Author Topic: In my dreams... electronic tach  (Read 8155 times)

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Offline ev0lve

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In my dreams... electronic tach
« on: March 15, 2010, 05:16:43 am »
I've got a GL1000 frontend I'm going to graft onto my 750 here this summer and I keep poking at having a single gauge setup trying to keep the profile as flat as possible. Nothing's decided of course but...

I'm looking at this 5" APC tach (minus the shift light) and wondering if it's a good idea. Says 4, 6, 8 cylinder and it's triggered off of the ignition so "should" be accurate. There's a lot I don't know so any pitfalls to a setup like this? Anyone done it?

« Last Edit: March 17, 2010, 04:25:17 pm by Iggy »

Offline cosmo

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Offline Gregorymoto

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Re: In my dreams...
« Reply #2 on: March 15, 2010, 10:21:04 am »
It should hook up just like a shift light. I dont see why it would not work.
Yep, i have issues with this sort of stuff.


Offline ev0lve

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Re: In my dreams...
« Reply #4 on: March 17, 2010, 04:24:02 pm »
OK. Wait. On a 750 both coils fire regardless of which is actually going to explode some fuel. Won't a signal from one coil be enough to drive the tach accurately since it fires on compression and exhaust?

"Needless to say the factory tachometer just doesn't cut it and installing an electronic tachometer will only read the pulses from 1 coil so the reading is cut in half."

What am I not understanding about why that fellow did what he did? Unless I've got seriously bad information about what the coils are actually doing?



Edit: Off a post on Nabble
"See the issue you will have is with the wasted spark system, everything is going to read it as a 2 banger. And so you need to compensate."

Hmmm


I think I get it. Firing 1 - 4 and 2 - 3 you're not getting pulses for half despite firing on every compression stroke - it's only the firing of 2 pistons. 1 - 4 are offset from 2 - 3. This fellow is just feeding in the signal for both. Uhhhh, duh  ;D
« Last Edit: March 17, 2010, 04:53:35 pm by Iggy »

Offline ev0lve

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Re: In my dreams... electronic tach
« Reply #5 on: March 17, 2010, 05:20:08 pm »
Good enough info in that PDF it seems like it should be on site somewhere so here it is:

Electronic Tachometer Adapter

As most of us figure out at some point the factory tachometer on most older bikes isn't very accurate at low speeds and tune up time becomes an impossible task trying to adjust the carburetors or anything else that requires reasonable accuracy. On my CB750 the idle speed is specified to be ±100rpm, choke speed ±200 rpm and the pilot adjustment you have to look for a change of 50 rpm or less! Needless to say the factory tachometer just doesn't cut it and installing an electronic tachometer will only read the pulses from 1 coil so the reading is cut in half. Having a tach-dwell meter left over from prehistoric days I decided to find a way to utilize it on the dual coil system. Below is the circuit I came up with to adapt the dual coil circuit to use an electronic tachometer.



R1 can be any ¼ watt or larger 10k resistor. D1 and D2 can be any 4000 series diode. The two diodes form a simple and gate which will allow each coil to trigger the tachometer without interfering with the other coils operation. Although I marked the leads to the coils for coil 1,4 and coil 2,3 it really doesn't matter which wire goes to which coil as long as they go to the – side of the coil. I used an alligator clip for the battery connection and soldered together a male and female butt connector to make the coil connections.

© Jerry Rotert 5-2009

Update: I received a few questions about the hookup do here are a few pix. Hopefully this will clarify some things.



For the splice I started with a male and a female butt connector and spliced them as shown. The wire in the right picture goes one of the diodes. You will need two or three of these splices depending on your application. Note: I actually removed the blue insulators and soldered the connections for durability but they can also be crimped if you wish.



Here is the connector on the left coil. You will need another on the right side. The pix on right shows the complete cable that I made. The 2 diodes and the resistor are inside the shrink tube. The 2 yellow wires marked coil go to the diodes in the schematic. The purple wire goes to the tachometer and the red wire goes to the battery. Someone ask about making it permanent for a regular tachometer. In that case you would of coarse want to make the wires as short as possible and connect the battery wire to a switched connection. This could be done by making a third “tap” and connecting to the + side of one of the coils. Since I just made it as a tune up aid I used an alligator clip.

