Hoping this doesn't come under jetting...

I have noticed my MC21 is slow to return to idle when revved. It takes a good five to ten seconds after the throttle is blipped when warm to return to idle. I've heard this could be a symptom of the idle mixture screw being adjusted too lean, is this correct? After I got it tuned by a professional tuner, the dyno sheet he gave me says he went 2.5 turns out on the air screws. This seems a bit far to me. Possibly the cause of the problem?

I have heard the idle screw being mentioned in plural form, as in there are two of them. However, I have only been able to locate one (which is hard to get at) on the right carb. Can anybody explain where the other is hiding?

Thanks.
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MC21 Honda NSR250. TYGA 300 conversion.