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emerald island igniton coil

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wa1nca
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emerald island igniton coil

Post by wa1nca »

What is the difference in the black and blue emerald island coils ?
Tommy
Last edited by wa1nca on Sun Dec 04, 2022 7:48 pm, edited 1 time in total.
Tommy Byrnes
54 R51/3, 55 R50/Velorex 560 sidecar, 64 R27, 68 R69US, 75 R75/6
Ashfield, Ma
USA

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vechorik1373
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Re: emerald island igniton coil

Post by vechorik1373 »

Bench Mark Works first imported them.
After quite a few failures of the first black version, we discovered that the internal ground wire, (which was soldered to the steel bar inside) would come loose, and the coil instantly died.
On second black version, I told the manufacturer, to bring the ground wire OUT and put an open lug on it, so it would ground under the screw that holds the clip on the drivers side. Reliability improved enormously. I guaranteed them for one year, unlike the rewound originals out of Europe that have NO guarantee. The only problem with the black ones, was that the enameled copper wire was slightly larger in diameter, which meant there were not as many turns as the originals. Which made a slightly weaker spark at kick start speeds, but they worked.
The third and current version (with smaller gauge enameled copper wire, and many more turns of wire) I specified for them to make them a different color, so I could tell them apart from the earlier versions when I had the rare occasion to warranty one.
All of these coils are epoxy potted by modern vacuum methods to prevent the swelling and chafing of the enamel insulation from repeated heating and cooling.

What causes the original coils to fail is the copper windings swell when hot, touch each other, then cools and shrinks when the engine cools down, and eventually it wears the enamel insulation off the copper, and then when the get hot, they short part of the winding out, and if you try to start the engine again, while hot, you will have no spark (because you have less than 10,000 turns of wire when shorted out) until it cools completely down.
Vech
Technical Adviser, Former owner, Bench Mark Works
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mcsherry1328
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Re: emerald island igniton coil

Post by mcsherry1328 »

Vech, Thanks for the in depth reply and thorough explanation of the coils. That answers a lot of questions. Always appreciate your tribal knowledge on vintage bikes and components.

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wa1nca
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Re: emerald island igniton coil

Post by wa1nca »

Always great info:
Thanks Vech
Tommy
Tommy Byrnes
54 R51/3, 55 R50/Velorex 560 sidecar, 64 R27, 68 R69US, 75 R75/6
Ashfield, Ma
USA

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