Note: you can make the wires any color you want. I just had these colors handy. The 2 yellow wires go the the – side of the coils. The red wire goes to the battery or optionally to the + side of one coil. The purple wire goes to the tachometer. The ground wire from the tachometer connects to any good ground.


Offline Laminar

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Re: In my dreams... electronic tach
« Reply #6 on: July 12, 2010, 01:01:15 pm »
Iggy:
Are you using the stock points? If so, what type of tach are you using?

Offline ev0lve

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Re: In my dreams... electronic tach
« Reply #7 on: July 12, 2010, 01:09:29 pm »
Decided to go with a stock GL1000 tach (eventually it won't be stock  ;D ) and a bike speedometer at this point.

And that's not my getup if there's any confusion - the fellow buried the info in a PDF. I posted it here so it would be searchable.

Offline Laminar

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Re: In my dreams... electronic tach
« Reply #8 on: July 12, 2010, 02:45:32 pm »
So the GL1000 tach is electronic and works with points?

Offline ev0lve

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Re: In my dreams... electronic tach
« Reply #9 on: July 12, 2010, 06:13:13 pm »
So the GL1000 tach is electronic and works with points?

No  ;D

Offline gnarlycharlie4u

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Re: In my dreams... electronic tach
« Reply #10 on: July 13, 2010, 08:36:33 am »
Electronic Tachometer Adapter...

wow that's genius. gj

here's my solution: (since i'm getting an electronic ignition anyway)
Dyna 2000
"There are also 2 user programmable RPM outputs that can be used to activate a shift light or other RPM activated device."

Dynoman has 'em cheap.


edit: fixed
« Last Edit: July 16, 2010, 11:33:20 am by gnarlycharlie4u »

Offline ev0lve

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Re: In my dreams... electronic tach
« Reply #11 on: July 13, 2010, 08:43:50 am »
Electronic Tachometer Adapter...

wow that's genius. gj

here's my solution: (since i'm getting an electronic ignition anyway)
http://www.dynaonline.com/skins/products/sportbikes/dyna_2000/
Dyna 2000

"There are also 2 user programmable RPM outputs that can be used to activate a shift light or other RPM activated device."

http://www.dynoman.net/ignition/dyna2000.html
Dynoman has 'em cheap.


We might disagree on the definition of cheap  ;) Eventually (it's always eventually) I'm thinking I'll go with a Hondaman ignition - which is cheap by any definition.

Originally I just wanted a single gauge setup and was thinking of just the tach - changed my mind on that front once I saw cornandp's getup.
« Last Edit: July 13, 2010, 08:48:23 am by Iggy »

Offline The_Crippler

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Re: In my dreams... electronic tach
« Reply #12 on: July 13, 2010, 08:45:56 am »
Can you try those links again, gnarlycharlie4u?  They don't seem to be working right now.

Offline ev0lve

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Re: In my dreams... electronic tach
« Reply #13 on: July 13, 2010, 08:47:19 am »
Can you try those links again, gnarlycharlie4u?  They don't seem to be working right now.

They're just doubled up - look at the URL and pull the quotes and extra http:// out.

Fixed them in the quote

Offline gnarlycharlie4u

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Re: In my dreams... electronic tach
« Reply #14 on: July 16, 2010, 11:34:37 am »
sorry i fixed the linx.

but yea cheap by comparison (+free wires :D)
I have the Hondaman now and it works fine. I'm still itchin' to go points-less though

Offline 73nancy

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Re: In my dreams... electronic tach
« Reply #15 on: July 16, 2010, 03:16:11 pm »
so if you have a electronic ignition with no points how hard is it to wire up a electronic tach then. does anyone have the link to the member hwo put a bike speedo in a tach thats was pretty slick i would like to do the same but with a electronic tach
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Offline Laminar

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Re: In my dreams... electronic tach
« Reply #16 on: July 16, 2010, 03:24:58 pm »
so if you have a electronic ignition with no points how hard is it to wire up a electronic tach then. does anyone have the link to the member hwo put a bike speedo in a tach thats was pretty slick i would like to do the same but with a electronic tach

Apparently it's a piece of cake. Ground, +12V, and one of the signal wires from the coil.

You're looking for cornandp's build: here.

Details on how the speedo and tach are integrated is here at the SuperHawk forum.