2004 GS500 Tach lead

[Alphamazing]

I'm getting my GS dynoed this weekend and the guy said that they needed a tach lead in order to do it. Since it's a Harley store the guy (probably) doesn't have any experience with little Japanese sport bikes.

So, does anyone know what he's talking about and what I can do to find the tach lead? Wiring diagram maybe?

[LimaXray]

just use (-) terminal of one of the coils... this will give you half of your true RPM, but I'd think they could correct for that in the software they are using

[Alphamazing]

Maybe... I dunno. What is the tach lead anyways? Could they just splice it into my tach wires or something?

[John Bates]

From the 04 wiring diagram:

It looks like the tach lead is black/red and runs from the igniter to the tach.  There should be a single bullet connector for this wire somewhere near the tach.

It's probably a lot easier to get the timing from one of the spark wires.