yes it is listed as #3 in the parts diagram ( I dunno what year you are dealing with). I just bought the carb kit off of ebay. Came with pretty much everything except a float and the diaphragm thingy for only a few bucks more than the factory needle jet set.
I does make sense that turning the mixture screw out a few turns would somewhat compensate for a undersized pilot jet.
This is how mine is setup. For riding at altitude in Montana. Which I know has no bearing for you at basically sea level. Plus your bike is probably a heck of a lot newer (all most everybody's bike is).
87' xr250r no snorkel, uni filter, super-trap exhaust (8 plates) with the welds ground off inside of header
42 idle jet
clip in middle position (3rd groove from bottom)
air mixture screw 2.75 turns out
Sometimes the bike shop will just trade you out jets.