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ignition, single fire vs dual fire???

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Old 01-26-2011, 05:30 AM
emwolb emwolb is offline
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Default ignition, single fire vs dual fire???

what are the advantages of either system, and which system is idiot proof? also, is there a way to identify which system i have on my bike? it's not stock, but all aftermarket and i'd like to know what to look for, if i need to improve anything with the ignition system.
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Old 01-26-2011, 06:07 AM
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Hackd Hackd is offline
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I've been running a Dyna 2000, in dual fire mode, on my 93 FLHS since 2002. After a bunch of research, I didn't see much advantage in running it in single fire mode. Add in the addition of another coil (if used in single fire mode), I wanted to use the KISS approach on my bike. There are other, more significant, advantages to replacing the stock HD module with an aftermarket one. Namely rev limiting and ignition curve adjustability.

If you look at a dyno graph of most big twins, you will see that the stock ignition kicks off (limits) just as the EVO is building horsepower. Bumping the rev limiter up to 6000 will get you a fist full of (hidden) power for those occasional corner to corner romps.

IMHO, the whole wasted spark argument, is more of an advertising hype (on a stock compression EVO), than an advantage.
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Old 01-26-2011, 08:35 AM
V-Twins & Bowties V-Twins & Bowties is offline
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There is no difference IMHO. I had dual went to single did not notice a thing different.

The reason stockers have dual fire is as simple as lower cost in production.

They're both idiot proof until you get all fancy with the after market systems with numerous bells and whistles.

To ID, Dual fire the coil has two terminals. Single fire the coil has three terminals.
When changing coil/s pay attention to resistance value.

I run a Compufire single fire which is a set it forget it ignition. Its been in three years and so far not a problem.
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Last edited by V-Twins & Bowties; 01-26-2011 at 08:49 AM..
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Old 01-26-2011, 10:50 AM
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98 FLHX 98 FLHX is offline
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...Here's what Nightrider has to say about this topic....


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Old 01-26-2011, 06:42 PM
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t150vej t150vej is offline
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The only "real-time" advantages to aftermarket single-fire setups - they allow for different advance curves, dead cranking rev modifications and adjustable rev limiter settings, depending on the manufacturer. I run a single fire and it's of no advantage concerning mileage or power.
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Old 01-30-2011, 01:45 AM
emwolb emwolb is offline
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thanks for the replies guys. i just got a bike that has a compu fire box up between the front frame rails, and twin coils at 3 ohms each, and i'll pull off what we used to call the points cover to see what rotor is being used there. i can't see any advantage of a single fire over a twin fire, and the motor runs just fine. it's a new bike to me, so i'm trying to figure out what ignition it's using. thanks again.
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Old 01-30-2011, 09:24 AM
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PakMul PakMul is offline
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I put a Daytona Twin Tec single fire module and coil on my Ultra when the stock module died. It made no difference in the starting problem or the running of the bike. Nice to have the adjustable curves and all that since I've changed other parts of the engine since, but the single fire feature didn't really add up to much.
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Old 01-30-2011, 09:44 AM
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Stiggy Stiggy is offline
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If you've got twin coils at 3 ohms, you've got single fire. But like the other posts, there's not much practical advantage.
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Old 01-30-2011, 11:07 AM
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topfuel7 topfuel7 is offline
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I have the headquarters ignition and a Killer Watts coil. It has the dual or single option. It may depend on the setup of the bike or the igniton box itself because mine does idle different in single fire than in dual fire. I have to adjust the idle if switching between the two and it dosent spit back at all in single fire mode but it will occasionally cough back when in the dual fire mode.
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Old 01-30-2011, 11:07 AM

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