What year and model have you got BigDaddy? There should be a switch for front/rear on the compressor control. If there are no gradations on the bar graph, 4 psa is 2/3 of six, so run the compressor switched to the front until the graph reads about 2/3 on the low section. I think there is a schrader valve on the fork as well so you can maybe put a guage on it to tell more accurately. Just remember the forks hold very little volume so every touch on the valve is going to release a bit of air.