^ that was sort of unclear. The "cover thingy" I am referring to is the spring-loaded tab (with the hole in it) that restricts the airflow when the choke cable pulls it over the air inlet in the carb. On cable choke SHAs, this never fully closes and blocks about 1/4 of the intake.
Assuming you do have a cable choke carb, here is how increase the flow (you need a dremel or equivalent)
To grind it down, engage and then release the choke lever on the handle bars. Then carefully remove the carb from the intake (no need to disconnect any cables) and pull off the air filter. You will see that the tab is blocking the air inlet. Use a sharpie to mark the corner of the tab that is blocking the inlet, and grand it down in the shape of the inlet. Done.