Author Topic: Hooking up a digital tach  (Read 8108 times)

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Offline Doggie

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Hooking up a digital tach
« on: March 05, 2015, 09:57:54 PM »
I'm hooking up a digital tach, and the manual says to hook it up to a ground and the negitive side of the coil.
(as on a car)  Where on the bike do I hook up the wires? Its a 1980 CB650C.
                               
                                                                                    Thanks, Doug

Offline Deltarider

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Re: Hooking up a digital tach
« Reply #1 on: March 05, 2015, 11:47:47 PM »
What do you mean, an electronic tach or a digital tach? In riding a digital tach is useless. It's always good to see the sweeping of the needle (the speed of that movement is also useful information), if only from the corner of your eye. A digital tach can't offer you that. It's just not intuitive.
If it's for diagnosis, have a look at the wire diagram of your model for the negative side. Usually it's the yellow or blue wire (just pick one). The black/white wire is the + wire. If I remember well, your model is equipped with a capacitive discharge ignition so the wires will not lead to contact breakers but to an electronic 'box' instead. But you will still need the blue or yellow wire. If you are going digital, be prepared for a disappointment. You will find a good dial with a needle is much easier to work with. Restless changing digits that you'll have to interprete every time will drive you crazy. Just my experience.
« Last Edit: March 06, 2015, 01:12:26 AM by Deltarider »
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Offline trueblue

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Re: Hooking up a digital tach
« Reply #2 on: March 06, 2015, 02:50:16 AM »
The negative side of one of the coils ;)
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Offline Deltarider

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Re: Hooking up a digital tach
« Reply #3 on: March 06, 2015, 07:54:12 AM »
Quote
Perhaps you need to broaden your horizons, Delta. Here's just one such instrument that is digital and does all the things you say. Even comes in 2 different models.  :o
No, I don't actually. I'm perfectly aware of all the toys and gadgets (the brand is motogadget sic!) that are on the market and offer us nothing we need and will distract us no end. But if you think it's useful to spend all that money on things you already have and spoil your vintage bike in the process, well... interesting. I have a different opinion. One of my first posts about instrumentation was exactly on how we can keep modern technique out of sight on our bikes so it won't spoil the looks. My own homebuilt transistor ignition module was nicely hidden behind a sidepanel.
The things you can sell to people with the words: digital, led, electronic...
Now, what is your problem? Maybe we can help.


« Last Edit: March 06, 2015, 08:21:39 AM by Deltarider »
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Offline strynboen

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Re: Hooking up a digital tach
« Reply #4 on: March 06, 2015, 09:16:37 AM »
classic analog instruments,,,for classic analoge motorcycels...if you are building a spaceship..the ´digitale are fine.but dont use it on road..you looses focus on road and trucks..and other heavy cast iron metal things :-[
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Offline Trad

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Re: Hooking up a digital tach
« Reply #5 on: March 06, 2015, 09:51:25 AM »
Well this might get interesting. I agree a bit on both sides to an extent but modern instrumentation is used on modern bikes and is not overly distracting. I don't get why things all of a sudden got so hasty. EASE UP!

If you want modern features thrown in on your vintage bike, all the power to you. If you want to keep everything era appropriate then that's awesome too. TO EACH THEIR OWN.
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Offline evanphi

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Re: Hooking up a digital tach
« Reply #6 on: March 06, 2015, 10:59:21 AM »
I love my digital speedo/tach combo. Does everything I need... gives me an exact tach readout PLUS a visual dial indicator, and speed of course.

There's a blue and yellow wire that connect to the aft end of the coils. That's where you want to attach your gauge's tach lead. Install the resistor in-line if your unit came with one.

Check the link in my sig for some tips if you also have an electronic speedo that hooks to your speedo drive.
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Offline Deltarider

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Re: Hooking up a digital tach
« Reply #7 on: March 06, 2015, 12:44:22 PM »
Quote
My reply, and product offered are a direct refute to your assertion that none such product exists, Delta.
First of all, I didn't make such an assertion. See above. Digital for me means representation in digits. That is quite logic, isn't it? What's the point in buying expensive digital stuff that then mimicks analogue representation? You might as well have stayed with the conventional analogue instruments IMO. You have to do without fancy blue lights but that's allright. They're not my taste anyway as most stuff from Taiwan isn't.
But now I come to think of it, maybe you just grabbed the opportunity to show your stuff. Well, congrats.
Am I opposed to new technics? Far from it. But I always prefer simple and intuitive above what I call show-of stuff. I've always regretted I donated my old analogue dwell/tach meter after I had bought a new digital one. The old set was much easier to work with. On the other side, that small Led voltage indicator Pewe showed for instance is a good example of what I mean. Direct, intuitive, simple and it beats all kinds of fancy gauges that distract us with digits our brain has to interpret.
But I must admit I find it hard to discuss with people that mount oil temperature dipsticks and pressure gauges at their feet because they 'like to know what goes on in the engine'. For heavens sake, when I'm riding, I like to know what goes on on the road. And what Honda thought what is useful for us riders to know, they've presented precisely in our line of sight. 
« Last Edit: March 06, 2015, 12:56:26 PM by Deltarider »
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Offline Doggie

