My 2008 Road King started doing that on cold starts once I added my Rush pipes and DynoJet Powercommander V. The challenge i found with the programmer is it requires the O2 sensors to be unplugged/bypassed as such the bike has no way to adjust for climate changes and no way to read the air/fuel thats running out the motor as such when the air temps got warmer the bike ran a bit lean and would not start right away and turned over 7-8 times even when the motore was warmed up. In the cold temps it would backfire on start up and still turned over a bunch of times before starting. The tuner played with the settings several times but it was always inconsistent when the weather changed. I have since taken it off the bike along with the K&N intake and gone back to the stock ECU program / kept the pipes on and it runs much better and I dont even notice a drop in power which tells me it never ran right. I was hoping to get a local dealer just to flash the ECU with a stage 1 but they dont do that anymore, at least not here in NC as such i was steared to the piggy back programmer.

Good luck...

 

After I added a tuner and Andrews 21N cams to my 05 Ultra mine it would "pop" sometimes on startup. I found that it would only do it when I had my hand on the throttle when starting. I think I was opening the throttle slightly when starting and that is when it would "pop". I now keep my grubby paw off the throttle until the bike starts. It hasn't done it since.

 

Mine does it once in a while and it's stock. Always has for years. Think it just happens when it stops in a position that the first firing cylinder misses and dumps it charge in the exhaust. I do not buy that too rich. In fact, for it to pop, it need just the correct charge to explode and not burn in a cold exhaust. Mine will also do it started about an hour and parking it hot. Think that is rich, and it does not do it as loud. Just my opinion however. It has the factory exhaust off a 96CI last model year Night Train. Did not do it with the Python Long Shots.

 

that Andrews 21N is very close kin to a SE255 on the intake and exhaust timing. Both open the intake late and close it late. The exhaust opens very early and closes early compared to other cams. That's my story and I'm sticking to it. Not really just speculating.

 

check for exhaust and intake leak.

 

Mine has done it a couple of times. Every time it's happened, it's failed to start on the first crank. I let off the starter and hit it again only to have it start with a backfire. Not too concerned though, had the bike for almost 3 years and it's only happened 2-3 times.