Single-Fire or Dual-Fire ignition?

[GregInMesa]

2011 Honda Shadow Aero VT750C

Can someone please tell me if my bike has a Single-Fire or Dual-Fire ignition?


Thanks

[Snow Shadow]

I'm not shure what bike you own- two plugs per cylinder = Duel fire I believe.

[C.W.]

You have two plugs per cylinder, and they both fire at the same time. That's because both plugs (for the same cylinder) fire from a single coil. That's how it shows in the wiring diagram in a 2005 shop manual. So, you got 2 coils, 1 for each cylinder.

Two plugs make a faster burn requiring less spark advance.

That's how I learned it.

Laters, C.W.

[byggd]

If i'm not mistaken the Shadow fires on both compression and exhaust strokes. Some call it a wasted spark system.

[GregInMesa]

So is that Dual or single?

so far it's Dual-fire:4 Single-Fire:2

My Honda Dealer Service guy told me Dual-fire and Honda America said he "thinks" it's Single-Fire.

All I know is I bought a Tachometer, installed it and it reads 1/2 the RPM's
i.e. idling at 500 and so on. to me that says single-fire.

I can't find anyone who knows "For sure" yet.

I am trying my hardest to not use an adaptor and have to rewire it again I already have the front coil Neg going into the headlight with a lead and have already tapped into the power and lights.

Bikers Choice only sells dual-fire Tachs according to their Tech support (or Tach support lol).

I ain't buying nothin' until I know for absolute God's honest sure if the 2011 Honda Shadow Aero VT750C (Fuel injected) is single-fire or dual-fire ignition.

Remember, I got a 1/2 reading using a Dual-Fire Tach.

Thinking of just hiring a Midget to sit on my carrier rack and count the tire
revolutions and calculate the RPM's for me.

[nraluke]

This is a bikers choice mini tack installed on my 08 Aer0 750. Its dual fire.

[C.W.]

If I'm not mistaken, by single fire you mean one spark (both plugs at same time) for every 4 stroke cycle, then yes, it's single fire. I don't see how it can be any other way after looking at the wiring diagram. Both plugs are wired to one coil, so if it is dual spark, then it has to be with both plugs firing both times in the 4 stroke process.

Laters, C.W.

[GregInMesa]

When the Person at Honda America told me he thought it was a Single-Fire ignition he said because on page 1-5 of the service manual (2011-2012) it says "Firing order Font - 308 degrees Rear 412 degrees"

Which to him meant the Coils fire each cylinder once per cycle so therefore
its a single-fire ignition. (I corrected this quote line)

Then there is the post just above yours (nraLuke) where he installed a Bikers Choice
Tach for a Dual-fire on a 2008 Honda Shadow Aero VT750 and it worked fine without having to use an adapter. But he wired his differently than I did. He went to the rear coil, I went to the front coil. He tapped into the ignition Wire, I tapped into the headlight fog light option wires for both the power and the Ignition On. I combined the ignition lead and power lead on the Tach and connected it to the Fog light option power (+) wire which is "Switched" as well and the ground to the foglight option ground wire. Is the 2008 Dual and the 2011 Single???

I got this wiring from how Cobra wires their Tachs.

I doubt it makes any difference if you wire to the Front or Rear Coil.

But on the Dual-fire ignition sytle Tach I was getting a 1/2 RPM reading,
exactly 1/2 of what it should be, no fluctuation, lights worked fine, just 1/2 of actual RPM's. This is a symptom of a Dual-fire ignition Tach being used on a single-fire ingniton System I have read in a couple places.

Again, I want to make Darn sure what I have before I do anything else at this point. Trying to avoid using the Tach Adapter for 2 reasons. 1. already have everything wired so I can get at it from the headlight area
without taking off the gas tank again. 2. I read that you get some fluctuation in the needle using the adapter.

Hiring that Midget is sounding pretty good to me now ... lol

[corvin]

[QUOTE=byggd;1310121]If i'm not mistaken the Shadow fires on both compression and exhaust strokes. Some call it a wasted spark system.[/QUOTE
That is correct about dual fire.
Regarding to reading of half from the real rpms your bike is single fir.
The gauge reading the sparks.So if you have a gauge for dual fire,youre bike single fire the reading are half from the real rpms.
Just my tought.

[GregInMesa]

Here's the tally so far; Dual-Fire: 5 Single-Fire: 4



I found this when I googled it today:




"People get this mixed up all the time. The number of spark plugs or ignition coils used has nothing to do with single fire or dual fire. Our bikes use two spark plugs powered by a single ignition coil, per cylinder. But this does not indicate if it's single or dual fire.

• Single fire means the spark plugs ignite only once, which happens roughly during the beginning of the combustion stroke. (Once per every 4 strokes)

• Dual fire means the spark plugs ignite once during the combustion stroke and once during the exhaust stroke. (Twice per every 4 strokes)

Dual fire systems don't provide any more power so there is no advantage, it was just the most simple way to run the mechanical ignition system used on older engines like early Harleys before electronic ignition control was being used. If your bike is using an electronic ignition control system, as all modern bikes seem to, then it's safe to say it's a single fire system. Some electronically controlled systems in automobiles fire during the exhaust stroke to help burn up any remaining unused fuel but this is merely for pollution control purposes. Since motorcycles don't even have catalytic converters I don't see why they would bother using dual fire for this purpose.

I know for a fact that all Shadow Spirit/ACE 750 models from 2001 to 2007 (non-shaft) are dual spark plug, single fire systems. I don't see why the C2 model would be any different."

that came from here: http://www.shadowriders.net/forums/s...ad.php?t=18868


but then there is still NRALuke above with the 2008 Honda Shadow Aero VT750 haunting me with the BC Dual-Fire Tach that worked without an adapter.

Does anyone know a reliable Midget with great eyesight???