Seems to be heat related. If I run to town at 60 (13 miles) it will idle high till the bike has sat for awhile. If the motor is just warm it idles at 13-1500 like it's supposed to. The idle was set after riding around the yard for a bit, not after a highway stint. Could that be some of it?
A good carb clean and inspection is the first step.
I'd check for carb sync, a lean pilot circuit, and/or vacuum leak of some kind. Check the carb phenolic insulators for cracks and make sure it's a good seal. I've heard some use silicone to make sure it's sealed. Just a few suggestions.
"You can lead a person to logic but you can't make them think"
The phenolic spacers (between the carb spigot gaskets) have been known to crack. I'm wondering if the heat of the cylinder is opening a crack? Be sure there is some slack in all cables to the slides. Another possibility is the crank seal under the alternator rotor. If you find oil residue in the alternator case this too is a possibility. Either a slide(s) is being held open somehow or there is an air leak(s) causing the issue.
+1 on gluing the carbs on to their spigots too. (Watch that you don't plug the tiny pilot outlet passages at the intersection of the carb to spigot though)
check the carb tops on all 3 cylinders too. a loose one will bring up the idle.
use ultra copper exhaust silicone on the spiggots. coat the whole spiggot thin except for an 1/8 inch away from manifold opening. Do the slits in the carb mount. Don't get it all over and dripping to alter the air flow. Completely wipe off any on the phalic ;D seal, leaving only the slits filled. Slide on the carb and you should end up with a nice ring of copper sealing things up bettter.