first off, the main jet doesnt have sh*t to do with the idle of the bike, zero, zilch, nada !!!!!!!!!!!!!!!
while you were in there changing main jets, you jarred loose a little dirt in the pilot jet < you know, that jet that does have everything to do with the idle of the bike
pull and completely disassemble the carb, and clean it properly, and the air filter too
and i would say around a 290 main with that set-up then plug chop and adjust down if needed
forget about what it sounds like, you're not experienced enuf yet to go by sound, that takes years of practice