Low cost OEM replica coils.

Don't know how long these have been available. These are a low-cost, made in Taiwan, replica of the Kawasaki (oem: TEC) electronic ignition coils.
classiccycleparts.com/index.php/kawasaki...00-kz1300-z1-kz.html

I think they may sometimes be labeled as Emgos. The Sku is 24-37810.
You can find the same coils for sale as Honda replacements. There are quite a few listed on ebay.

I just installed them on my Gpz550, and my buddy installed them on his Kz550.

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Some slight differences:
The mounting holes are slightly smaller so you cannot use the brass inserts used on the factory coils. I'm not sure what the inserts were for in the first place. Most coils can be mounted with a steel bolt right through the core (as is done on Dyna's and Accel's). The holes are 102mm apart and line up with the frame just fine. You can use the factory bolts and brass spacers without any issue.

You have to use 8mm wires. The factory wires were 7mm, so you will need new wires. New wires are usually the plan for most people anyway.

The rubber grommet is tight but does fit. Get an allen head bolt that measures a little over 8mm. Put it in a vice. Then use the dielectric grease that comes with the wires to slide the grommet over the bolt head. Then press the wire up to the bolt head and transfer the grommet to the wire. It goes on easy, even though the grommet looks too small.

There are no markings on the coil except the "+" and "-", which are still a mystery as it is on the factory coils too. I use the polarity, even though I don't see why it would matter.

The advertised coil specs are slightly different than the OEM coils, but the measured specs are actually closer to the OEM specs.
Primary is 2.3 ohms, like the factory.
Secondary is 14k ohms. Factory were spec'd at 13K.

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I used 8mm Accel suppression wire, available at most auto parts store as a generic kit for v-8 cars. You can make 4 sets with that kit.
So far, both bikes runs great with no ignition hiccups. I think my 35 year old coils were ok, so these didn't really improve anything. My buddy's coils were misfiring, so these really made a huge improvement on his bike.
He's had them for about a week. I've had them for one day so far.

I will probably try to get another one and stress test is on the bench to see how it really holds up against my old factory coils.

You can't go wrong with replacing 35 year old coils. Just replaced my 550 coils with Kawasaki 21121-1035 and 1036, which are still available, currently $71.89 each from Partszilla.com. They are a slightly different design from the originals, but still made by TEC and include the factory spark plug wires.

I will probably try to get another one and stress test is on the bench to see how it really holds up against my old factory coils.

Drop test, interesting...what do you use for that?

Domestic / commercial electrics uses a 'megga' to stress test circuits.

This is what I use to test coils for actual spark.
kzrider.com/forum/21-tools/561376-true-c...l=component&type=raw

Nice to know the TEC coils are still available. I shocked (get it) that the old 35 year coils worked as well as they did. I've kept them totally dry for 9 years now, but experience tells me they are a good rain storm away from going belly up.

If these knockoffs don't measure up, I'll seek out the TEC coils for sure.

The Z1 coils were 5 ohm. I've used KZ 1000 ST coils and they don't fit the mounts. Too long. There are many sellers on eBay that claim their products will fit but if you'll notice there is always a disclaimer in their ad. eBay will do nothing to stop these dishonest practices.
Steve

Z1 sold the EMGO four Ohm replacement coils with new wires molded in for the steal price of $36. I have been running one for about eight years.

Bad news is, nobody carries them anymore.

www.z1enterprises.com/ItemDetails.aspx?i...zuki&item=EM24-72451

That figures.
Steve

Nice work Lou, a coil testing simulator, similar to the simple 'two nails in a a block of wood' test procedure but with your oscillator electrickery. I guess simulating the decreasing dwell angle at higher rpms as the spark gap increases,

I always thought the 'irony' of ignition systems being the decreasing dwell angle/rpm relationship: when you need the fattest spark at high rpm you get the weakest spark, and vice versa.

My only question being , you are checking increasing spark voltage against reducing dwell angle as rpm increases? -just what the bike sees... but how about chucking 1000 Volts Dc plus through those coils and checking insulation resistance like a 'megger' does? i.e. simulating 30 years later heat cycling and insulator resistance breakdown. This is where a 'megga' would come in handy , but totally unknown/unused it seems to auto electricians.

On a personal note Lou, I noticed over 10 years ago you were one of the smartest techs on the GPz550 forum., I appreciate your analytical skills very much - one of the few in the world that seems to properly understand these machines. keep it coming

Thanks for the compliment Brendan. :blush:

Actually I test them multiple ways. I hit them with high constant dwell at high RPMs and with normal diminishing dwell at high RPMs. The latter simulates the bike's dwell to see how the coil does with that, and the former to see what the coil can actually do given optimum dwell. I have several test rigs. That one in the video, I think is the constant dwell version.

Hitting it with max dwell, and a long spark gap, does in fact stress the coil to somewhere over 600 volts on the primary side (as well as the igniter). But then you are getting close to permanent damage on both units, so I only go for broke when I want to test to failure. I suppose some may reach near 1000v, but that's hard to measure because the spike is so brief. Even though the igniter has a safety bleed-off circuit (Zeners), the spike is so sudden, the zeners can't react fast enough to relieve the voltage so the spike ends up higher than the Zener rating.

Sometimes it's the coil that fails, sometimes it's the igniter... depending on condition, quality, design parameters etc. etc. When the coil fails, it's usually the secondary side with high-voltage leaks. Usually that coil will test ok if it only failed briefly, but in the long run, it will be intermittent at higher RPMs and higher throttle... simulating a carb issue. When the igniter fails it's the primary sides ability to withstand the primary spike (300 to 600v). Then the coil energy just dissipates through the igniter as a short.

A buddy of mine has extra NOS of Ergo 4.2 OHM coils that he used on his Triumph... Would they work on my 79/650B3 that calls for a primary winding of 3.2-4.8 Ohm? The same spec holds for all 77-79 KZ650's.

I'm confused knowing some folks are using Dyna 3.0 and others 5.0. I'm running points. A good explanation would help. thanks

They should work but can be harder on the points.
Steve

No eBay APP ID and/or Cert ID defined in Kunena configurationI've had my eye on these for a while.
Steve