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I have a question that I would love to hear an honest/qualified answer to.. I purchased a dual coil setup from a guy here on chop cult, he told me that I can use this setup with my points ignition, but now people keep telling me that you have to have an electronic ignition to run a dual coil setup.. So now I just don't know what to believe... can someone educate me on this a little?? Thanks
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It won't fire them INDEPENDENTLY with one set of points, but it should fire them since points are just a mechanical switch. They might draw a few more amps but points are cheap to replace if they wear early.
Two coils on one points set will act electrically as one coil firing "wasted spark" just like a stock setup.
Why did you want two coils? In future, post questions before buying parts. The seller may have been happy with them fired together, but you should study ignition theory before choosing an ignition.
Wasted spark theory of operation. A twin would fire one dual pole coil.
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You can, but be aware of primary side coil resistance. Points like around 5 ohms of resistance. Less will shorten their life. Read the resistance with an ohm meter, and wire them accordingly. In series will result in the sum of the resistance of both, parallel will result in half the resistance of each. I'm pretty sure they have to be wired in series not to be too low in value.
BobComment
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Yes it is a 1983 fxrt motor, i was told it would work with my points setup, but will buy a different one of need be. This is basically what I'm trying to figure out.. (If I need to buy a new points setup?, or electronic ignition).. The coils only have one spark plug wire output each, so no need for 4 plugs, if I could send pictures I would it I can't figure out howComment
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What coils are they? Dynatek? Is there a number on them? DC-(x)? The type of coils make a difference.
First off, the topic of single fire/dual fire here is irrelevant (as far as whether it will work). The stock Harley setup was dual fire. The points have a single mechanical switch to fire the coil(s) at the same time. It fires at two intervals (one for each cylinder). This means that when the points fire the coil to send spark at the correct time for the front cylinder, it also sends spark to the rear cylinder while it is on it's exhaust stroke and vice versa. This is what is known as "wasted spark" as the spark plugs will fire on both the compression and exhaust strokes in both cylinders (ie... "dual fire"). Again, while this isn't optimal, it is how the stock system was designed and it has been working for decades. If you're using points, you are using a dual fire system. There are "electronic" (fully digital, or electro-magnetic like a Dyna S) which come in single fire variants (the Dyna S comes in single or dual fire version). This fires the spark plug(s) for each cylinder independently (i.e... "single fire"). In any case, you have selected a points ignition, so you've by default selected a dual-fire setup. Moving on...
Will points work with dual coils? Yes. The coils do matter though. For a street bike, a 5 ohm coil is what is recommended. For a race bike, a 3 ohm coil is what is recommended (theoretical hotter spark). For dual coil setups, (2) 1.5 ohm coils wired in series are the recommended setup. You're probably adding the 1.5 ohm + 1.5 ohm and saying, that's only 3 ohm's... isn't that only recommended for race bikes? The answer is no, at least when it comes to Dynatek coils. Per them, their 1.5 ohm coils are 6v coils which work on 6v or 12v setups. Due to their design and some complexities related to timing and how the coils are used in a v-twin setup, using (2) 1.5 ohm coils wired in series will generate hotter spark without substantially increasing the amperage draw. This is why Dyna recommends (2) 1.5 ohm coils in series for STREET setups when going dual plug head (separate topic). In any case there are intricacies here when comparing coils that are "true 12v coils" vs coils that were designed for a 6 or 12v setup. I've had a discussion with Dyna's lead engineer about using (2) 2.2 ohm coils wired in series (4.4 ohm total) vs (2) 1.5 ohm and based on the above, he told me the (2) 1.5's will not draw any extra amperage based on the fact that the 2.2 ohm coils are true 12v coils vs the 1.5's which are 6v/12v and that they recommend the (2) 1.5 ohm coils wired in series for a hotter spark.
That was a lot of info but sometimes additional context helps.
Cliff's notes: Yes it will work. (2) 1.5ohm Dynatek coils wired in series. Find out exactly what coils you have (should have a model number on it).
One question for you though: while it will work, why do you want to run two separate single post coils, vs a single 5 ohm coil w/ 2 posts?Last edited by boomboomthump; 06-28-2016, 8:24 AM.Comment
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'cause that's what he has in his garage, I bet.
I'll add to the confusion and "point" out that dual point, single fire setups were available for a while there. Kinda fiddly to adjust but they were neat. I ran one in my dual plugged shovel, till I picked up a 2000i.Comment
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I do already have the setup, that's why I'm trying to make sure it's going to work ok.. (I get a lot of different opinions from different people down here in Roswell, got to the point where I was stressed about it, figured I'd reach out to you guys on here for some knowledge.. So far I've learned a lot, thanksComment
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