If the rotary carb has two inlets your your options are limited. They make a type of induction system where the mixture charge is enveloped by plain air. You can't put a regular carb on those. Well, actually you can but it will run poorly. The idle mixture may be ajustable by a needle in the barrel of the rotary part of the carb. It will be in the middle of the butterfly. IT may not help much. The over all mixture can be ajusted by altering pop off lever height. I have never goteen one to run to my satisfaction after hours of fiddling around. Sorry.

Post a picture here, so we can see what you have. Lots of folks, including me, refuse to have anything to do with facebook; or most of the modern hand held dialed in world. But that is another conversation.