750 Maxim aftermarket Tacho

-'82 750 Maxim J-
As the PO has removed the whole "atari console" I am wanting an aftermarket tachometer... question is, where do I connect it to?
I assume the original wiring is in the loom still, does anyone know what colour the wires are and maybe which part/branch of the loom to look in?
Is coming from the igniter or pick-up coils maybe?
I would also consider a tacho from any other model or even make - if anyone knows a suitable replacement - as the bike has progressed far from standard - even approaching rat status.

 

It would have run to a connector in the headlight shell or somewhere in that area, to allow the "fishfinder" to be easily unplugged and removed.

 

There's a 3 prong connector, prolly in the headlight.
Brown's for the back light.
Black goes to some random earth
grey goes to coil (cyl 2/3)
Mikexs sells aftermarket tachs, be sure not to get a cable driven one.

 

btw get a tach that's suppose to run with a wasted spark.

 

Not sure I know what u mean, does it connect to the CDI (TCI)?
Whats it called or known as?

 

The stock tachometer gets it's input on the grey wire which goes from the coil pack to the TCI.
The XJ's use an ignition system that utilizes a "wasted" spark system. That is to say that for every revolution, either 1-4 fire or 2-3 fire. The cylinder that is at TDC on the intake stroke will fire and the alternating cylinder (which will be on the exhaust stroke) will fire as well, a "wasted" spark. This perportedly helps with emissions.
Does that answer the question?

 

Thanks Robert, clear and concise, thats what I wanted - the aftermarket one on ebay apparently is for a car so prob runs from the coil.