There should be a brass disk oposite the high speed needle valve.  The disk is moved with a little ecentric screw at the 12 o'clock position.  The disk is attached to a tube inside of the spray bar that has a cats eye opening that is the adjustment for low speed and mid range.  The adjustment range is quite small.  I don't remember whick way is lean or rich. Go to MECOA.COM and look at the user guide for the .45 Sportster; it will tell you how to adjust it.  Run this bushed engine with 4oz/gal of castor and 10-15% nitro and you will have a long lived reliable engine. Make sure the o-ring on the disk assembly is snug.