rev counter - Stone 1100

how do I wire up a rev counter on a guzzi stone 1100 I have found some info but mostly American, I have purchased the rev counter (vega) it has a black and yellow wire which is the one I need? I think? any one fitted a rev counter to stone?

I wouldn’t sware to it but I think there is a plug already wired up for a rev counter as they used to offer it as a factory accessory

Normally electronic rev counters have 3 connections.

A positive feed from the ignition.
An earth connection.
A trigger lead which connects to the negative side of the ignition coil.gtmdriver2013-12-10 19:39:20

thanks will look in back of speedo housing

would that be the black/yellow wire

On my Cali III the positive wire is red, the earth is black and the trigger wire is yellow/black.