KZ1000 with ZRX Tacho

Hi, looking for help with wiring up a ZRX tacho on my KZ1000
at the moment I have the tacho sign wire connected
to one of the Dyna S neg coil pickup wires, and the tacho seems to be running at half pace
can I connect both pickup sign wires together and try it without damage everything, and will
the coils still work ? The ZRX 1200 uses a ECU for the sign.

Although I have never looked into this or tried it, I remember reading something regarding using diodes on each coil negative wire and connecting them to double up the signal. The diodes allow each wire to send a signal to the tach, but not to the other wire. Might be worth a look into.