Hawk Digital Speedometer Upgrade Problem

[Hawks & Turkeys]

About 4 months ago I purchased and installed the RPS Hawk X 250 (carb version) digital speedometer cluster. And...it turned into a cluster

For those of you who have survived the upgrade installation, you know that there are about a half dozen wires, all of different colors, that are "pinned" into a wiring harness. Then there is one wire, blue & white, which is not pinned, but clipped to, or taped to, an unspecified wire in the harness, and that is for the new tachometer.

Well, smart guy that I am, I attached the blue & white tach wire to an existing blue & white wire in the harness...same color, has to match up, right? WRONG! Turns out the existing blue & white wire runs from the CDI box, and by attaching the tach wire to it, I wiped out the digital signal and the engine wouldn't start for a month. I had to pull the whole digital cluster out, and reattach the old analog speedo cluster to get the bike running again.

So does anyone know specifically what color wire the blue & white tach wire should be attached to?

Thanks!