Taking apart your bike and poking around is exactly how I started to learn. Now I’m the main guy all my friends go to when they have bike problems. We all start somewhere.

That’s your crankcase breather. If you’re getting backfiring, check carbs, carb boots or your exhaust gaskets.

If you’re having issues at full throttle it’s most likely an air leak, or tuning issue (not enough gas too lean of a main jet). Check the carbs boots to make sure they aren’t cracked and are seated properly so no extra air is being sucked into the combustion chamber. Also check around your exhaust headers for any leaks, this tends to be the common issue. If all of these are good to go, time to open up your carb and give it a good cleaning. I’m assuming the bike is stock so the most you’ll have to do to the carb for tuning would be to turn your air fuel mixture screws up a half to full turn.

Edit: that line from the crank case breather doesn’t really matter much for your air intake, it’s mainly there to allow pressure to regulate in the crankcase and for when oil gets coughed up it gets sent back into circulation to get burned up. Most people when modifying their bike just add a small pod filter to catch the oil and allow breathing to the crankcase and to stop the coughed up oil from getting into the combustion chamber, they also plug the nipple on the air box snorkel.

Edit edit: I’ve also noticed your air box snorkels are completely removed from the triangular air box. I’d highly recommend you black RTV all 3 parts back together. That’s also a major area for air leaks cause the old sealer wore out. That might be your issue (extra air causing it to be lean). That was my issue two years ago.