Just put a stereo , amp and speakers in my 2012 road glide and it sounds awesome then when I start the bike I hear a high frequency noise out of the left rear speaker

 

I'm no expert, but i'd check ALL of my wiring, paying close attention to my grounding wire/source. Once you've established you're ground is good, check the speaker connections on the side in question. Process of elimination...next check for anything that might be interfering...powered antenna, Gps, CB, etc.

 

Good advice. Here is little more detail: http://www.crutchfield.com/S-TVHJYMZ...ion_guide.html

 

Thanks, bad ground. Ran 1 from the battery