750 Maxim Tacho Fitting

Has anyone fitted a tacho from another bike to their 750 Maxim.
I want to know the rev range, and which would do the job please.
A hint to the wiring might help too, I know theres a grey trigger wire from the coils and TCI, also a black (earth?) and a brown (rear light? - is this just for illumination).
I found in a post by Chacal, something about if changing from a 650 to a 750 engine that the tacho has to be converted from mechanical to electric,
so there must be some one out there who knows.
I don't care about looks, ideally just something from another bike thats cheap, the aftermarket ones on ebay are all for cars.
Do any of the other XJ models have the "normal" type and would work?

 

You have an 82 XJ750J with a tach cable??? and you want to convert to an electronic aftermarket or tach off of another bike of some kind.

All of mine have electronic tachs aready. I wonder why yours would have a manual tach?

I would think you would be able to pick up a signal and input it into a new tach. I guess I would be careful not to connect it up wrong and blow the TCI module.

MN

 

Sorry! - I think I was a bit unclear... The PO removed the instruments (atari/fishfinder) and now I have no tacho, I want to fit another - yes, It is already set up as standard (I hope), I just want know which (electric) tacho to use.