Can you tell me what it was Jremmee? Funny I'm in the EXACT same boat here. Just bought the bike, a 2007 SM and have the same issue except my carb is not dirty like yours.
Also my the white knob (idle adjuster?) is turned all the way in as far as it will go. Looks like PO was trying to get it to idle higher so it doesn't stall without choke. He told me it needs to warm up for a very long time before you can push the choke back in, which doesn't sound right, especially here in Florida.
Also bike only has 1600 or so miles on it, and PO used a Dynojet kit, not the JD like yours, and I know that the 155 is in there.
Looking for suggestions on what to try first... issues are:
1) Won't idle without choke
2) Pops loudly on deceleration
3) Idle adjustment knob at max
Going to go look for a service manual now.