If you wish to connect the ignition coil, the SPA tacho is fully protected. It will connect to any coil including magneto's and is not damaged by reverse polarity. Connect black to chassis, and red to the ignition pulse side of the coil. Do not make any kind of connection to the HT leads or the spark plugs, this voltage is highly destructive
So my guess is to splice both the skinny black, and green tach lead with the "eye" terminal directly to the frame ground in the picture below. And my gut says the red should splice into the CDI line right there.
The coil installation schematic is in the lower right of this page from the manual. When I first read this, it sounded like I should patch the red tach lead into the green/ground lead of the coil because it has a (-) insignia at the terminal on the coil...but that just doesn't make any sense to me!
The bike's wiring diagram is fairly simple as far as these things go.
Below is a table of the various connections to the meter's body. The 10 element array is the one I'm concerned with.
Aside from the +/- leads coming from the tach sensor at the coil which we went over at the beginning, there are 3 other leads attaching here that I need to safely incorporate into the bike's harness somehow:
- Ground was easy: I just spliced it into the same ground line used for my front turn signals.
- Red "+12 Volts Battery" lead. It has an inline fuse. I had originally spliced it into the red battery line by the ignition switch, but that made no sense because the tach's LCD lit up as soon as I connected it. Perhaps I'm supposed to use something called a "relay" to mitigate this, but I see no mention of doing so with the tach installation instructions.
- There is another red lead with a label on it: "lights on" presumably having something to do with...lights.
Curiously, I tried connecting the "+12 Volts Battery" line to the brown line in my bike's wiring harness, thinking it the tach could use the same line that my tail light uses (which switches on with my ignition key). THAT seems to work okay in that the tach powers on only when the ignition is turned on, no idea if I'm overloading my circuit insodoing...presumably the tach doesn't draw that much power tho ???
Oh well, thanks for reading through this for me. If you have any ideas I'd love to hear them. I look at the map on the upper right corner of this window tracking the visitors and wonder what you all are up to?