The metering blocks(deals with the jets in them) may be plugged up. The fuel can evaporate to leave residual or the cast type can get corosion as well to have the pieces fall off and jam stuff up. Pull them off and check for obvious signs, scrape off the flakes of stuff and such and spray carb cleaner through the passages. Put it back together and it will probably work.
If you were dialed in to begin with and you're going into winter with cooler temps you may need a jet size up to snap up things a bit too.
generic looking metering block for part reference
