coil question

[kenco]

Hi, I've wired in a digital speedo (from danmoto), The last wire is a little bit puzzling because the wiring diagrams arent that great. To get the rev counter to work I need to get a feed off the coil but I'm not sure which wire to do it from. As company called Acwell do a similar speedo and the say do it off the positive wire. But i'm not sure which is the best colour or positive wire. I thought the red an white wire was the best option. The bike is a 77 D with standard coils. Has anybody got any ideas or done anything similar.

 

[xjwmx]

I would clip it to one then the other and see which it liked best.

 

[5twins]

I think it goes on the points wire (orange or gray), not the R/W main power one. The R/W is going to give you a steady power feed with no variation. The points wire signal will pulse with the opening and closing of the points, giving you an RPM reading.