2002 harley electra glide front spark plug turns black

A blackened spark plug is a sign of a rich air/fuel ratio or a misfiring plug. You stated that you changed the coil and wires, but did you change the plugs? Spark plugs, even new ones, can, and do, go bad (excessive internal resistance). Make sure that the plugs are also the correct part number for your application, as they could be of the wrong heat range for your bike. I have even heard of guys using a colder plug in the rear cylinder and a hotter plug in the front cylinder because the front cylinder tends to run a little cooler than the rear (increased air flow in the front).