Ask for rec to a competent tuner (not at HD dealer). Most of the PHD's I've met I wouldn't let them tune my wheelbarrow. Detentation or pinging is resolved by tuning correctly, obviously your not there. It is caused by the fresh charge igniting on it own instead of being fired by the sparkplug, usually due to extreme lean conditions or carbon buildup causing hot spots in the combustion chamber. I'd bet on way lean in your case.
Next time your out riding and you get the noise, knocking, shift down one gear, never let the motor rattle away until you get up to speed, major damage can (will) occur.
All these new bikes are geared way too tall, and people think they can drive them like the older, lower geared bikes. You shouldn't be in 6th until 75 mph IMO. twinotter
