I don't understand how it can run hot with no spark. Please give more detail.
Plug gap for the Sportster 883 or 1200 should be .040
.028 to .035 according to spark plug brand.
.04
.40mm is the recommended gap
.040
.038-.042
.040".
HD 6R12
most likely a bad coil
The gap setting is 0.034 to 0.037.
Manual says .038 - .043
40 to 45. 40 is common.