KZ650 - Question about Ignition/Coils - strange Problem

Dear Gents
Have strange termical problem on my full rebuildt KZ650 - 1978.
What happens (sorry for need to go a little further):
Before 2 weeks i have changed oil + filter. After i have done a short testride. Noted strange popping exhaust and after 10km the bike went suddenly out.No way to bring her alive again. After pulling the bike home i was able to start her again. However, start investigation: Intake manifolds damaged, changed to new one, complete carb supersonic cleaning, checked ignition (Accent German one) and detected, that one capacitor is bent/damaged (maybe during using wrench to crank over). Thought this is the problem and send that ignition for testing to manufacturer who has done a great job and repaired that thing for free. Put all together and thought i have found that problem.
Next testride: She runs very nice, no popping anymore. Good power. But after 10km again she went out suddenly. Same probelm, no possibility to start her again. Pulled home and there she starts again. 
Now i started again investigation and took a deeper look on coils (green Dyna) and voltage regulator (new Shindengen SH847AA for LiPo Battery).
Before i had the regulator placed above engine so this part received full heat. I moved the regulator on the front frame triangle (below frok tree). So now full in Airflow.
After i measured resistance of the coils. 
High voltage output have strange high resistance of 19.98Ohm. Coils heated up with airgun at 120 degree resistanvce changed to 21 ohm. Even noticed that HV Connector on Cylinder 2 is black/burned. See picture. So for me this coils are both damaged. 

Now my questions to you:

• Have ordered new coils form Dynatek. Now the black one with 5 Ohm because they mention that black is better for street use. Am i right?
  • Also orderes new HV Cables from Dyna - with cooper core (not graphite which i had used before). Better?
    
• Setup of Coils: I have seen that sometimes a additional resistor is mentioned between Coils and Ignition. I do not have something like that. Important?
  • Additonal information: Complete wires are new. I use Motogadget Blue Unit. 
    
• What do you think why HV Cable 2 is burned and what could be the reason why coils are damaged?
• Any ideas left what i should check additional or simply put in new coils and test?

Many thanks for your help in advance!

Cheers Chris
 

Dyna coils are a very tight fit to the coil mount plate, so much so that I have seen cracked coil cases which then break down with heat. 
Remedy is to make langer mounts so that you can clearly see space between the coil body and the mount plate. 
The longer mounts need to be made of metal so that they continue to dissipate coil core heat to the frame. 

wrote:

Dear Gents
Have strange termical problem on my full rebuildt KZ650 - 1978.

Now my questions to you:

• Have ordered new coils form Dynatek. Now the black one with 5 Ohm because they mention that black is better for street use. Am i right?
  • Also orderes new HV Cables from Dyna - with cooper core (not graphite which i had used before). Better? - 5 Ohm coils should be fine as long as you have full battery voltage supplying them - copper core leads are better
    
• Setup of Coils: I have seen that sometimes a additional resistor is mentioned between Coils and Ignition. I do not have something like that. Important?
  • Additonal information: Complete wires are new. I use Motogadget Blue Unit. - The additional resistor (ballast resistor) is only used on some models and would be used with 2 Ohm coils
    
• What do you think why HV Cable 2 is burned and what could be the reason why coils are damaged? - The burning will be a result of a loose connection causing sparking between the coil and the lead - from what I have read in other posts the newer Dyna coils don't seem to very good quality and failure is common (also leaving the ignition on without the engine running will quickly burn out coils)
• Any ideas left what i should check additional or simply put in new coils and test? Apart from checking supply voltage to the coils I would wait for your new parts and see what happens.

Many thanks for your help in advance!

Cheers Chris


 

wrote:

Dyna coils are a very tight fit to the coil mount plate, so much so that I have seen cracked coil cases which then break down with heat. 
Remedy is to make langer mounts so that you can clearly see space between the coil body and the mount plate. 
The longer mounts need to be made of metal so that they continue to dissipate coil core heat to the frame. 

Thanks Warren!
Have made alloy spacers, you can see them on the picture with the regulator. So coils was mounted nice without bending or touch to mounting plate.

It sounds also like a battery charging issue.

Start the bike and check the voltage at the battery post(metal part of battery) . Raise the rpm to 2000, turn on your high beam on your headlight and check voltage again.

This is of interest to me because I'm currently restoring a 78 KZ650.  My plan was to use a Dyna pickup with the original coils.  (I have two sets.)

I'm wondering why you didn't use the Dyna pickup?  

The green Dyna coils should have worked fine, as they are essentially the same resistance as originals.

The ballast resistor you mentioned is used on some engines, like the KZ1000, but with the brown (2 ohm) Dyna coils.  This gives them a total of 4 ohms. (nominal)  This was the factory setup on my 1980 KZ1000, along with an exciter.  I removed the entire ignition system and replaced it with green coils and a Dyna S pickup.

wrote:

It sounds also like a battery charging issue.

Start the bike and check the voltage at the battery post(metal part of battery) . Raise the rpm to 2000, turn on your high beam on your headlight and check voltage again.

Hi!
Thanks for that suggestion, but Voltag is rock stable in all situations - i see that always displayed on my Tacho and it is always (above 1500rpm) nailed at 14.2 which is perfect for my Lithium Battery Setup. Idle voltage is even always 13.3V. 
The coils receive more or less same voltage.
Cheers!

wrote:

This is of interest to me because I'm currently restoring a 78 KZ650.  My plan was to use a Dyna pickup with the original coils.  (I have two sets.)

I'm wondering why you didn't use the Dyna pickup?  

The green Dyna coils should have worked fine, as they are essentially the same resistance as originals.

The ballast resistor you mentioned is used on some engines, like the KZ1000, but with the brown (2 ohm) Dyna coils.  This gives them a total of 4 ohms. (nominal)  This was the factory setup on my 1980 KZ1000, along with an exciter.  I removed the entire ignition system and replaced it with green coils and a Dyna S pickup.

Hi!
Regarding the ignition i prefered Handmade in Germany
This ignition is quoted from a lot of people here in europe very well. 

But question is: Will i have disadvantages using 5Ohm black coils?

Are you running the pickup to an exciter or directly to the coils?

No, 5 Ohm coils would be okay but your R/R cooling fins are unfavorably placed and exposed to the heat of the cyl. head.

wrote:

Are you running the pickup to an exciter or directly to the coils?

The Accent ignition is an improved Dyna like ignition made in Germany.

z-fever.de/shop/en/product_info.php?info...uendanlage-z650.html

 

wrote:

No, 5 Ohm coils would be okay but your R/R cooling fins are unfavorably placed and exposed to the heat of the cyl. head.

Thanks mate, still have changed the mounting position to the front of the bike. Now full air cooled