start simple and cheap,
fully drain and empty the tank, remove it, turn it upside down, shake it out, blow it out with air....make sure it is clean and dry.....and then
also drain the float bowls before refilling the tank........one single drop of water can and will completley plug a low speed circuit in a carb, and stay there untill it is dislodged. re-fuel using a new clean gas can,
add 2 gallons of clean fresh fuel mixed with a bottle of IsoHeet. run the bike hard.this bogging and bucking is very commonly a water thing, and it comes on like right now with little or no warning, not like a degredation of engine performance normally associated with things "going bad". If you didn't do anything mechanical to the bike prior to this occurance to create the instance, my money is on water.
as for seafoam, it works when used regularly, but I have never had success with it removing water as well as IsoHeet, or Heet. adding this stuff doesn't do a thing untill it is run thru the system, and seafoam does NOT bind up water. IsoHeet does,
you still have to ride the bike to burn the fuel/water/IsoHeet mixture up....letting it
sit in there does absolutly nothing.
the way gas is today, if my bike sat for more then a month, I would completly drain the tank, and start from scratch.... don't even hit the starter...just don't.
worst thing you can do is figure "lets start the bike and see", because that is where you totally gack the carbs up, and nothing is gonna reverse the problem that you created by starting the bike with poopgas.