about how to remove them. Amazing how people will post without reading what has already been posted.
OP - with the bowl off, and everything removed from the body that can be removed, try soaking that screw with penetrating oil over a period of several days. Like give it a squirt every other hour or so until the fluid is coming out the bottom. Rig it up in a vice so that the screw is vertical and the hole forms a pool. After the fluid is leaking out of the bottom, hit it with some heat and then a reverse drill.
One thing to consider is the carb body has a seat for the idle mixture screw. After everything is done, there is a good possibility the seat will be destroyed.
As for those cheap, horrible, awful chinese carbs. Keep in mind that most of the posters here have never had one in their hands. I have. The guts are cheap, but the castings are very good. The two that I had accepted every oem part needed to complete them. Just saying.
Oh, and about those float bowl screws, this is what you should do.........Hahahah.
Good luck.
