TOPIC:

Hi all,

I've know this must have been answered a few times but I just want to make sure!

My '77 KZ650 stopped running recently. Sometimes I can get it crank over and idle, but barely. It will idle for a few moments then die. If i can get it to run for long enough, it's very rough. And not all cylinders are firing.

I am getting spark from each plug (B7ES), but it's yellow. So I tested the resistance on my coils. My Clymer manual says primary should be 4.0 ohms, and secondary 23K ohms.

Right Coil
Primary - 6.0 ohms
Secondary - 14.7K ohms

Left Coil
Primary - 5.8 ohms
Secondary - 14.5K ohms

I'm confused as to why my primary ohms are HIGHER than normal, but my secondary is LOWER??

I'd like to replace them with Dyna coils, but I'm planning on sticking with points for a while (don't have the $$$ for Dyna-S). I've heard conflicting answers on which Dyna coils to get.

Green (3 ohms) or Black (5 ohms)? Will one work with both points and Dyna-S?

Thanks in advance for any help. This community is awesome.

-Stephen

The Clymer manual is quoting early specs for the KZ650. Kawasaki later changed the specs even though the coils are the same. Using the revised specs your primary readings are a little high, but your secondary readings are well within the specs.

Before replacing coils I have 2 recommendations -

First - make sure your battery is not old or not holding a full charge. Unlike some later models, the 1977 KZ650 requires a fully charged battery to run properly because of its excited field charging system. Having owned my 1977 KZ650 for more than 37 years I can tell you that it will run like crap or not start at all if the battery is not up to snuff.

Second - Do a full tune-up on the bike. Points, condensors, check valve clearances, sync carbs (and make sure carbs are clean), etc. Often performing the simple, routine maintenance items solve what appear to be larger problems. Ed

krayneeum wrote: Hi all,

Right Coil
Primary - 6.0 ohms
Secondary - 14.7K ohms

Left Coil
Primary - 5.8 ohms
Secondary - 14.5K ohms

I'm confused as to why my primary ohms are HIGHER than normal,

Can your meter read low Ohms accurately? Connect the meter leads together and see what the 'zero" reading is then subtract that value from the test reading.

krayneeum wrote: Hi all,

I've know this must have been answered a few times but I just want to make sure!

My '77 KZ650 stopped running recently. Sometimes I can get it crank over and idle, but barely. It will idle for a few moments then die. If i can get it to run for long enough, it's very rough. And not all cylinders are firing.

Gas tank vent clear?

Inline fuel filters?

carbs cleaned?

I'd clean/replace your coil connection terminals, HT lead and caps before you junk the coils. A meter test on the bench might be misleading compared to what happens when fitted on the bike at 10,000 rpm and with heat and vibration .

I've had a coil meter as 'good' on the bench but breaks down intermittently when fitted, also coils that area bit out of spec according to the book but work just fine. Also it is very unusual to have two failing at exactly the same time

I think the early points and later IC ignitor ignitions had different coil primary resistances but look the same. Also I think there are some typos in the clymer manuals.

You sure this isn't a fuel supply problem? put the tap on' Prime' and loosen the drain screws at the bottom of the float bowls, rinse any sediment out out and see if they are all filing with fuel.

The pair of 1977 KZ650 coils I have measured just over 4 ohms. That's what I'd expect from any points-equipped KZ. If your measurements are accurate, then the resistance is high. Corrosion can increase the resistance, but 6 ohms does seem high even for that.

Two coils can measure the same, but one can still fail to produce adequate spark. A meter can confirem a bad coil, but cannot confirm a good coil. It has to be tested under high tension and fully hot. Of the two 650 coils I have, they measure about the same, but only one produces good spark.

Coils often do appear to fail at the same time. I had two go bad within 50 miles of each other. What happens is both coils develop small cracks over time. They can still work fine for years that way as long as they stay dry, but if the bike is then ridden in heavy rain, and the water works its way in, both coils can then fail suddenly. This usually happens when you are on a long trip, of course.

To answer the question, you can use the 3-ohm coils or the 5-ohm coils for both the points and Dyna S. The 3-ohm coils will shorten the life of points compared to 4-ohm or 5-ohm coils, but it will still work. If you might use the points for a long time, then the 5-ohm would be a better choice.

If it was my bike, I would try to get the Emgo 4-ohm coils. They are very similar to the stock coils, and they obviously work with the points, but will also work with the Dyna S. Most importantly, they cost less than half of the Dyna, if I recall. But they were out of stock at Z1 enterprises for awhile now.

loudhvx wrote:

If it was my bike, I would try to get the Emgo 4-ohm coils. They are very similar to the stock coils, and they obviously work with the points, but will also work with the Dyna S. Most importantly, they cost less than half of the Dyna, if I recall. But they were out of stock at Z1 enterprises for awhile now.

They are good coils, I am running one. Problem is they have been out of stock for months and I don't know what the hell happened to them.

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

650ed wrote: The Clymer manual is quoting early specs for the KZ650. Kawasaki later changed the specs even though the coils are the same. Using the revised specs your primary readings are a little high, but your secondary readings are well within the specs.

