Sounds almost like ur way rich. Popping and flames would indicate excess unburned fuel igniting in the exhaust. Which would be confirmed with the noticably rich plugs. What size jets did you install?
07 vstar 650 midnight custom
Ais disable, 4.5 inch risers, V&H cruzers, jetted with pods, viking saddlebags, Kuryakyn mini boards and memphis fats windshield, fuel solenoids deleted, star solo seat and 4 inch extensions. Boss audio sound system.