[110duke]

Hey guys I have a 110cc engine and I’m using a eBay universal speedometer and when I hook the tach to the black and yellow wire ( the one on coil) the screen dims and doesn’t turn back on unless I turn off the power and turn it back on.

The second the screen dims is when I touched it to the yellow and black wire

 

[kirrbby]

Does your tach have instructions?
Does it tell you to use the black/yellow.
The cheap universal tach's I've seen have 2 wires...one goes to a frame ground. The other WRAPS AROUND the spark plug wire. It doesn't connect...just spirals around the outside.

 

[110duke]

Does your tach have instructions?
Does it tell you to use the black/yellow.
The cheap universal tach's I've seen have 2 wires...one goes to a frame ground. The other WRAPS AROUND the spark plug wire. It doesn't connect...just spirals around the outside.

No it doesn’t, it has instructions in that it shows which wires do what