You probably don't need to adjust it as much as you need to clean it. There is a screen in the intake side of the regulator that gets clogged which raises the control pressure in the system which in turn makes the engine run leaner than it should during warmup.
I would remove the regulator and take it apart(carefully, make notes if you need them) After you remove the 6 screws from the cover and the clip at the bottom of the electrical connection flip it over without separating the halves, remove the top and note the position of the little pin and mexican sombrero looking piece(the pin is under the sombrero just keep in mind that it is there) remove the 10mm nut and the flat spring(bi-metal) , remove the sombrero and the pin which is underneath it then unscrew the little silver disc down in the bottom, clean out all the passages you see with a spray can of carb cleaner and make sure you get the cleaner to wash back through the fuel line fittings which will clean the screen. reassemble it and bolt it back on. I may have missed an additional spring in there but it will be self explanitory.
There is really little chance of messing it up so tinker with confidence!