The idle mix screws should be set about 1 1/4 turns out from lightly seated. After that adjust each the same to achieve the highest idle or vacuum . Then go back and adjust the idle speed screw down. This is best down in reverse with a trusted friend on the brakes and the parking brake set. You can adust the idle mix screws once more to get the highest idle then readjust the speed screw. look at the sight plug, is the fuel level still just below middle? It should be. If its high you may still get black smoke at idle at times. I like to set mine a little low an worry about running out of fuel at the top end later. Regarding the bog, it can be the accelerator pump or the secondaries opening too early. Either put a stiffer spring in or wire the sec shut. If the bog still occurs its the pump. A black cloud when you hammer it means too much fuel. Either the wrong cam or the wrong shooters. get a book, I have
" how to tune & modify carburetor performance" by motorbooks int and it has saved me many times on all kinds of carbs. If you lose the bog with a stiffer spring or secondaries wired shut, the spring you have is too loose and needs to be stiffer. Too stiff will give you a flat feeling. then you play around from there. your parts store or a place like summit will sell you an assortment pack of color coded springs that will take care of the vac sec. Otherwise, the pump cams are color coded too, an you can buy a kit or seperate