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Discussion Starter · #1 ·
I want to connect a SportVue Heads Up Display (HUD) to my 99 M900S. This bike did not come with a tach and my question is..........Is there a wire that I can use as a good tach signal input for the SportVue. In otherwords, for those of you that have hooked up a tach to your bikes that didn't come with one, which wire did you use for the ignition signal?
 

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Depends on the tach... You can tap into one of the wires in the ignition modules. I believe the colors you want are either the gray one or the brown one. They will be in the 3 pin connectors. Do not mess with the wires (red/wht or blk/yel) in the 2 pin connectors!

That may work. It's what DP uses for their tach kits that last 3 months. :) :mad: ;D

;D Chris
 

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Discussion Starter · #3 ·
Got it. Thanks Chris. I'll let you know how it turns out.
 

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chris said:
Depends on the tach... You can tap into one of the wires in the ignition modules. I believe the colors you want are either the gray one or the brown one. They will be in the 3 pin connectors. Do not mess with the wires (red/wht or blk/yel) in the 2 pin connectors!

That may work. It's what DP uses for their tach kits that last 3 months. :) :mad: ;D

;D Chris
Chris is right. I just want to add that the carbed 900s use a waste spark. The tach in question may read double the actual rpm.
 

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+1 on Chris. Grey-signal, red-power, black-ground in the 3pin to ign unit.
 

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Discussion Starter · #6 ·
Anyways the HUD doesn't like the tach signal. It wont' measure the rpms and seems to throw the other settings (speed, gear, shift) out of whack. I have a call into SportVue but could someone elaborate on the waste spark/ double rpm that ducpainter mentioned.

Here is a description of what I've done and the results. I used the grey (middle wire on R ignition module) and I'm getting some crazy readings on the HUD. I tested this signal with a hand held digital tach/dwell that I have for cars. When set to 4 cyl mode (lowest it has) the meter reads a steady 59 at idle (sorry i'm not sure what the multiplication factor for the meter is. x-nothing, x10, x100?) and increases as expected with more throttle.

ASSuming that 59 is actually 590 rpm, wouldn't 4 cyl mode on a 2 cyl engine read double the actual rpm because it's receiving twice as many signals as it expects. If so this means my actual reading is more like 300rpm. That can't be right. Do I have this bAss ackwards?
 

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J_C said:
Anyways the HUD doesn't like the tach signal. It wont' measure the rpms and seems to throw the other settings (speed, gear, shift) out of whack. I have a call into SportVue but could someone elaborate on the waste spark/ double rpm that ducpainter mentioned.

Here is a description of what I've done and the results. I used the grey (middle wire on R ignition module) and I'm getting some crazy readings on the HUD. I tested this signal with a hand held digital tach/dwell that I have for cars. When set to 4 cyl mode (lowest it has) the meter reads a steady 59 at idle (sorry i'm not sure what the multiplication factor for the meter is. x-nothing, x10, x100?) and increases as expected with more throttle.

ASSuming that 59 is actually 590 rpm, wouldn't 4 cyl mode on a 2 cyl engine read double the actual rpm because it's receiving twice as many signals as it expects. If so this means my actual reading is more like 300rpm. That can't be right. Do I have this bAss ackwards?
Yes you do have it backwards. 4 cyl mode will read half of 2 cyl. So your 590 reading is actually 1180.

Is there a setting on the display for 2 cyl?
 

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Discussion Starter · #8 ·
No 4, 6, or 8 only.

I figured it was another case of me and the dumb ass. Thanks for the clarification.

Can you expand on the waste spark comment?
 

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J_C said:
No 4, 6, or 8 only.

I figured it was another case of me and the dumb ass. Thanks for the clarification.

Can you expand on the waste spark comment?
The carbed Monsters fire twice for every cycle. I don't know why. When I installed my SPA tach I had to set it for a 2 cyl because of it.

Basically it fires on compression and again on the exhaust stroke, hence "waste spark". In effect it makes the device, in your case the HUD, think the ignition is operating twice as many cylinders.

AFAIK there is no other place to pick up a signal other than the ignition module, or the wire from the pick up itself.
 

