Dyna coils

[James England]

Hi everyone. I realise this subject has been covered in previous thread(s) but, because the info in a thread tends to come in bit by bit in a long string, I'd like to post this one to ask for confirmation that I've understood correctly. So here goes:

If your bike has OEM coils and ballast resistor, with mechanical and vacuum auto advance and you want to change the coils to green 3 ohm Dyna coils, you do the following. Mount the coils on the bike using small L brackets or whatever. Connect the low tension wires from the wiring loom to the Dyna coils. BYPASS the ballast resistor by disconnecting the bullet connectors from it and joining them together. Connect HT leads to each coil. Left coil (orange low tension wire) goes to cylinders 1 and 4 and the right coil (grey low tension wire) goes to cylinders 2 and 3.

And that's it, right? The 3 ohm coils will not damage the TCI unit...... correct?

Or have I missed anything?

[DGXSER]

you Got it. Lots of Folks running 3 ohm coils w allast resistor byassed and no tci trouble.

[natemoen]

Correct. No damage will be caused to the tci.

Mount, rewire, bypass rresistor, and GO!

[DAVINCI]

You got it, James, to the letter.

Damn, you guys type fast

[natemoen]

Correct. No damage will be caused to the tci.

Mount, rewire, bypass rresistor, and GO!

[natemoen]

How did my response get posted twice, 15 min apart?

[petejw]

just to add,
the dyno coils will have a + and a - side.
the red/white wires go to the positive side
and the blue/orange wires go to the neg
side of the corresponding coil.

[James England]

just to add,
the dyno coils will have a + and a - side.
the red/white wires go to the positive side
and the blue/orange wires go to the neg
side of the corresponding coil.

Actually, the dual output Dyna coils (ie with outlets for 2 HT leads) don't have any particular polarity. The low tension wires can go on either of connectors on each coil. The polarity of the low tension wires is only important for the single output version.

[petejw]

fair enuff,
im running mikesxs coils,
they have a neg and pos,
thought the dyna's might be the same.

[James England]

fair enuff,
im running mikesxs coils,
they have a neg and pos,
thought the dyna's might be the same.

No. I appreciate your previous posting though, as it's always best to be sure and you could have saved me blowing up some expensive kit. I was puzzled at first, then found a little leaflet in the box that said it doesn't matter on the twin output Dynas. You're absolutely right though for the single output ones. They have to be connected correctly or they immediately burn out............ better to be safe than sure.

[DAVINCI]

What's in them that would burn out if connected backwards?

[James England]

What's in them that would burn out if connected backwards?

I don't know..... it's what it says on the leaflet . I always thought it was just a low tension coil and therefore immaterial which way it was connected (must be that on the dual output coils) but for the single output coils, polarity is, according to the blurb very important with risk of damage if incorrectly connected. Maybe there's a diode, resistor, thingy or something in there for the single output coils? Dunno. Good job we aren't running four single output coils in a line.....

[DAVINCI]

A diode or resistor wouldn't be a factor. In fact, a diode would prevent it from working at all if the polarity was reversed, but it wouldn't burn up. Interesting.

[crazy steve]

Coil polarity...

Coil polarity is important on a single-tower coil because you want the high voltage to go the 'right' way. With a dual-tower coil, both sides of the high voltage winding go to plugs, and there's no connection to the low voltage coil. On a single tower coil, both the high and low voltage coils have a common connection; the negative terminal, or ground. If you connect it backwards, the spark voltage flows the 'wrong' way and this connection will fail as it's not designed to take kilovolt voltages.

[cywelchjr]

Coil polarity is important on a single-tower coil because you want the high voltage to go the 'right' way. With a dual-tower coil, both sides of the high voltage winding go to plugs, and there's no connection to the low voltage coil. On a single tower coil, both the high and low voltage coils have a common connection; the negative terminal, or ground. If you connect it backwards, the spark voltage flows the 'wrong' way and this connection will fail as it's not designed to take kilovolt voltages.

Ummm, it's still an electrical circuit, and everything MUST flow through the entire path. There is no way for a working electrical circuit to do anything else and still actually work. That said, I suspect it's to do with the fact that the outer casing, frame connection is probably the ground, and that might be a problem, but any coils for our bikes (and most vehicles for that matter) have both sides of the primary coil isolated from ground (at least in a TCI setup) as the voltage comes in one end, and goes to the TCI on the other which alternately makes and breaks a ground connection on that side, so their CAN'T be any interconnection between the primary and secondary there. However, if there is an internal capacitor in there, incorrect polarity COULD cause a problem and blow it if it's an electrolytic, although I would be surprised if there was one.