[OLDKID]

Possible plugged filler cap vent (spiders , wasps) , fuel line restriction ( tank petcock , filter , degraded hose ) pull line off at carb and check flow . More than likely Carb. is gummed up from old gas ( gas is only good 30-60 days ) disassemble and clean out carb paying extra attention to holes in the emulsion tube if so equipped ( Carb. schematic , or Mechanic if this is new to you ) . You said it bogs under acceleration , choke is off after first minutes of operation and would not cause lack of acceleration , but hard starting . The part in your picture looks to me like a oil , water , crud drain for the airbox inline with the breather hose to airbox . Just wash it or run the breather hose to box without it . As I've stated before most Chinese OEM box's and filters I've seen are JUNK ! Do yourself a favor and look for 6" plenum/intake and K&N filter for your application , or fab one up yourself . Here is one out of left field .... Exhaust plugged up from mouse nest ?????? SEEN IT BEFORE ! GOOD LUCK .