I have a 97 sportster that pops at idle and...

I'd take a closer look at your coil seen many occasions where either the spade connector is not makeing good contact or the sparkplug wire when you you remove it from coil is it leaving any thing behind?sometimes the metal connector stays in the coil if not do a resistance test on plug wires and ck wires from ignition module to coil i dont think youll find anything with a compresion check but im sure id like to see bumbl3b33 look at an injector on a caurborated bike!

hav u done a compression chec on that combust chamber other than that its electrical or fuel related-secure a clymer manual for HD-see them in library alot sec629