Before replacing coils I have 2 recommendations -

First - make sure your battery is not old or not holding a full charge. Unlike some later models, the 1977 KZ650 requires a fully charged battery to run properly because of its excited field charging system. Having owned my 1977 KZ650 for more than 37 years I can tell you that it will run like crap or not start at all if the battery is not up to snuff.

Second - Do a full tune-up on the bike. Points, condensors, check valve clearances, sync carbs (and make sure carbs are clean), etc. Often performing the simple, routine maintenance items solve what appear to be larger problems. Ed

Thanks for the reply Ed! Could you possibly send me the revised specs for the 77 coils?

I will go buy a charger tonight and try charging the battery. Hopefully this works!

The bike could definitely use a tune up, but I'm afraid I don't have the time to do this all before the season ends.

bountyhunter wrote:

krayneeum wrote: Hi all,

Right Coil
Primary - 6.0 ohms
Secondary - 14.7K ohms

Left Coil
Primary - 5.8 ohms
Secondary - 14.5K ohms

I'm confused as to why my primary ohms are HIGHER than normal,

Can your meter read low Ohms accurately? Connect the meter leads together and see what the 'zero" reading is then subtract that value from the test reading.

Good idea! Apparently my meter is off. It reads 1.3 ohms when I touch the leads together. With that said, my revised readings are:

Right Coil
Primary - 4.7 ohms
Secondary - 13.4K ohms

Left Coil
Primary - 4.5 ohms
Secondary - 13.2K ohms

Does that change anything as far as the condition of these coils go?

krayneeum wrote:

bountyhunter wrote:

krayneeum wrote: Hi all,

Right Coil
Primary - 6.0 ohms
Secondary - 14.7K ohms

Left Coil
Primary - 5.8 ohms
Secondary - 14.5K ohms

I'm confused as to why my primary ohms are HIGHER than normal,

Can your meter read low Ohms accurately? Connect the meter leads together and see what the 'zero" reading is then subtract that value from the test reading.

Good idea! Apparently my meter is off. It reads 1.3 ohms when I touch the leads together. With that said, my revised readings are:

Right Coil
Primary - 4.7 ohms
Secondary - 13.4K ohms

Left Coil
Primary - 4.5 ohms
Secondary - 13.2K ohms

Does that change anything as far as the condition of these coils go?

It won't change the secondary readings.

So your reading should then be:

Right Coil
Primary - 4.7 ohms
Secondary - 14.7K ohms

Left Coil
Primary - 4.5 ohms
Secondary - 14.5K ohms

That is much closer to what is expected for the primary side.
On the secodary side, are you including resistor caps in the readings? Maybe someone replaced them wih non-rsistor caps. That could explain the lower secondary readings.

If so, then the meter readings show no obvious fault, but that certainly does not mean they are definitely good. Like I said, I have two coils that measure out about the same, but one is not capable of producing the kind of spark the other is. Most likely there is a high-voltage leak in the secondary winding that only shows up with a few thousand volts on it.

Here is the tester I use to test them:
www.kzrider.com/forum/21-tools/561376-tr...l=component&type=raw

loudhvx wrote:

krayneeum wrote:

bountyhunter wrote:

krayneeum wrote: Hi all,

Right Coil
Primary - 6.0 ohms
Secondary - 14.7K ohms

Left Coil
Primary - 5.8 ohms
Secondary - 14.5K ohms

I'm confused as to why my primary ohms are HIGHER than normal,

Can your meter read low Ohms accurately? Connect the meter leads together and see what the 'zero" reading is then subtract that value from the test reading.

Good idea! Apparently my meter is off. It reads 1.3 ohms when I touch the leads together. With that said, my revised readings are:

Right Coil
Primary - 4.7 ohms
Secondary - 13.4K ohms

Left Coil
Primary - 4.5 ohms
Secondary - 13.2K ohms

Does that change anything as far as the condition of these coils go?

It won't change the secondary readings.

So your reading should then be:

Right Coil
Primary - 4.7 ohms
Secondary - 14.7K ohms

Left Coil
Primary - 4.5 ohms
Secondary - 14.5K ohms

That is much closer to what is expected for the primary side.
On the secodary side, are you including resistor caps in the readings? Maybe someone replaced them wih non-rsistor caps. That could explain the lower secondary readings.

If so, then the meter readings show no obvious fault, but that certainly does not mean they are definitely good. Like I said, I have two coils that measure out about the same, but one is not capable of producing the kind of spark the other is. Most likely there is a high-voltage leak in the secondary winding that only shows up with a few thousand volts on it.

Here is the tester I use to test them:
www.kzrider.com/forum/21-tools/561376-tr...l=component&type=raw

Oh wow, great information thanks!

I am NOT including the caps when i'm taking my readings, I should have mentioned that, sorry!!! Would that account for the low resistance?

Ed can confirm if the caps are resistor caps, and whether or not they should be included in measuring the secondary. I don't have a 650 manual.

The caps on the 650 coils look non-stock to me, so I don't have a resistance measurement for the secondary side of the 650 coils used in those photos and vid.

Resistor caps will add several K ohms to the secondary reading.