Motorcycle Repair: installation for a auto meter tachometer, honda cb750 nighthawk, honda oem

Question
Hi,I have a 1993 Honda CB750 nighthawk and I am trying to install a auto meter pro cycle tachometer part # 19325..I Have it set on 2 pulse and have the black wire grounded to the battery and the red pos wire to the battery for now, that leaves the two green wires..I hooked them together and connected them to the ICM box were the original tach wire was hooked up and got nothing (that was only one wire on the ICM box that I hooked to)-( notice the original tach has that wire plus a ground?) ...That brought me to this thought - I was going to hook both green wires (one green wire to the side neg on one of the coils and the other to the other neg side of the other coil)two coil each..But the coils do not have any neg or pos markings except one tab is marked blue on each coil?.now it says that if I have a electronic ignition that I should connect to the tac terminal but that didnt work unless I missed something like maybe the original tac inside has some other contact with another conection that I have over looked to let it work right? Just dont know...Thanks Larry  

Answer
I have no idea why you are replacing the stock tach with this one. I have no knowledge of the installation of this or if it is designed to work with a HONDA OEM ignition system. Power leads should be connected to switched circuits, not directly to the battery.
You should be able to ascertain which coil lead is hot with a 12v test light or VOM. I would suggest that you remove the leads from the components before you start testing.
Electronic igntions are designed with specific parameters and Honda's system may get fried if you attach something with a different resistance value to their ignition system.
I don't have a wiring diagram of later model machines, so am unable to give you a reference as to where it may be appropriate or safe to connect this accy.
I would suggest finding another stock tach instead....

Bill Silver