bouncing Koso RX1N tach needle (Fixed)

The Koso RX1N tach on my 82 GpZ1100 has bounced around since the day I put it on. I have tried every tach signal filter and home grown solution to no avail, it still bounces. I have talked to Pierre at tech services for Koso for a long time trying to get this fixed. He had me send the gauge back to Koso on their dime for testing. Even though my gauge tested OK they sent me a replacement gauge. The problem is still there. I have done the following. At this time Koso does not have a solution for me.
1. Installed Koso tach filter
2. Installed resistors from 10k to 100K.
3. Installed aftermarket tach filter.
4. Made and installed tach filter using resistors and capacitors.
5. Installed new Dyna coils.
6. Took the tach signal from
a. + side of coil.
b. Stock tach lead from original OEM tach.
c. Wrapped tach pickup wire around high tension wire from coil.
d. Tapped into the pulse coil signal wire from crank.
All my attempts have been in vain the needle still bounces wildy. The most stable signal was using the stock tach lead but it still bounces around.

Do any of you electronic savy types have any ideas I can try.

2 things I can think of.
Check your Rectifier for a leaking Diode, causing AC Ripple in your DC system. This can be done real easy, just take your DVOM and place it across the Batt as normal, but switch to ACV on your meter. Should be less than .5 ACV
Then I'm wondering if you have any resistors in your high Tension Leads, Plug wires, Caps, Or plugs? Any one is fine, any two should not be used together, none could be causing RFI and may be the problem.
Oh and make sure you have a good clean ground, as this sounds simple, but can also cause your symptom.

Are you running a Dyna S ignition?
That has an atypical dwell angle, so if the tach requires a minimum "off" time in the signal, it may not work above a certain RPM.

Are you sure it's not mechanical vibration?

My Sunpro electronic tachs work perfectly when they are not hard mounted, but when hard mounted, at some RPMs, the needle starts to bounce a little. It's not bad, so I live with it.

Interestingly, even with the wires all disconnected, the needle on the tach moves as if it's connected, purely due to vibration.

Finally solved the tach needle bouncing problem. I replaced the original IC ignitor and pickup coils with a Dyna S ignition. That solved the bouncing needle problem. I guess the older electronics were not compatable with the new tach electronics or the old stuff was getting ready to go bad. I had several good IC ignitor boxes and pickup coils. I swapped out several prior to buying the Dyna S thinking maybe it would fix the problem but no joy. The bike ran great with the stock stuff and all the stock stuff checked out fine. Weird.

Good to hear it is working correctly now. Maybe Lou has a theory on why it was erratic with Maw Kaw's set up?

The factory ignitor boxes have a tendency to pickup false triggers under certain circumstances. It usually doesn't affect how the bike runs, but will give occasional extra sparks. You can see this if you use a timing light on the pickups. The rotor will mainly fire on the correct rotor position, but you will get an occasional firing on the opposite pickup. This leads to a ghost image of the rotor pointing in the opposite direction. Because the ghost firing is very near the real firing, some tachs may ignore the extra sparks and some may not.

One of the things I noticed when using the HEI igniter was that it seemed to eliminate most of the false triggers.

But shouldn't a tach filter take care of the problem?

Depends on how sophisticated the tach filter is. I doubt any passive filter would do it.

The tach filter, filters noise on the signal from the coil to the tach. The false triggers are generated before the signal gets out of the igniter, which then become real signals.

I know, I know, this thread is ollllldddd. BUT, I had the same issue but resolved it with a different, FREE FIX. Without having to buy any new parts. I have a Koso TNT-01R tach (kinda wish I bought an autometer now lol) that I just bought to fix my bouncy original tachometer. And, the koso bounced when I hooked it up -_-.  yeah I was disappointed. Tried a few resistors and the like to no avail.

Anyhow, I was searching online and found a solution on another forum that I'm not a part of (classicmotorworks - a royal enfield forum). I bypassed the ignition system altogether for the tach signal and connected the tachometer signal wire directly to one of the three yellow alternator output wires, BEFORE the regulator/rectifier. So, the tach sees the AC sine wave, which is clean and is directly proportional to the engine speed. I had to set the tach to "1 RPM Signal per 6 sparks" to get it to display the correct RPM. I assume this is because the tach sees three positive and three negative peaks per engine revolution.

Welp, this made my day and turned me from irritated at my new tach and possibly having to spend more money and buy more things that may or may not fix the issue, to happy that I can continue my project without this being another hang-up. Hope it helped someone!

I try the same on my KOSO RX2N+ GP Style connected to one of the alternator wires. No cure, the same bouncing effect
as on all other low pas filter, resistors, diodes, condenser circuit boards i made.

Here is my solution to eleminate the bouncing effect:

kzrider.com/forum/4-electrical/607690-de...eter?start=20#784802








I soldered a wire to one of the Dyna pick-ups on the backside.
Output is 0,50 - 0,80 Volts square wave with an oscilloscope detected.
The converter, (min. 0,10 Volt input square/sinus/triangular signal = ABS sensor), transforms the signal to a 12 Volt square signal,perfect for my KOSO RX2N+