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Re: Hooking up a digital tach
« Reply #8 on: March 06, 2015, 02:40:25 PM »
WOW!! I didn't know I would have started such a big discussion on this subject. I might have worded the question wrong. I bought a multi-meter that has a tach function on it. I want to set my air/fuel mixture screws
with the tach to get the highest rpm, since I have heard not to rely on the bikes tach. The manual shows an auto hookup like the old days (60's,70's) I was hoping to hook it up with the tank in place, maybe with the ignition cover off.
                                                                       Thanks, Doug

Offline chewbacca5000

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Re: Hooking up a digital tach
« Reply #9 on: March 06, 2015, 02:47:46 PM »
We'll the way I see it there is only one way to settle the digi - ano debate and that is at the track!  Delta vs Cal whose tac will win!  Now what should the minimum RPM be?  I say 10-5

Wobbly

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Re: Hooking up a digital tach
« Reply #10 on: March 06, 2015, 03:11:24 PM »
My other bike is a BMW RR. Its modern tachometer looks a lot like the one on my Honda. Hm,...

« Last Edit: March 06, 2015, 03:57:01 PM by Wobbly »

Offline Bailgang

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Re: Hooking up a digital tach
« Reply #11 on: March 06, 2015, 04:53:08 PM »
WOW!! I didn't know I would have started such a big discussion on this subject. I might have worded the question wrong. I bought a multi-meter that has a tach function on it. I want to set my air/fuel mixture screws
with the tach to get the highest rpm, since I have heard not to rely on the bikes tach. The manual shows an auto hookup like the old days (60's,70's) I was hoping to hook it up with the tank in place, maybe with the ignition cover off.
                                                                       Thanks, Doug

Oh now that's funny. Here some start flipping out over the use of a digital tach on a vintage bike when all you really wanted to know was how to hook one up for diagnostic/tune-up purposes only. Yeah it may have helped if you made that clear from the start but hey it was an amusing debate anyhow.
Scott


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Offline Killer Canary

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Re: Hooking up a digital tach
« Reply #12 on: March 06, 2015, 07:25:45 PM »
Without getting a ticket? I NEED to know your secret. ;D ;D ;D
If it's worth doing at all it's worth over-doing.
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Offline trueblue

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Re: Hooking up a digital tach
« Reply #13 on: March 07, 2015, 01:20:46 AM »
If you pop off the points plate you can connect to the wire that goes to the coil, that would be the easiest method.  ;D

I quite like my modern guages on my old bike ;D

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Offline PeWe

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Re: Hooking up a digital tach
« Reply #14 on: March 07, 2015, 02:28:08 AM »
My other bike is a BMW RR. Its modern tachometer looks a lot like the one on my Honda. Hm,...



K7 meters looks really good! I prefer a needle type speedometer when the angle of needle show speed instead of trying to see numbers. Manufacturers often change stuff only for provide something new, often not better.
Racing bike, no meaning of speedometer, tacho is enough. Street bike, speedometer very important.
I used my CB750 without tacho from 1982-1990. Long distance touring holidays without tacho. I heard when to shift.
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Wobbly

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Re: Hooking up a digital tach
« Reply #15 on: March 07, 2015, 03:06:36 AM »
Quote
...and its digital
No, the tachometer display is obviously analog and not digital although it's electronic. It's the only instrument that is not having a digital display, and perhaps for a good reason. I really think that there is some misunderstanding in this discussion. There was no objection to an electronic tachometer but to a digital one. By that, it is--to my understanding and that of some others--referred to a digital display of numbers which certainly wouldn't be useful. Good luck trying to make out these ever changing numbers for the rpms. So, we (hopefully) argue two different things here.
Anyway, you all have a great weekend with either a digital or analog display. I am off to the Alps with my bike (spring has arrived).

