You have intermittent spark on one cylinder.
Possible causes:
1) Most common... Bad/fouled plug (Buellizm #54 Repeated cold starts without warming it up WILL do that)
2) Bad or poorly connected plug wire
3) Bad coil
4) Primary wiring to the coil is compromised
Possible repairs:
1) Clean or replace the plugs NGK Iridium work well either DCPR8EIX or the 'colder' DCPR9EIX.
2) Check or replace the plug wires for $22:https://st-paul-harley-davidson-buel...710051e0&_ss=r
3) Replace the coil for $42: https://st-paul-harley-davidson-buel...6cc8acb5&_ss=r
4) Check 12V spark signal at the coil terminals #1 and #3