valve adjustment needs

So I have recently been experiencing problems with my motorcycle. General description: the bike bogs and backfires (out of the carburetor) when too much throttle is given within a short amount of time... My father and I have ruled out the carburetor, A/F mixture screw, plugs, plug wires...

I'm getting conflicting input on valve adjustment on a new 1300. One group says you MUST check the lash because you're risking burning a valve if the lash is too low (valve not closing all the way.) Others say don't worry because carbon buildup, seat expansion and cam/lifter wear all go...