ingnition pulses

[dodgediesel59]

Ok guys I am going to try to get my autometer on and working this weekend but for some reason am having a very hard time understanding the whole ignition pulses thing. So our bikes have a "dual fire" ignition which means it fires once on compression and once on exhaust stroke for each cylinder right? So that would mean per one crank rotation you would get one pulse? On the install instructions with the tach it says that the way it sees thing a 4 cylinder car engine has 2 pulses per engine revolution which I would guess is one turn of the crank as well? I basically need to know what I can do here. KJshover was going to try using a pulse doubler which you take signal from 2 coils and run through diodes and resistors to create double the pulses. I guess I am looking for some input on understanding things and figuring out what I need to do. Thanks in advance.

 

[bazwell]

I could answer this, if I knew what settings the Autometer has.

When they say a 4 cyl has 2 pulses per engine revolution, they are talking about a 4 cylinder with a single coil and a distributor. A 4 cylinder with coil packs will fire each coil once every 2nd revolution. A four cylinder with coil packs which run waste spark will fire one coil each revolution.

So, what settings does the Autometer have?

 

[dodgediesel59]

The autometer has 4 6 and 8 cylinder settings. I greatly appreciate any help you can give me!

 

[bazwell]

Somebody else should check this!

A 4 cylinder car (with a distributor and one coil) will fire all 4 cylinders every 2 revs, so 2 pulses per rev. in total.

A v-max fires each coil every revolution (waste spark), so 1 pulse per rev. in total.

So, (like what KJ Shover said), you will have to double the number of pulses, or it will only read 50%.
To do this, you need to connect the Autometer to 2 coils. One has to be from the front bank (2 or 4), and one from the rear bank (1 or 3).
They need to have diodes fitted to stop the coils firing at the wrong time.
(Then you can set the Autometer to 4cyl.)

Most of what you need is in this webpage --> http://www.gadgetjq.com/tach_install.htm

I'm not sure why this person used resistors in their solution. Just leave them out!


Like this :



Hope this helps!

 

[[email protected]]

I had exchanged some emails with autometer about this awhile back. They told me that if I send it in, they could change something inside the tach to make it work for 2 cylinders. I've heard some guys have had issues with the diode trick on the coils. I've heard some guys say it works just fine?

Here is my correspondence with autometer. Start at the bottom and go up.

On Mon, 1/18/10, Joseph Mills <[email protected]> wrote:

From: Joseph Mills <[email protected]>
Subject: RE: Auto Meter Sales FAQ Form
To:
Date: Monday, January 18, 2010, 12:43 PM

Hi Mike,




This typically costs around $35 or so depending on the revision of the circuit board in the unit..

Thanks!

Joseph

​

From:
Sent: Monday, January 18, 2010 11:40 AM
To: Joseph Mills
Subject: RE: Auto Meter Sales FAQ Form


Thanks for the quick response. My ignition is not magneto so we should be good there. A sunpro works fine in my situation set to 2 cylinder mode but the quality and looks are not there. I like the looks of your product but you don't have 2 cylinder mode.



So, if I buy it and send it in to have set up to 2 cylinder mode, do I have to pay to have that done?

--- On Mon, 1/18/10, Joseph Mills <[email protected]> wrote:

From: Joseph Mills <[email protected]>
Subject: RE: Auto Meter Sales FAQ Form
To:
Date: Monday, January 18, 2010, 12:26 PMHi Mike,

That tach will not function out of the box on a two cylinder application. We can however modify the unit for you for 2 cylinder calibration. This has to be done after purchase as an item sent to our service department. Please be aware that we do not warranty our automotive tachs for motorcycle/powersports installations and many cylinder automotive applications use magneto style ignitions which are not compatible. Our address here is:

Auto Meter Products
Attn: Service
413 W. Elm St .
Sycamore , IL 60178

Please be sure to include a note with your contact information and a description of the problem. One of our techs will contact you once they have had the opportunity to inspect the unit. Hope this helps, please let me know if I can be of further assistance.

Best regards,

Joseph Mills
AutoMeter Products, Inc.

-----Original Message-----
From: Auto Meter Website [mailto:[email protected]]
Sent: Monday, January 18, 2010 11:23 AM
To: [email protected]
Subject: Auto Meter Sales FAQ Form

**************************************
* Auto Meter FAQ Question Submission *
**************************************

Date Submitted: Monday, January 18, 2010
Type: Sales
Department: High Performance
From: MIke Baker
Email: [email protected]
Vehicle Make: Other
Vehicle Model: Other
Vehicle Trim: custom
Vehicle Year: 0
Vehicle VIN (8th Digit):
Product Model No. :
Gauge Series: Phantom II
Gauge Type: N/A
Question(s):

I'm looking to purchase a Phantom II 5" tach. Part # 7599. I had a few questions prior to purchasing though. #1 and most important to me are the cylinder settings. I want to install it on a 2 cylinder motor but this tach, or most any other that I like the looks of, is for 4,6,or 8 cylinders only. I have heard that it is possible to change resistors inside the tachometer to acheive the proper reading. Can you provide any insight?

​