Aftermarket Tach install?

[DavesXS]

I only have a speedometer. Looks cool with the single gauge, but I need to see engine rpm to tune.

Can some one give me the short version of what to hook it too? (signal wire) It would save some time.

Thanks
David

[Crazcnuk]

For tuning, get an aftermarket digital diagnostic tach. One that moves in increments of 50rpm.


The stock tach is not accurate enough to do decent tuning with.

[DavesXS]

thanks for the info. But for now, I want a full time tach(good after market not stock). Once I am comfortable with the bike I'll remove it. But right now I don't know what its idling at, and I belive I am pretty sure I have red lined while stretching out gears, and listening for carbs to be flowing right at high rpm's When I remove the tach I'll have a small shift light set at 7k. When I got it it was idling low. I think the guy wanted a vtwin like idle. But for all I know I might be idling 1500 now. I am hoping to figure out if the guy jetted it correctly too when he added air filters and 4-1 header.
Where do I find a book on these bikes? Thats usually the first thing I do when purchasing an automobile.

Back to the topic...After market tach, any ideas on where the signal wire will connect?
If it makes it easier, you can just fill in the blanks.

The tach will hook up to the _________ in order to receive signal. Located ________.

Thanks

[DavesXS]

you know, if this thing had a distributer I'd have it hooked right up.

After 28 years of owners and a forum dedicated to xs11, you'd think some one could tell me where the signal wire is. Or at least tell me where to get the book for this bike.

[DavesXS]

Just in case theres any doubt. I do know what search is and this is all I can find. The only thing about a tach on the wiring diagram is 2 tach lights. But no way to tell whats the signal wire. So unless some one knows first hand where this wire is, I guess I can just strategically poke the wire into places until it either works or burns something up. Only way to learn is be taught, or trial and error.

http://members.fortunecity.com/imlucky/fullwire.htm

http://webpages.charter.net/kbhahn/xs11/E-Fwire.JPG

[TopCatGr58]

Hey Dave,

Sorry, can't be everywhere all the time!

Our tach doesn't use the same kind of trigger wire that most auto tachs use...the one from the negative side of an ignition coil!

Ours runs off of one of the 3 legs of the ALT...the white wires, it's calibrated to count pulses from the charging system in reference to RPMS.

SO...to put an aftermarket tach on our machines, you need to run a tap/lead from where the negative terminal is for one of the ignition/spark plug coils. It's been a while since I've talked about this, and can't remember whether you need to set the tach to1, 2 cyinder mode or 4 since we have 2 coils, but they fire on every rpm due to the wasted spark design?

I think some searches for aftermarket tach should reveal some more threads with the right info on selecting the settings.
T.C.

[DavesXS]

Thanks for responding,

I found some threads on it but nothing real conclusive. Nothing that says, "this is what you do" only " this is what you might try" and they never come back to the thread and say its done, and works great.

I can't figure out if I need a 4 cyl tach, or 2 cyl tach.

But when ever I do get it figured out I'LL post the results, and how its done for future searchers.

[oldman prof]

Hi Dave,I would like to try the same thing,but here in South Africa I have not yet found a 2cyl tach that does not run off a cable(I'm still looking),if you find out how to hook up a 4cyl one please let me know,if I find it first I'll post it.
Thanks
Anthony

[Pat Kelly]

<not a conclusive answer here, just a suggestion>

How about one of the wires going into one of the coils, gray or orange? They get a signal each revolution. The red/white wire from each coil ties together.
I would think you could then try either the 2 or the 4 cyl setting on the tach (I would guess 2 cyl).

This is where I would start if (and when) I install the SPORT VUE system on my bike(s).

[audijunky]

I have installed an aftermarket tach on mine. It was made for a V-twin and went up to 8k rpm. I get a bouncing needle on mine up to about 1500 rpm. After that it smooths out. I did what TC mentioned earlier tied the input to the negative side of the coil. Mine had 4 wires 2 were for the light in the tach(+12V the other ground), the other two were for the input signal and ground. Right now I can't remember if I tied it to both coils or just one. If I were you I would start out connecting it to 1 and see what the results are. If the RPMs are 1/2 what the should be tie in the other. That is how I started out but I am not sure if I had to use both coils or if 1 did the trick.
Good luck

[TupperJ]

Originally posted by audijunky
. If I were you I would start out connecting it to 1 and see what the results are. If the RPMs are 1/2 what the should be tie in the other. That is how I started out but I am not sure if I had to use both coils or if 1 did the trick.
Good luck

Was thinking about this is reference to a thread on another forum on a turn signal buzzer.

Would not a normal 4 cylinder tach work properly if it were tied to both coils through diodes? That way, the tach would see 4 pulses per revolution, and the coils would remain isolated from each other.

Just typing out loud.

Paul

[audijunky]

I dont believe (see disclaimer here) you could just hook it up to one coil if the tach were made for a 4 cylinder. If not I believe you would be fine without the diodes because you are connecting to the return line (ie ground) of the coil. I am not positive though, maybe someone can trace it out on a wiring diagram ,where the return line(or negative or ground) goes after the coil. if it just goes to ground , I see no problem hooking both up without diodes.
I also am just typing out loud

[TupperJ]

Originally posted by audijunky
I dont believe (see disclaimer here) you could just hook it up to one coil if the tach were made for a 4 cylinder. If not I believe you would be fine without the diodes because you are connecting to the return line (ie ground) of the coil. I am not positive though, maybe someone can trace it out on a wiring diagram ,where the return line(or negative or ground) goes after the coil. if it just goes to ground , I see no problem hooking both up without diodes.
I also am just typing out loud

Audijunky,

You got me thinking (Danger, danger Will Robinson!) so I looked at the wiring diagram. According the the Clymer version, the common wire appears to be hot all the time, while the gray and orange wires go to the TCI, which I assume would open each line to collapse the field in the coil and fire the plug. So, if the orange and gray wires are tied together, would opening one actually open circuit the coil, or would it still get power from the other wire?

Not sure. Having fun thinking it through though!

BTW, great choice in bikes, I just picked up an 84 Shadow 700. First Honda for me, all the rest of the bikes are Yamahas. I'm too tall for the bike, but my daughter should have a blast on it!

Ride safe!

Paul

[TopCatGr58]

Yes,

The negative side of the ignition coils ARE the gray/orange wires, but you would not want to link them because you would then be firing both coils at the same time twice as often!

You should only need to connect to 1 of them, and it won't really matter which one. The coils due to the wasted spark design fire EVERY revolution. A single cylinder engine fires once every 2 rpms.

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. Audijunky, I'm pretty sure you just connected it to 1 of your coils, or your bike wouldn't have run right if at all, and since the HD tach is looking for 2 pulses per 2 rpms, which equals 1 of our coils firing on every rpm!!!

Depending on some newer tachs and ignition systems of cars, they sometimes use 4 coils for 4 cylinders, each one only firing 1 time for 2 rpms vs. older cars that used 1 coil for all 4 cylinders, and then it fires 2 times per 1 rpm!!

Happy shopping!
T.C.

[audijunky]

TC is correct, I only connected to one coil. You all think it would work the same for a tach made for a 4 cylinder motor??