VL 125 Intuder mini tachometer

I have got a mini tachometer for my VL 125
1: Green wire to Negative from coil.
2: Black wire to Ground
3: Blue to lights
4: Red to 12v ignition> were is the best place to connect this so it will turn on when Ignition switched on
if you could put up to pic's up that would be great
https://i.servimg.com/u/f76/17/79/64/45/10017611.jpg

Red to 12v ignition just means to any non hot wire, for example any wire that is only live when the ignition is on

Dale don't know about the 125 but on the 800's there's an ignition live in the headlight

I have tried finding a VL125 pdf manual to look at the wiring diagram but can't find one anywhere