jumpy aftermarket tach.

[joelyons50023]

I have a sunpro 5'' tach and ever since i have hooked it up it is jumpy so i put a resistor in i think .5-1 ohm helped it out a bit til after 5k then jumpy again. my question is should i just use a bigger resistor or do the mod of using diodes to make a four cylender signal for my tach. with two coil signal wires?

 

[Thevmaxrider]

My ProCycle tach is jumpy down low, but that is quite normal. A performance tach is not "buffered" down at the lower rpm ranges because most people don't care about the tach at idle. Mine steadies out once I hit about 3k rpm and works great all the way up (ends at 10k rpm). If your tach is reading the correct rpm then doing the diode "mod" won't help. I am not a fan of that particular setup because should a diode short out you will be backfeeding two coils at once which is a bad thing. I would check with the manufacturer first off and then see what they say and go from there.

 

[tugla]

sometimes its a stupid thing like a bad ground wire that causes them to be jumpy, but that's usually down at low rpm, so if its not then then for sure just as Jim mentioned would be a good idea.

 

[satariel666]

I have a sunpro 5'' tach and ever since i have hooked it up it is jumpy so i put a resistor in i think .5-1 ohm helped it out a bit til after 5k then jumpy again. my question is should i just use a bigger resistor or do the mod of using diodes to make a four cylender signal for my tach. with two coil signal wires?

Resistor would do nothing here. Most digital tachos works with any cylinder so theres no big deal here.
I've doubt about diodes too.

Imo you may have a problems with spark, Try to connect to another cyl and see what happens.
You have spark reading fluxuations not current or voltage overloading.

 

[joelyons50023]

tried on all four coils the orignal tach. wire, and the yellow wire by the tach. wire the coils work the best at first it was jumpy all over and once i put the resistor in it setteled down until after 4k, grounds good. prob just the fact it is not a high quality tach. but it is not a crummy one either i guess that is what cold weather is good for is playing around with ideas.

 

[Thevmaxrider]

I would contact the manufacturer. My ProCycle is wired directly to the stock tach input wire and the power/ground wires as well. Know you probably have, but check all the connections again just to make sure one isnt loose. I got pissed because my tach went all wonky on me and then found out that the power wire was coming out of the connector. Fixed it and now works fine. Electrical issues can be a bitch:bang head:

 

[Elimax]

Hi Jim:

Which model ProCycle tach do you use? Thanks!

Elimax