Dyna coils

[DAVINCI]

If you're talking about an autotransformer, you'd still be wrong

[cywelchjr]

If you're talking about an autotransformer, you'd still be wrong

It helps when you reply to a post to put enough context (especially when you say someone is wrong) so people can tell who your talking to. Transformers (which is what spark plugs coils actually are) are essentially AC devices (pulsed DC is in essence AC, just without the reversal of direction) and have no inherent polarity. That said, under a pulsed DC setup, sometimes a capacitor is used on the input side to clean the feedback from it's own magnetic field collapsing from the circuits before the coil/transformer, and these often have a polarity which can cause the overall circuit to have a polarity to it, even though the coil itself doesn't have any polarity.

[DAVINCI]

Capacitors? Condensers? Where are you going? We don't have them in our systems.

[petejw]

we've already established im no electrical guru, lol
mikes black xs coils have the polarity stamped on them
so in essence does it not matter which way they are connected?

[crazy steve]

Uhhhh... I think you both misunderstood my explanation or I didn't get it clear enough...

Most two-tower, dual fire coils have no polarity. I'll go a step further and define what this is; the XS coils have two completely separate coils in them (primary/secondary, or low voltage/high voltage), wrapped around a common core (a transformer, as Cy said). There is no electrical connection between the coils other than the EMF generated by 'switching' the primary power. This type of coil can be identified by having two connections for the primary ignition system and two connections for spark plugs, and always fires both connected plugs at once. If you check with a multimeter, you'll find continuity between the two primary connections and between the two secondary connections (to the plugs). You should not have any continuity between any primary/secondary connections, or to the case/ground. If you get current flow both directions between the two primary connections (no diode) this is a 'non-polarized' coil. If whatever you have meters out this way (even if the primary connections are marked + and -), it's non-polarized.

A polarized coil will only have three connections (or five, if it's a two plug single-fire). It will have a positive connection for the primary (+) and a negative connection (-), also for the primary. But for the secondary, you only have one accessible connection; the one that goes to the plug. The other end of this coil is also connected to the primary negative connection. So here, you do have continuity between the positive, negative, and plug connection, but still none to the case/ground. Here, which way the primary wires are hooked up do make a difference. The negative connection is always connected to either the points or the ignition box, and this is the switched ground path. Hook it up backwards, and you'll subject the primary coil winding to the same voltage as the secondary and quickly burn it up. You could do this with a points ignition and the motor would still run (at least a while..); I suspect if you did this with an electronic unit it would smoke the box in a matter of minutes, if not seconds....

[James England]

I got the Dyna coils installed. It's really is easy to fit them using four L shaped brackets. They're actually smaller than the OEM coils and they go straight in with no problem at all. They're a nice, tidy fit:








I used silicone leads with a carbon core. The bike fired up immediately. No smoke from the TCI!

[natemoen]

Glad ya got them in without hassle!

[James England]

Glad ya got them in without hassle!

Thanks!

I've not had the chance to take the bike out as it's still wet and cold here with salt still on the roads from all the snow we had. But, the bike definitely starts better. It's noticeably better on start up. Will report back once I take the bike out on the road........

Here's a question...... if the ballast resistor fails on the standard system (for the earlier bikes, that is), then does the ignition stop working? Or does it continue to work and fry the TCI??

[bikerphil]

Here's a question...... if the ballast resistor fails on the standard system (for the earlier bikes, that is), then does the ignition stop working? Or does it continue to work and fry the TCI??

If the ballast goes bad, the tell tale sign is the engine will fire only when the starter button is pushed (ballast being bypassed at that point) and once released, engine will die. I don't think any damage will occur to the TCI if the ballast fails, the engine will just quit, no spark.

[DAVINCI]

Coil polarity

Found some interesting writings about this subject. Curiously none that describe reverse-polarity 'burn-up'

[crazy steve]

Found some interesting writings about this subject. Curiously none that describe reverse-polarity 'burn-up'...

While these articles are mostly accurate, there's a few errors that inevitably creep in when a layman attempts to explain real-world operation without fully understanding electrical theory, as well as failing to note a few other details.

Coil 'burn-up' is a real phenomenom. Put simply, it's caused by the way inductive circuits work. An inductive circuit is trying to do a certain type of 'work'; it may be firing a plug, it may be turning an armature in a motor, but if presented with conditions that prevent it from operating as designed, it will just draw more current until it can do the 'work' or at least try to. This is the same effect that causes a worn starter or one with poor connections to draw excessive current. In this case, reversing polarity will reduce output (as was noted), but the coil will draw more current in an attempt to bring output up so it can 'do the work'. Due to other circuit limitations, it doesn't make it but the side effect is a smoked coil...

DAVINCI, you say you've 'been around' since '69, 'diagnosing' engines. Surely you remember the tune-up scopes of the day, all of which displayed dwell, spark energy, and coil polarity. If the 'spike' was above the line, polarity was good; below the line, it was reversed and you were directed to correct that before going further. As a tune-up tech, you didn't really need to know 'why/how', just that for proper operation that's what it is.

To fully understand this, you would need to take a full course in AC theory; I doubt if cherrypicking a few articles off the net will do it.

[DAVINCI]

If the 'spike' was above the line, polarity was good; below the line, it was reversed and you were directed to correct that before going further.

But the engine would still run

To fully understand this, you would need to take a full course in AC theory;

How do you know I haven't have you?

I've never seen it happen, so until I do, I reject your theory.

[crazy steve]

[I]How do you know I haven't have you?

I've never seen it happen, so until I do, I reject your theory.

I know you haven't because I have taken the course; I taught the course for several years too. At the time of my early retirement (due to a back back), I had a unlimited electricians license as well as holding a electrical administrators license. I don't have a degree in electrical engineering, but it wouldn't have been too much of a stretch to get one...

If you want to attempt to educate yourself on this, I'd recommend reading/studying 'Electricity One-Seven', Harry Mileaf Editor, and 'Electricity for Electricians' by Abraham Marcus to get the basics. Your algebra and trigonometry better be up to snuff as this is very math-heavy; also buy a good scientific calculator. These books may be out of print, but I'm sure your local library or college bookstore could fix you up with equivalents.

[DAVINCI]

Well, there's theory and then there's practice. Luckily we don't need to know how to build an airplane to take a vacation, eh?

[James England]

Well, regardless of the theory or whatever, the people that make the coils say that they will be damaged (for single output ones) if incorrectly connected, so that's good enough for me. I'll take their word for it.