Offline 70CB750

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Re: Hooking up a digital tach
« Reply #16 on: March 07, 2015, 03:29:23 AM »
Ok guys, group hug   :D

Now for the real question; what oil do you use in your bike and why  ;D :D
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Offline Deltarider

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Re: Hooking up a digital tach
« Reply #17 on: March 09, 2015, 09:15:13 AM »
Quote
No, the tachometer display is obviously analog and not digital although it's electronic. It's the only instrument that is not having a digital display, and perhaps for a good reason. I really think that there is some misunderstanding in this discussion. There was no objection to an electronic tachometer but to a digital one.
Thank you Wobbly. Some folks just can't distinguish digital from electronic.
For all of you, just read back the way I informed Doggie in reply #1 just to help and to warn for too high expectations and then compare it to the sh.. hush hush .. load I got of non information.
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Offline wjustinleigh

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Re: Hooking up a digital tach
« Reply #18 on: March 09, 2015, 09:59:30 AM »
One definition of digital is representing information in numbers another is to represent information through binary digits which would include pixels on display (as well as digital broadcasts, digital images, etc).  Whether it's an actual needle, a picture of a needle, or a bar that goes up as a needle would, it seems like it would convey the same information to me.

It can also mean done with fingers (digits) which seems like a very inefficient way to track RPMs.

On the authenticity question, I have one cb500 with the original gauges and I love them.  I have another that was barely a cb500 when I found it with no original gauges or hardware so I stuck a digital tack (growing bar type) and speedo on there and love that too.  Looks nice tucked up under a small fairing and a lot easier to read at night.
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Offline mystic_1

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Re: Hooking up a digital tach
« Reply #19 on: March 09, 2015, 10:28:25 AM »
I'm hooking up a digital tach, and the manual says to hook it up to a ground and the negitive side of the coil.
(as on a car)  Where on the bike do I hook up the wires? Its a 1980 CB650C.

WOW!! I didn't know I would have started such a big discussion on this subject. I might have worded the question wrong. I bought a multi-meter that has a tach function on it. I want to set my air/fuel mixture screws
with the tach to get the highest rpm, since I have heard not to rely on the bikes tach. The manual shows an auto hookup like the old days (60's,70's) I was hoping to hook it up with the tank in place, maybe with the ignition cover off.


To actually answer the question being that is being asked here, Doug you should connect the negative multimeter lead to the frame ground, and then connect the other to either the Blue or Yellow wire at the coils.

Note that the ignitions on these bikes fire on both the compression stroke and the exhaust stroke, so an automotive-style meter will show double the actual RPM.  You can usually account for this by setting the meter to "2 cylinder" rather than "4 cylinder".  But, the fact is that for tune-up purposes, you're just looking for the highest value, so the actual numbers themselves are less relevant.

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Offline Deltarider

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Re: Hooking up a digital tach
« Reply #20 on: March 09, 2015, 11:59:22 AM »
Quote
I bought a multi-meter that has a tach function on it. I want to set my air/fuel mixture screws
with the tach to get the highest rpm.
This is theory and it will apply for many cars and bikes. But... although I'm not 100% sure about the 650, I wouldn't recommend this practice for our CB's and certainly not for the CB500/550. If you have achieved the highest idle by adjusting the airscrews, you will experience the bike, allthough it purs like a kitten, will not accelerate well anymore. Better just set the airscrews by the manual.
« Last Edit: March 09, 2015, 12:05:05 PM by Deltarider »
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Offline wjustinleigh

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Re: Hooking up a digital tach
« Reply #21 on: March 09, 2015, 12:24:57 PM »
That's because of the difference in mix on the slow/main jets right?  If you were optimal at idle you'll be lean/rich when accelerating.  You'd need electronic fuel injection and a power commander to be efficient all the way up.  Doesn't it also run a little rich at idle to help keep it cooler while sitting in traffic?
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Offline strynboen

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Re: Hooking up a digital tach
« Reply #22 on: March 09, 2015, 12:27:35 PM »
yes fuel are cooling..so more fuel make it run" kooler"..lean make pistons burn/melt..by the ritch oxygen%and less fuel..
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Offline Deltarider

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Re: Hooking up a digital tach
« Reply #23 on: March 09, 2015, 12:42:09 PM »
Quote
Digital and Analog both rely on electronic sources. Lesson over.
Alas, not for you, I'm afraid.
Somewhere in the basement I have a digital clock that is electric and not electronic. So digital is not necessarily electronic. And analog (or analogue) is not necessarily electronic in my book. But let's not split hairs. I'm glad you're happy with your gadgets, blue lights and all.
But why don't you and all your energy move to another post I just wrote (CB550 heartbeat) about balancing carbs. I count on you, you know. ;D
Please, I'm not good in English, what or who is Moron? You spelled it with a capital, so I take it you have much respect. Is he your God?
« Last Edit: March 09, 2015, 12:53:07 PM by Deltarider »
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Offline wjustinleigh

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Re: Hooking up a digital tach
« Reply #24 on: March 09, 2015, 02:06:04 PM »
Not to prolong the digital/analog dialog, but I believe you can have a mechanical analog system which would not be electronic.  I believe the tach would be one of those systems.  In which case analog could be either electronic or mechanical.
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