So instead of fixing the killswitch, I decided to focus on getting the bike to idle properly. I tried a bunch of stuff: velocity stacks on, off, stock airbox on, idle screws all the way in and adjusting out in 1/8th turn increments and eventually I got the bike to idle well with the choke off. The catch was that as soon as you cracked the throttle the engine would cut out. Whether it was a quick blip or a super slow 'squeezing' of the throttle, it quit. So I reluctantly pulled the carbs off the bike and did some exploratory surgery. I didn't find anything other than some floats that were off by ~1mm on one side only. I seized the opportunity to unfreeze my drain screws just in case I had to clear tube test down the line.
I put everything back together, slapped the carbs onto the bike with some help from my $8 HF heat gun, socked down the clamps, hooked up my new auxiliary tank (those things are helpful, I wish I had bought one a while ago), and started it up. I don't know what I did, but it now runs without the choke. I have only three issues:
1. Bike idles high. I think this is due to my hurried bench sync (shame on me). With the idle screw backed completely off the engine is idling around 1600 rpm. I'll inspect the throttle slide positions and try to adjust them down to reduce the idle speed.
2. When I give it throttle, it quits at around 5k rpm. I have to give it quick blip as the rpms are falling to keep it from shutting down. I'm not sure if this is related to the first issue, but I'm hoping it does.
3. There is smoke. It is either an exhaust leak at the head, or it is powdercoat burning off the lower frame rails. The 4-2 I have on it is super close/rubbing on the frame.
Here is a link to a video of the high idle/smoke:
Before anybody freaks out I have the oil and neutral lights switched in the bezel. The neutral lamp is on, the oil lamp is off.