I ended up getting it pretty much dialed in:
- I set the throttle linkage stop between the throttle bodies. Spec in the manual via the DI diagnostics (this is the first reading) had it at 15-19, I believe for closed. I ended up having it set right at the high end of 18. Anything less and it would idle down to less than 800 and die. Anything more and it would throttle up. It's a VERY sensitive adjustment but have the DI screen up helped.
- New plugs. I don't think it needed them but it's cheap insurance. There were some dual prong iridium type in there, now it is just the stock NGK coppers.
- New battery. Went with a 20 series AGM from O'reilly and it fit perfectly without the foam spacer.
- I spent several hours fiddling with the C0 adjustments, and ended up at -50!
- The black idle adjustment knob still doesn't do anything.
The idle RPM's are up where they should be. Anything leaner and it idled too high, especially when cold. Anything richer (less negative) and it really struggled to stay running at idle when warm. Anything richer than -15 resulted in popping out the intake on quick throttle blips. We've had it out for a few rides since and it runs great, hasn't died coming up to a single stop, and hasn't quit idling on us yet.
Keep in mind that when I balanced the throttle bodies, all 3 screws had to go in significantly, which I'm assuming restricts airflow. Since I pulled a bunch of air out of the idle circuit, it would make sense that I had to lean the mix out to compensate...unless I am not understanding part of the system properly.