Ironhead Sportster tachometer wiring question

[Doc308]

Follow-up: I got a pair of the Jap gauges and they work well on my FXE. The wiring is essentially the same for the tach but I need to get a different speedo cable as the nut is a different size--ie 12mm vs 16mm.

Thanks for all of the help!

[Gasman76]

Hey guys, I realize this thread is fairly old but considering my question is on topic here I figured I'd try it here first rather than start a new thread...

I've got a 1976 xlh1000 and, similar to silky above, I'm trying to run an FX tach on my sportster. Tach is from a 76 FX.

I've got one wire to points side of the coil, one wire to ignition switch and grounded to the ground on the back side of the ignition.

It won't fire with this configuration. What gives?

Any help would be appreciated

Thanks.

[sleighcrane]

What are the markings on back of tach
Not sure if the ones marked ALT will work on sportsters if that is what you have. Any pics

[Gasman76]

https://imgur.com/a/KdyGxw7

link to pic of tachometer i'm using. one wire from IGN to green connection on ignition switch, one wire from COIL to points side of coil, and one wire from GRD to the ground wire behind ignition switch

[joe s]

"trig" hookup and "1 spark/rev" implies to me an electronic ignition trigger wire, not a points/coil hookup

[sleighcrane]

Ok power to ignition. Trigger to coil same side as where points wire goes. Ground to ground