I tried doing something similar, except for my GoPro (Hero 3+ Silver) doesn't seem to recognize the mic and all the sound recorded was still from the GoPro mic rather than the external one I plugged in. I looked around online and it seems like it should be a simple plug and play, no need to change any settings on the camera, but for some reason mine doesn't work. I tested the mic by plugging it into my computer and it works just fine, so unless the adapter is dead, I'm not sure what's wrong.
2007 ZZR600 (sold)
2006 CBR600 (sold)
2010 1198 (parted out across North America)
2013 CBR500R (race bike)
2009 ZX6R (race bike)
2015 R3 (project bike and future race bike)