digital tachometer issues

[jonmasaya]

Hey all. Been spying on these forums for a while, but finally need some assistance. I recently purchased an Acewell digital speedometer/tachometer, and have everything working fine... except the tachometer. My bike is a 1982 GS750EZ. The original tachometer was mechanically driven.

I wrapped the tach wire around one of the spark plugs, and I get a solid rpm reading, but the screen fluctuates in brightness and occasionally goes blank (resetting the clock and trip memory in the process). I'm guessing the computer is getting overloaded with current and pooping out? Is there something I can put inline to regulate the flow (capacitor?). I've also tried hooking the wire to the leads on the coils, but get nothing.

Thanks for the help!

[posplayr]

I wrapped the tach wire around one of the spark plugs, !

Huh????

Whta pray tell was the point of that?

[jonmasaya]

It's either that or cut open the plug wire covers. The tachometer reads pulses to the plugs to get the RPM.

[SqDancerLynn1]

I would check the battery connections and your wiring. Check the voltage regulator too !!! High voltage could be shutting it down. Yea, I had a Austin Healey It had a small induction pickup on the back of the tack, 2-3 turns of wire hooked to the ignition made it work

[GregT]

The square dancer may be on the right track - these tachs are sensitive and require a very good earth in my experience.
On twin lead coils I've also struck the peculiarity that it will read one lead but not the other - current direction may also affect them.

Greg T

[posplayr]

It's either that or cut open the plug wire covers. The tachometer reads pulses to the plugs to get the RPM.

Sorry, I see the RPM input uses the secondary as an input.

[dirtyfingers]

Wait...Did you say "wrapped the tach wire around one of the spark plugs"??? It's only supposed to wrap around the spark plug wire. Winding it around a spark plug might make it arc to the tach wire.