Voltage issue - Gauge Cluster and wiring Questions

[FirstOwner69]

The black and white fused wire is positive. The end near the right headlight goes to the junction block on the right fender adjacent to the battery. There should be a loop on the end to go on the stud. The other end is the black and white wire included with the red wires in the soldered wire connection in the pictures. I believe I read in another thread that this wire is basically a shunt that measures current drop/rise causing the gauge needle to move. I'm not sure why it would spark unless the wire has a bare spot that is grounding. If you want original appearance, I'd stay with the ammeter. Most people do feel the volt meter gives more relevant information.

The correct temperature sending unit for the factory gauge is probably not the one for the aftermarket gauge. If you can post a picture of the one you have, we can get a good idea of what you are dealing with. I have no idea why there would be a wire coiled around it.

The speedo jumping around may be fixed by lubing the cable. I'd try that before getting a new gear. In addition to a cable kink or need for lubrication it could also be caused by use of a lubricant that has dried out causing the cable to momentarily bind as it rotates. You said, "I know its not original, because there are two. The original is still there just not hooked up." I'm not sure I understand what you are describing.