The speedo works on my bench, so that's something.
Have entered the tire circumference after about 5 minutes of figuring out how to do it. Waiting on the solenoid, switch, and male 2.5mm crimp terminals from Amazon, which are supposed to be here Sunday.
Will be using the speedos turn signals, hi beam, and neutral lights. I can tap into all those right at the idiot lights on the nacelle. The running lights will be tapped into the fog lights on the sidecar.
Still need to figure out how to stop the fuel gauge from flashing. Grounding is supposed to work but I haven't had any luck doing it at my power supply. Might work differently once on the bike.
Still need to fab a mounting yoke to secure both the solenoid and speedo in place but need the solenoid in my paws before I can do that.