I have 1994 fxdl the plugs keep getting caked with black soot and fauling out which makes me believe its running to rich, its also backfiring,thru carb and exhaust, i want to know how to lean it out

Before I can tell you how to lean your carburetor out, I need to know what kind of carb you have. But, there are other possible causes for your problem. The factory usually jets the original Keihin CV carb too lean to meet EPA emission requirements. The most probable cause is running the enricher too long while warming the engine up. The enricher on any carburetor provides an extremely rich mixture. So rich that it will foul plugs if allowed to run for too long. You should only use the enricher long enough to warm the engine to the point to where you can keep the engine running with the throttle grip. Once the engine will run with the throttle grip, simply idle the engine up and use the throttle grip lock to hold the throttle at this setting and push the enricher knob in. Other causes could be that the needle is not seating properly and allowing the carb to load up with fuel. If this is the case, you should have noticed that the engine is idling extremely rich and poorly. In this case, you'll have to at least drop the float bowl off and replace the needle and check the float setting with the new needle. The Kiehin CV must be positioned on an angle to set the float properly. If you still have reason to think that you need to change your carb's jetting, re-post telling me exactly what carb is on your engine.

Good Luck
Steve