So!
After much deliberation (really like 30 seconds) I decided to use a GPS Speedometer to finish out the summer until I can redo my whole instrument cluster.
I purchased, from Amazon, a DunkTeam Universal GPS Speedometer
https://www.amazon.com/dp/B0BQRDYQ8N?ref=ppx_yo2ov_dt_b_product_details&th=1
The install:
The speedometer instructions say it needs 1 constant power. 1 remote (key/ignition) power. and 1 ground.
I opened the housing, found the speedo plug, cut the plug off, connected my (as per instructions on speedo) power to the purple 12v line. The speedo turned on.
The key was off.
The speedo was on.
I don't like that.
Disconnected the purple, taped that off and isolated it to not cause a short, found the brown wire with a tracer (it's the only brown wire in the cluster) and connected both power lines from the aftermarket speedo (remote and constant) to it. Turn the key and PRESTO! Speedo and backlight turn on, it even sweeps! So cool.
Now I bet you're thinking, 'But Praxiboi, the memory, the trip meter, the odometer, they'll reset without constant power!'
And I like the cut of your jib.
But you're wrong.
Trip meter and odo both held after doing test hits with it and turning it off and on and leaving it off overnight.
Changed the backlight color to red because my wife said it was pretty. You have options, green, red, white, pink, purple, orange, blue.
Anyways, next is the ugly part. The really ugly part.
I forgot to buy a bracket to mount it.
So, like any resourceful idiot trying to finish a project they started before having all the parts and tools, I took my speedo completely off the bike and bracket to see what I could use.
My speedometer, confirmed by a dealer, is fried. Never coming back to life.
So I cut the back end off just above the 2 mounting brass bolts that go to the bracket, cut out a slot for the 3.9m antennae wire, plastic welded (pronounced: Super Glued) that onto the back of the aftermarket speedo.
Electrical taped around the speedo to give it just the little bit of girth it needed to be comfy cozy inside the stock housing, slid that over the speedo and wires, bundled them all up best I could, and tucked her away.
I ran the antennae cord under the tank, under the seat, under the passenger pillion, and mounted it to the rear luggage rack as flat as I could.
Now I did some test hits. I did a full track start from 0 to faster than hell and the speedo
mostly kept up.
Then a relaxed takeoff and the speedo kept up fine. The only real problem I notice is when I stop it takes a second to drop to 0. Not a big deal, tbh, I already know how fast I'm going when I'm stopped.
Testing more this morning in the dark, the backlight is plenty bright enough, the speed versus my phone gps is about 2mph different.
Going to test against a car speedo this afternoon and will report back.
If you have any questions, feel free to get ahold of me. This is a quick and dirty fix to hold me over until winter when I can really tear this thing down and do some better planned changes with real cool instruments. But if you need a speedo now, she goes.