when bike is warm, some times when you hit start button it sounds like the starter has a flat spot and makes a loud bang. let off the button and hit it again it starts up. no ryme or reason.any thoughts

 

Does your bike have ACR's and if so, are they enabled?

 

Ever since the 2006 Dyna introduced the new compensator and the other big twins followed in 2007 they sound like a banging inside the primary when the compensator winds up on cranking then snaps free when it starts.

Listen to other bikes to compare if that's what you are hearing.