I did it on my RT1 in 'rat bike' race trim cheap MX'r. I'd do it differently nowdays but had a Harley twin lead coil so i guess it was a battery DC coil & only a points mag. Had to have the plug gaps just about closed to jump spark. It ran & i melted the piston big time haha. Melted down the front, not a hole in the top. Gave up on that idea. But i'd try it again now with cdi. Two source coils & triggers plus 2 boxes. Need a stator plate with two coils exactly opposed on the plate. Maybe two triggers exactly opposed is more important--for timing anyway.

Doesnt need 2 source coils. Simply a dual lead HT coil. Dual spark ignition, is something that is used on many modern factory team off-road bikes.

I expect modern bikes that use this arrangement have primary source power designed to fire a dual output HT coil?

You can't get something from nothing...  so wouldn't a dual output spark coil need a magneto capable of more primary power (2X more?) to reliably fire a two output coil?

I have a twin spark TY175 CDI ignition. Sparks jump about 10mm, source coil is exactly the same as single spark system.

Likewise, factory YZ465 MX bikes, had dual spark systems, other than the twin lead coil, rest of the system stock.

Very easy and cheap way to get improved performance from any CDI equipped bike.

Not sure if it would work well if the CDI is very old though, as capacitors degrade over time, and might have trouble firing 2 plugs.............

Got told about dual fire CDI systems years ago, by a guy who makes ignitions for XR69s and Indy cars, as well as TZs and pretty much all serious competition bikes.

He used to be an F1 engine builder, and one of his 2T systems fitted to a Rotax go-kart motor, gave it about 4hp extra.

Love to have a link to study a twin spark systyem.
I'd like to try a system like that sometime but sounds too easy.
Be good to have a link to the system you use on the TY175.
I googling away but found nothing that relates to how i'm thinking--one box--one source coil & one trigger coil plus one 'twin plug lead' coil with a single wire in from the cdi box.
I'm thinking much like Mark says--ya get nothing for nothing.
Keen to learn.

It seems to me if you split two leads off of a system designed for one spark plug, you're going to end up with two weaker sparks. On the other hand, what about if there was a way to alternate between the two spark plugs? Could that help to reduce creating hot spots on the piston? Now I'll put away my can o' worms opener 

Twin-spark systems work very well. I have a video of my TY dual spark system being bench tested by the manufacturer, but dont have high hopes of being able to find it!

The idea of twin spark on these bikes has been around at least as long Yamaha added a second 14mm hole in the head for that late 60's, early 1970's two stroke fad, the cable operated compression release that made a neat "braaaaap" sound and slowed the bike down when you pulled the lever.

.Nissan implemented twin spark plugs on their late 70's "NAPS-Z"  (Nissan Anti Pollution System) "Z" series iteration of the earlier venerable L16-L18-L20 B engine series.The USA got the NAPS-Z in the early 1980's.  As the name implies, the twin spark plugs per cylinder were for emissions reduction...  in this case Nissan used lean air/fuel mixtures combined with a massive amount of EGR (exhaust gas recirculation) and pretty much needed two plugs to double the chances the weak, diluted mixture would fire at all.  It was a well-designed and engineered complete package...  (they didn't just add an extra spark plug to an existing engine design and magically reduce emissions and increase economy...  those were the main benefits... horsepower was not really improved over earlier single plug versions).

The modern high output Chrysler Hemi V8 also has two spark plugs per cylinder...  again, for emissions.  One plug fires normally on the compression stroke.  The second plug fires on the exhaust stroke to ignite any leftover fuel in the exhaust.  I asked a friend about this and he said that there are kits to fire both plugs on the compression stroke but they reduce spark energy by firing both plugs from one coil.  He said you can find a lot of info in the forums and that even the "Hellcat" version only fires one plug on the compression stroke even though it could fire two, yet some people still modify the ignition to fire both plugs and swear by it.  (I have not researched those forums)

He reminded me that "colliding flame fronts" are the main factor that creates the sharp, damaging pressure spike known as detonation...  and that by firing two plugs you were creating "competing" flame fronts which logically would increase the chance of detonation?   So maybe that's why it's not commonly used?

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Back when I was a kid at the local races some two stroke racers were experimenting with dual spark plugs...  they modified the magneto and were using just the points to trigger a battery ignition. (had to charge/swap the battery between heats) Some had cut the flywheel down to just a points cam.  (talk about light flywheel!)   A few years later when I was racing myself, those systems were nowhere to be seen.  Twin plugs simply didn't stand the test of time. 

The Champion Spark Plug rep gave me some info and I think it was Jennings in his seminal "Two Stroke Tuner's Handbook" that said basically the same thing.  A poor ignition system can lose power because the engine doesn't make any power if the mixture doesn't ignite.  But all you need is "good enough".  Even an ignition system that somehow harnessed God's own lightning simply cannot give you any more power than the engine already had in it.  The Champion rep specifically told me that OEM ignitions were really good and that "better spark" modifications were a waste of time and money unless you were running on the edge...  like top fuel drag racing that ran fuels, boost, and compression ratios that required very high energy to even create a spark under those conditions. 

We were watching an old "wild west" movie last night and it included a scene where the "Snake Oil Salesman" (see en.wikipedia.org/wiki/Snake_oil for those not familiar with this term) drove his wagon into town peddling a "cure all" elixir.  I thought about some of the recent posts on here and laughed a little as I realized things haven't changed all that much.

Here in Yama-land (as Asco calls it), the wagon has recently shown up with "Nibbi carbs" and "twin spark systems" painted on the side. 

I don't mean any disrespect to any members with that observation!  There is a difference...  I don't believe anyone here is deliberately trying to deceive or scam anyone.  I can't even begin to name the number of ideas I've come up with and/or heard of and believed in over my life that turned out to be "snake oil" in the long run. 

My guess is at least some "cure-all" elixir salespeople, past and present, truly believe in the product they are selling.  The problem is believing something doesn't make it the truth.  And now that I'm older, as much as I want to believe some of these claims, I tend to approach them with a more "agnostic" approach.  Just because something sounds good and completely logical, I realize I don't know nearly as much as I thought I did so I'm not so quick to believe anymore. 

Even science has had that problem.... some pretty crazy things used to be thought of as "scientific facts".  Time and more experiments often comes back with the conclusion that the more we learn, the more we realize we really don't know much of anything.

There's one thing about the truth.  The truth doesn't need a "cheerleader"...  it is just the truth. 

My thought process on this "twin spark" is if it was so good...  and if Yamaha could have gained HP and performance by using a twin spark system by simply adding a twin plug coil with existing source coils (they already had twin plug heads), why didn't they?  

What a crazy wonderful world we live in! 







 

 

Very good analogy Mark T.
I owned one of the Nissan NAPZ trucks… in 4wheel drive up here, on a road covered with snow, had to keep the RPM’s up, in a lower gear. It just didn’t prove to preform in my eyes…
And now I have a Ram truck… almost time to change plugs. All 16!
Sneezles61

>>And now I have a Ram truck… almost time to change plugs. All 16!
Sneezles61<<

I have a 2018 Ram, but with the 3.7 Pentastar V6 and 8 speed trans. Only 6 spark plugs, and the oil filter is on top of the engine with easy access. Catalytic converters are also tucked up in the engine compartment, and hard to steal. It really is a great engine, and peppy with the 8 speed, but for heavy towing you want the Hemi.