Aftermarket Tach install?

[Renegade]

Originally posted by TopCatGr58

I'm not totally familiar with Harleys, whether they use 1 or two coils, so I can't comment on the tach exactly, but the HD fires twice, but per 2 Rpms since both cylinders come up to firing position on the same rpm, then rest for an rpm for the exhaust stroke.
T.C.

I am not sure about the newer Harleys, but the older ones used a single coil with the wasted spark like the XS does. When one cylinder is at TDC on a compression stroke the other one is on an exhaust stroke. So an electronic tach for a HD should work on an XS if connected to only one coil.

[TopCatGr58]

Just doing some window shopping!

Look what I found on a few sites:

Tachometer - Electronic
Electronic Tachometer (operates from Ignition pulses)
0-12,000 RPM 1.9 Dia. (48mm.), black face
Tach functions only with single dual output type ignition coils - (80-84 factory Tci,
Boyer micro digital or single dual output coil types).


Part #03-0675 $59.00 USD EA.
**************************************
Electronic Step motor Tachometer
Timex brand instantaneous response Tachometer with Swiss made microcomputer
controlled steeping motor.
0-10,000 RPM white face tach is controlled in steps of 0.08 degrees with a
maximum angle deflection of 240 degrees.

Bevelled glass 2.28" (58mm.) Diameter face has LED illumination.
Case is approximately 30mm. (1.2") thick (thin ! ) and is held in place by a
band clamp bracket (not yet in stock) or fitted into a dash plate mounting.

Note: This Tachometer has micro-switch adjustments to allow it's use on multiple
cylinders and various types of ignitions.




Part #03-0678 $99.00 USD EA.
****************************************
Partsnmore:

ELECTRONIC TACH.



PART#03-0739 $75.00US EA.

The ones I found on the ritzy sites like BikeBandit and Dennis Kirk were in the $200-$400 range!
T.C.

[DavesXS]

I didn't see that this thread was getting responces untill today.
Thanks guys,

Currently I have a 4cyl tach hooked to what I believe is the signal from the stator going to the ignition unit. (green wire). The voltage is low at idle and doesn't register. But soon as you give it gas it moves like a normal tach.

I have a HD tach on the way, should arive today
http://www.debrix.com/items/item.aspx?itemid=1945719

I'll let you know the results.

[DavesXS]

UPDATE

Ok time to update thread for future searchers.

Installed a V Twin tach. Signal wire goes to neg side of 1 coil.

Thats it, nothing else to it.

[Dennyz]

Several years back, I helped get an after market 4cylinder automotive tach to work on an XS (XS motor in a race car).

The XS is two, 2 cylinder motors running 180 degrees out of phase (ignition wise). I built a very simple circuit (under $5) that used a CMOS NOR gate IC, a couple of resistors (pull ups) and a capacitor(decoupler) to integrate the two ignition signals from the coils into a single 4 cylinder signal. Worked like a champ. The components can be found at any electronics store (include Radio Trash).

Five wires can be soldered directly to the 5 pins (making sure none touch) along with the resistors and a capacitor, then the whole thing dipped in Epoxy to make a strong sealed adapter.

1) +12v to pin 14 (VCC)
2) Ground to pin 7 (GND)
3) from one coil to pin 1 (1A)
4) from other coil to pin 2 (1B)
5) output to tach from pin 3 (1Y)

More on 4001 NOR gates

In the above example, the "Inputs" are just like the coils but inverted (ground triggered), so the resistors need to be wired to the +12v as "Pull ups". The "Indicator" represents the tach. The decoupling capacitor minimizes pulsing of the source voltage (+12v).

[justinc1081]

digging up old thread

So had to dig this thread up, i installed an all in one tach/speedo from eBay, cheapo $26 chinese unit, speedo works fine, tach does not register at all when connected to neg side of a coil. Wondering if i should dare connect to the white wire for OEM tach.
THis is the one i bough FYI - http://www.ebay.com/itm/12000-RMP-km...RXzOoR&vxp=mtr

So far everything but tach works great, im using 6th gear indicator as oil pressure

[justinc1081]

I should clarify i have the tach wire for the guage connected to gray wire on bike harness side, think it makes a difference if harness side or coil side?

[3Phase]

Maybe the tach's dead, does it work if you hook it up to a different vehicle?

The White wire for the XS11 tach might trigger the new tach but the divide/count circuit probably wouldn't show the right RMP <sic> on the display.

[justinc1081]

i think i found the issue, i had spade connector that came loose

[3Phase]

That'll do it, yeah. Glad you found it!

[justinc1081]

well that didnt work either, i even took the wire straight to coil, tried both sides. Could be dead tach, i dont expect perfection for $26 lol. I still have my OEM one and will connect it for tuning.

[TopCatGr58]

Hey Justin,

I looked at the wiring diagram on the eBay advert, the RPM sensor wire is the purple/black one. It should be connected to the gray or orange wire side of the coil you choose.

I also installed an all in one gauge cluster set on mine a couple of years ago. The default setting for yours is 1 cylinder. Did you change it to be for 2 cylinder? Ihad to change mine to that mode for it to count the pulses correctly. Each coil feeds 2 cylinders, but unlike a car that fires only once for every 2 rpms, ours fires for every rpm because of the wasted spark design.

Here's page 3 of the thread I made regarding this install if you want to take a look.
http://www.xs11.com/forum/showthread...ic+tach&page=3

T.C.

[justinc1081]

Hey TC, tach is set on 2 cylinder right now, it wasnt moving at all though, only the initial sweep when i turn power on.
I had it tied to the gray wire but for the meantime disconnected. Ill tear into it again soon, trying to research before cutting and soldering more wires.

[justinc1081]

Soldered tach lead from chinese tach directly to tab on coil for gray wire, still nothing..
Decided to re-install OEM tach and just move the chinese unit over a little so i have 2 gauges again. I broke my OEM speedo which was the reason for replacing it in first place, so chinese unit handles speed and turn signals, oil, Neutral indicator.
OEM tach handles high beam, Fuel, and engine speed of course

Think the chinese unit is just not working for the tach part.