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ducpainter said:
The carbed Monsters fire twice for every cycle. I don't know why.
'cause it's easy - they just run a magnet on the flywheel, and a pair of hall effect sensors (90 degrees apart) in the sidecover. That means you get sparks at both TDC's, so it sparks between the exhaust and the inlet stroke as well as between the compression and ignition stroke, but that "wasted" spark doesn't bother anything, and you'd need to run some sort of sensor on the valve gear if you want to make the sparks fire only every second rotation - with the low tech carbed bikes, why would you bother?

big
 

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bigiain said:
that "wasted" spark doesn't bother anything, and you'd need to run some sort of sensor on the valve gear if you want to make the sparks fire only every second rotation - with the low tech carbed bikes, why would you bother?
Coils get more "charge" time when there isn't a wasted spark. I forget the term the Dyna coils engineer used, but I liken it to charge time.
 

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chris said:
Coils get more "charge" time when there isn't a wasted spark. I forget the term the Dyna coils engineer used, but I liken it to charge time.
Potential?
 

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ducpainter said:
chris said:
Coils get more "charge" time when there isn't a wasted spark. I forget the term the Dyna coils engineer used, but I liken it to charge time.
Potential?
I think "dwell" is the term - it used to refer to how many degrees of engine rotation the points stayed shut back in the days of mechanical points switching the ignition... There days with hall sensors and electronic ignition it doesn't really have much of its original meaning left...

big
 

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bigiain said:
Potential?


I think "dwell" is the term - it used to refer to how many degrees of engine rotation the points stayed shut back in the days of mechanical points switching the ignition... There days with hall sensors and electronic ignition it doesn't really have much of its original meaning left...

big
Yeah, that's the word, but like Big said, it's not really relevent these days; not only in definition, but also in function. The more modern ignition systems don't need the dwell time to develop full spark. So like it was said before, the waste spark doesn't hurt anything but it sure does save dollars, and headache when troubleshooting the ignition.
 

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A.Duc.H.Duc. said:
Yeah, that's the word, but like Big said, it's not really relevent these days; not only in definition, but also in function. The more modern ignition systems don't need the dwell time to develop full spark. So like it was said before, the waste spark doesn't hurt anything but it sure does save dollars, and headache when troubleshooting the ignition.
How so? Has coil technology kept up? I would think that a coil would still need a certain length of time to charge fully. If you make that same coil fire twice it has half the time to reach its full potential.

Isn't that the reason Chris sells the dyna coils? Better/hotter spark?

Keep in mind I'm asking, not arguing
 

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We're both right. Sure a single spark engine would be able to put out more spark, and sure aftermarket coils can help put out more spark. But modern solid state electonic ignitions, as opposed to points ignitions develop more than enough spark for OEM needs with only half of the dwell time.

The point is Ducati, or any manufacturer for that measure, can use a wasted spark ignition system and have the ignition perform right where they want it to perform, so why engineer more garbage to tell the ignition system to only spark on the appropriate stroke? It's not really a best case ignition system, it's just a perfectly adequate ignition system.

Justin
 

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bigiain said:
I think "dwell" is the term - it used to refer to how many degrees of engine rotation the points stayed shut back in the days of mechanical points switching the ignition... There days with hall sensors and electronic ignition it doesn't really have much of its original meaning left...
No, I'm pretty sure the terminology he used wasn't dwell. This engineer actually has a Duc 900ss and is familiar with the carby ignition system. The concept was that of recovery time or time between firing to build energy in the inductance of the transformer core. I'm and EE and everything he said made sense. IE, nothing he said sounded like BS or snake oil. He said we could use their new coils but we'd then have to also have 2W resistors inline with the coil to knock down the current and not blow up the ignition modules. :p Well, that's no good; huge resistors aren't elegant.

The same engineer said the green dyna coils (3 Ohm) are better than the black ones (5 Ohm) above 5000 rpm, but the green ones are hard on the charging system. So we compromise and go with the black. I use the black 5 ohm coils on Pongo and they worked killer, so I'm pretty happy with their performance.

:)
Chris
 
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