could someone explain to me about dual fire and single fire coils and what would be a good set up for a hot thunderstorm motor? im running 2 plug heads so have found that dyna tec do a dual plug coil but is single fire. everydays a school day huh!

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BUELL-Turning riders into mechanics since 1983!!!

One fires two plugs at once and the other one individually. My S1 fires both at once.

I get mixed up with the names, does single fire fire both plugs at once, i.e. Once per crank rev? Or does single fire do a single fire per cylinder per cycle?

I think 45 deg V angle is close enough to not need individual firing...

Your twin plug heads will be interesting, you should be able to shave off a lot of advance and you will probably need to otherwise it will knock like buggery...

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08 Specialized Langster

in the old days it was easy
coil per cylinder that would fire once at end of compression stroke
then they reduced number of coils and paired cylinder together 1+4 and 2+3
and we had what i would call lost or wasted spark, now coil fires every time piston reached top of stroke TDC ( or a few deg before ) the lost or wasted spark being on the paired cylinder that's on the change from exhaust to induction so no load (pressure/resistance to the spark)

now as for a v twin thats a big bang type set up (not 180 deg between power stroke's )
as pash say
I think 45 deg V angle is close enough to not need individual firing...

Your twin plug heads will be interesting, you should be able to shave off a lot of advance and you will probably need to otherwise it will knock like buggery...

cos IF i am right the wasted lost spark will now be arriving part way on the compression stroke??
i have just googled dynatek and they do do a twin cylinder duel spark plug per head coil its Dynatek DC6-4
do hope this helps a bit

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Buell Ulysses XB12X 06/08

Front wasted spark will come on the exhaust stroke rear wasted spark will come at very early induction.

NRHS concluded there is no difference:

http://www.nrhsperformance.com/tech_singlefire.shtml

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08 Specialized Langster

good find pash

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Buell Ulysses XB12X 06/08

PM Steely,he runs a Dyna twin plug single fire set up,with impressive results.As anyone that has done a track day with him will testify.

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Drinking Rum before noon makes you a Pirate ! Not an alchoholic.

is it possible to run two coils for now untill i get the single twin plug coil?

thanks for the input pash and team . had to read it a couple of times but im getting my head round it

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BUELL-Turning riders into mechanics since 1983!!!

I fitted twin DC1-1 coils rather than the four-post DC6-4 coil, on a twin plug / single fire setup, with the Dynatek D2Ki-P ignition module. With twin plugs, I would definitely recommend getting the programming kit. The bike ran ok on stock curves available using the switches on the module, but working out a curve to suit the twin plugs has made a huge difference in smoothness and pickup.

This is on a Sportster, by the way... details here:

http://xlforum.net/vbportal/forums/show ... ?t=1382357

Dual-Fire:
Fires both plugs at the same time

Single-Fire:
Fires each plug individually

While not much performance gain is noticed with a single-fire, you get longer life and better reliability out of your ignition components; they're firing half as often. When running a modified engine with higher compression or modified ignition curves, you do notice a difference. Seeing as my Ultima is single or dual fire, I tried it on dual fire. It fell on its face when I would go WOT, no fun, single-fire it is.

Ultima sells an ignition that is a direct clone of the Dynatek 2ki for cheaper; it even uses the Dynatek software for programming. I, and others, use the Ultima with success on our Blasts.

This is what I got: p/n 53-660


This is where I got it. (Jireh Cycles)

If the Dynatek can be used for dual-plug single-fire, the Ultima can as well.

jet, if i use the ultima kit i would still need to buy another coil (4 plug leads dont forget)

Its looking more like a dyntek as they are great to deal with and very helpful when i emailed them.

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BUELL-Turning riders into mechanics since 1983!!!

How many cut outs are there on the Blast rotor?

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08 Specialized Langster

Check on e-bay. List price for the D2Ki-3P kit that I have (with twin DC1-1 coils) is $399.99, but they can be had for around $312. I bought through ATV Galaxy, who were good to deal with.
These prices do not include the programming kit, which is about $90 extra.

You can use an ECM and programme with ECMSpy

I got my Dyna 2000 from ATV Galaxy.

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08 Specialized Langster

I got my Ultima to my door for $166. It is identical to a Dynatek 2ki unit, compared at my buddies Harley shop. I can set it for single fire mode, then connect the front/rear leads each to their own dual-fire coil and have double sparks for each head in single-fire mode. I hope that makes sense.

The Blast rotor has one cut-out, but I re-indexed the twin-cup (that came with the ignition) for use on the XB-indexed cams. I'm using the single-fire coil with the plug wire for the rear cylinder grounded to the rear shock mount.

You can download the software for free from Dynatek.co.uk and I can make the interface adapter myself (I've made 1 for myself and 2 for friends, all work perfectly).

I wonder if I could set it to dual-fire mode, double-plug my single head, use a single-notched rotor, and basically have a single-fire double-plugged single? Probably just easier to get a dual-fire coil and leave the rear spark plug wire grounded. [/brainstorm]

With a single cutout, the ignition must think it is running at half speed as there is only one pulse. Can you account for that in your ignition map?

Would be interested to know why dual fire didn't work. That would allow you to get rid of the earth to the rear coil... But you could do that by not connecting the rear output from the ignition unit.

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08 Specialized Langster