XJ900F Tachometer/Electrical

Thanks rooster. I actually do have a nice scope, but I didn’t think to use it (amateur here ). Maybe I will re-test that signal.

 

I tried another tach on the bike and it also isn’t working. I think I need to investigate the signal wire further. I tried tracing the signal wire but I lose it after it passes under the headlight.

I imagine the tach gets signal from the coil, but I don’t see where. Does anyone know?

I need to learn how to read an electrical diagram

The bike is a yx600 which has a xj600 engine.

 

I looked into this more and I may be able to figure this out myself.

Here’s the wiring diagram. It looks like it gets the signal from the 1/4 coil.
http://www.badrad600.com/Wiring Diagram (1986 Owner's Manual).pdf

 

I’m revisiting this tach issue today. I’d like to just run a signal wire directly to the coil to do some testing.

I’ve read that all I need to do is wrap a wire around one of the spark plugs, then tie it back into the signal wire on the tach.

Can anyone confirm?

 

I would just stick with OEM design and figure out what is wrong. Since you tried another tach (know good I hope) then either the power or signal is missing. It should be very easy to verify continuity of the orange wire (signal) that goes to the tach by measuring from that orange wire at the tach to the orange wire on the coil - or the orange wire on the TCI if that is easier.

 

I found the issue today. The signal wire was corroded completely through in the headlight bucket.

Thanks for keeping me on track!