I am riding a 2004 VTX 1300C. I changed spark plugs today, four out of five were medium carbon coated, the other was very clean. Not wet, but black, gap was not out of spect,31 to 33.I have also had a few decel pops, not every time but enough to get my attention. Looking up reasons why, i find rich/lean solutions. They mention the "A/F" screw to change the rich or lean mixture. My question is, where is the A/F screw ? Is this in the carburetor, and do I have to take the air box off to get to it ? Thanks for the input.