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Only One Coil Sparking


Brian_GS

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Hi,

I have a Suzuki GS650GT and having problems starting. Only one of the coils are sparking. When I switch the wires over from the working coil (BLACK/YELLOW & ORANGE/WHITE)  to the non working coil (WHITE & ORANGE/WHITE) then that coil is working and the other one is not. So both coils are fine. I have gone through the whole wiring loom to check wiring and everything seems ok. I have done all the OHM tests on both coils and they seem to be ok.

My question is. Is it the the CDi (Ignitor) or the Signal Generator that is dead. if any....

You can view the GS650GT Wiring Diagram (in color) below.

Please.. Any help on how to diagnose further will be appreciated. Anyone that has maybe gone through  the same issue...

Thanks in advance

gs-650-wiring.jpg

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Brian: welcome to OSS.

I see this is your first post.  You may have a hard time getting an answer to your problem without first introducing yourself.  Members here don't like taking the time to solve your problem, and then never here from you again.  Go over to the "general chat" section and start an introduction thread; tell everyone a little about yourself as it relates to Suzuki motorcycles.  It doesn't matter if you have been riding and wrenching for fifty years or if this is your first bike.  You will find OSS to be a treasure of information and members glad to help. 

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3 hours ago, BigT said:

You can't tell whether it's the signal generator or the ignitor without testing. The signal generator is easy, the ignitor is tricky

So, work your way from the coils back to the signal generator, or vice versa

Yes and No LOL! Depends if the pick-ups have a single or dual pick-up arrangement. If dual, the wires can be swapped over like the coils, before the 'CDI' - the problem should swap coils . . . . . . . subject to the wiring checking out ok! But pick-ups rarely are a problem . . . . . 'CDIs' on the other hand - based on age - quite often are suspect / fail and need replacement!

Edited by Gixer1460
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I've found on my 82 gsx , the female pins in the connector blocks had increased diameter, so the actual joint was bad and much lower , if any, current got through .   It's where they are bouncing around abit and those forces kinda bend them . 

  Sounds crazy right lol. I was stumped, running on two, intermittent and weak spark,   tested for volts at the coil LT and those wires in the connector and back at the cdi box.  I first thought the cdi was not ^switching^ properly,  then tested the volts the other side of the connector plug randomly and figured out it was the connector .  Even then it took time to see the male and female pins didn't fit together tight ,it all looked fine ! 

There's an ignitor test bit in the suzuki service manual quite interesting,  u can see the spark at different times , can't totally remember .  Might help .  Carry on ..

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17 hours ago, Blubber said:

HAve you checked the wires behind the right hand side cover al the way towards the igniter? Wires can break or get dislodged in their connection. 

 

Hey Blubber, Yes, I checked the complete wiring harness now. All wires seems to be 100%. I have gone through from below the tank all the way back to the back flickers and from the signal generator all the back up to the CDi. All wires are 100's. I also measured the OHMs of the  signal generator (I'm getting 350 ohm) According to manual that seems to be ok. I just don't know how to test the CDI, if even possible. That is the only thing left to my understanding..

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15 hours ago, Gixer1460 said:

Yes and No LOL! Depends if the pick-ups have a single or dual pick-up arrangement. If dual, the wires can be swapped over like the coils, before the 'CDI' - the problem should swap coils . . . . . . . subject to the wiring checking out ok! But pick-ups rarely are a problem . . . . . 'CDIs' on the other hand - based on age - quite often are suspect / fail and need replacement!

I managed to test the signal generator (Blue & Green) Im getting 350 ohm which according to manual seems to be fine. Do you think the only logical explanation left is the CDI. ?

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Check out all wiring and connections from the signal generator to the CDI and from the CDI to the coils, earth etc. Remove the loom tape to do this properly as there may be joins in there. Check the actual connections on the CDI, as these can corrode and work loose, especially on CDIs into which the connector blocks plug in directly. If it still doesn't work, then your CDI is probably buggered.

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Since there is only one signal generator (pick-up coil) it's very unlikely culprit. Fault there would affect on both coils.

Have you already checked 12V supply to the coils? Just measuring it with a multimeter may not be enough if there is a marginal connection somewhere. It may give good voltage readings but still can't supply enough current. To be sure you can test it with a light bulb to simulate load of the coil.

But otherwise it sounds that the igniter unit starts to be the most likely fault.

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So you have twelve volts at the low tension on both coil ? If not how far back till you find it ? At the coil connector block ? At the cdi ? The cdi switches one coil to the other .  Get a pdf of the suzuki factory service manual it session how to test the cdi (in a limited fashion) with a voltmeter .  How is the contact between the pins on the connector blocks .  

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swap the leads over between the coils, if the same coil refuses to spark, its the coil, if the failure to spark moves to the other coil its the pickups. if its the gs650 motor then it should be twin pickups with mechanical adv ret, they only went to single pickup when they moved to the efe 16v motors with electronic advance and retard didnt they? certainly the 650 gs motors in my garage have the same ignition setup as all the gs 8v range and the early 16v kat/et gsx motors.

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Howsit Everyone,

I managed to get a secondhand CDI/Signal Generator and it fixed my problem. The Pickups was fine, measured 350 OHM between green and blue so I sorta thought it could only be CDI. Thank you everyone for your input. Really appreciate it. Now it is taping the whole wiring loom again, put everything back and go for a cruise :)

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