Hi guys,

I know that I should be asking the seller of the tachometer (bought it on ebay), but I've decided to ask you first as you might have much more experience on that.
I bought this tachometer with the following wiring instructions:
Black -> positive electrode
Green -> Negative electrode
Yellow/Black -> signal
Orange -> positive lamp
Blue -> negative lamp

I connected the green and blue wires to the negative, black and orange to positive and the yellow/black on one of the coil's inputs. I've read that the signal should be connected to the negative input of the coil.
This is my first question. How do I recognize the negative input?
My second question is why the hell isn't working?

The description says that is suitable for 1,2,4 cylinders and 4,2 stroke engines.

I've noticed that if I invert the two inputs on the coil, the engine starts normally...

The internal night lamp lids normally...

Maybe this will help too, didn't see the ryca post before I found this one.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1221683647

I put one of these on:
http://www.trailtech.net/digital-gauges/tto/tach-hour

Cheep, Easy.
Set to:   "2"   and,  "low".