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While working on my fuel injection project, I did a lot of research on coils. My blue 1980 GS1000 had become difficult to start, and the coils and wires looked to be originals. I tested the coils and plug caps and found one of each was out of spec. OEM specs for the coils are 3~5 ohms primary and 31~33 K ohms secondary (plug cap to plug cap). I found inexpensive aftermarket coils by Emgo, but could not find much in the way of reviews. The Emgo PN I used is 24-37810, and they are listed in the Emgo catalog for use with Honda models that use electronic ignitions. Emgo makes a KZ/GS coil PN 24-72451 but it is listed as being for the older points ignition models only. The points style GS lists primary resistance as 2~6 ohms and secondary as 11~17 K ohms. Here's a pic from the Emgo filter/mirror catalog:
The NGK plug caps contain 5 K ohm resistors and are available in several angles. I used 2x XB05F and 2x VB05F. I bought the coils and caps from vendor possum-0607 on eBay for $85 shipped. Since I wanted to get everything from one vendor and they do not advertise the caps, I had to special order them and they sent me a Paypal invoice. It took about a week to get everything from Tennessee.
I found an Emgo Honda replacement coil that is rated as 2.5 ohms- the OEM GS electronic ignition coils are 3~5 ohms. While I did not find much info for them, apparently the company has been making replacement parts for a long time- I think the aftermarket mufflers on this bike are from Emgo. One nice thing about the coils is that you can replace the plug wires using any 7mm wires. You use the NGK resistor caps on the other ends.
When I tested them out of the box, I got these readings:
Primary: 2.5~2.6 ohms
Secondary: 14.3 K ohms
The coils have rubber seals that fit under the nuts to seal the coils. Installing a plug wire is easy. You put the nut over the wire, then slide the rubber seal over the wire (a little water as lube helps), and then thread the wire into the coil's terminal. Push the seal up tight and then tighten the nut. The plug caps are similar, each has a rubber boot for each end. You place the boot on the cut-to-length wire, then thread the cap onto the wire, and slide the boot over the end of the cap.
They mount the same way as OEM coils and have an identical 102mm bolt spacing. I found my GS had both 90 and 102mm brackets on the frame rail. I reused the GS bolts, spacers, and nuts. The plug wires exit to the rear, and this places the primary terminals to the front. I cut off the old coil primary wiring with connector and crimp/soldered some .250 terminals, which I then covered with some heavy gauge heat shrink. It was a tight fit for the outer plug wire nuts to the frame tube, but they do not rub. If you wanted a little more room, you could shorten the spacers. I bent down the primary terminals so I could reinstall the tank. I was working with a nearly full (heavy) tank, so bending the terminals may not have been 100% necessary.
Once installed, I got 2.8 ohms primary and 32~33K secondary (plug cap to plug cap). It had been hard starting, but that is no more, it lights off right away with just a bump of the starter. In my experience, these are a cost-saving alternative to other aftermarket coils.
I did not take any pics of this as it was a fairly straightforward install that was completed in one afternoon.
The NGK plug caps contain 5 K ohm resistors and are available in several angles. I used 2x XB05F and 2x VB05F. I bought the coils and caps from vendor possum-0607 on eBay for $85 shipped. Since I wanted to get everything from one vendor and they do not advertise the caps, I had to special order them and they sent me a Paypal invoice. It took about a week to get everything from Tennessee.
I found an Emgo Honda replacement coil that is rated as 2.5 ohms- the OEM GS electronic ignition coils are 3~5 ohms. While I did not find much info for them, apparently the company has been making replacement parts for a long time- I think the aftermarket mufflers on this bike are from Emgo. One nice thing about the coils is that you can replace the plug wires using any 7mm wires. You use the NGK resistor caps on the other ends.
When I tested them out of the box, I got these readings:
Primary: 2.5~2.6 ohms
Secondary: 14.3 K ohms
The coils have rubber seals that fit under the nuts to seal the coils. Installing a plug wire is easy. You put the nut over the wire, then slide the rubber seal over the wire (a little water as lube helps), and then thread the wire into the coil's terminal. Push the seal up tight and then tighten the nut. The plug caps are similar, each has a rubber boot for each end. You place the boot on the cut-to-length wire, then thread the cap onto the wire, and slide the boot over the end of the cap.
They mount the same way as OEM coils and have an identical 102mm bolt spacing. I found my GS had both 90 and 102mm brackets on the frame rail. I reused the GS bolts, spacers, and nuts. The plug wires exit to the rear, and this places the primary terminals to the front. I cut off the old coil primary wiring with connector and crimp/soldered some .250 terminals, which I then covered with some heavy gauge heat shrink. It was a tight fit for the outer plug wire nuts to the frame tube, but they do not rub. If you wanted a little more room, you could shorten the spacers. I bent down the primary terminals so I could reinstall the tank. I was working with a nearly full (heavy) tank, so bending the terminals may not have been 100% necessary.
Once installed, I got 2.8 ohms primary and 32~33K secondary (plug cap to plug cap). It had been hard starting, but that is no more, it lights off right away with just a bump of the starter. In my experience, these are a cost-saving alternative to other aftermarket coils.
I did not take any pics of this as it was a fairly straightforward install that was completed in one afternoon.