Need advice from the wrenching gurus.. S&S 117 Build

In addition to my Road Glide I have a 1996 Fatboy. I swapped the original engine for a 2008 S&S 117 EVO. I did head work (Branch O'Keefe) and cams. My bike has difficulty starting at times and often leaves me stranded. I always give the throttle a few pumps and open my enricher before turning it over. The bike chugs before starting. It has a single fire ignition and I often get a backfire that sounds like a gunshot. I'm always able to get if going if I jump start it but that's not a solution to my problem. I'm thinking that I may need a higher torque starter. I don't want to invest in a new starter if that's not the issue. Any advise or thoughts are appreciated.