Pilot or air/fuel screw setting?

What is the recommended number of turns for the pilot screw ( the air/fuel screw) on a 1982 Honda Nighthawk 450? I recently set it to 2 1/2 turns out but it doesn't seem to be getting enough

Two and a half turns should be about right but what aren't you getting enough of? Fuel or air?

Not rocket science. Just follow the tuneup procedure in the shop manual. Recommended means recommended, dude.

The pilot screw only adjusts the idle and slow speed circuits (1/4 throttle opening)
If you are not getting "enough" of something, the jetting will probably need changing.

My first question is why you are having to adjust it? I'm not trying to be flippant about it--it's just that this is an adjustment that is rarely required. In most cases, idling or drivability problems with motorcycle carbs are caused by other factors, and once you get into the fuel/air mixture, you're setting yourself up to introduce yet another variable that you'll have to verify is correct. In fact, most carbs have a service plug covering the adjustment screw hole and in many cases, I've seen motorcycles that are 20+ years old that have never had this plug removed. Valid reasons to adjust the screw are usually a change in other carb parameters (for example, you've changed the jetting or other internal components), or the carb has been completely disassembled for service and you're putting the screw back into its original position.

As the previous poster stated, 2.5 turns should be good--it's a least a good starting point--and if you're having significant problems even after this adjustment, this is further confirmation that something else is going on. The service manual will of course give you the preferred way to perform a precise adjustment but in general, if you turn the screw in either direction while the engine is running you should be able to hear exactly what you need to do (it'll have a definite peak in which it runs best).

The most common reason that I've seen for a poor (or non-existent) idle (assuming that the engine revs properly at higher throttle positions) is a clogged idle jet. This jet has incredibly small passages--probably thinner than a human hair--and with all of the additives in today's gasoline, it doesn't take much for one to become clogged. A confirmation of whether it's in the idle circuit is to try to give the bike just a little throttle during idle. If it runs fine with the throttle but not without it, this confirms that the fuel is getting to the engine from the main jet when you've twisted the throttle, but when you've cut it off, there's not enough fuel from the idle jet to keep it idling.