No spark fault finding
#11
Another thing worth checking is the connector block from the alternator to the wiring harness situated beneath the LH tank...if you have any corrosion in the spade connectors, that could be your problem.
Dave.

I had that problem a few years ago, since then I checked the other bikes, opened up the blocks, stuffed them with vaseline, popped them back together and no issues since.
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#12
Just an update and also to set this out in a way that can be a useful reference for anybody else.

No spark fault finding:

1. Check ignition coils. Primary 0-1 ohm and secondary 10-17 K ohms
2. Check that the CDI is getting power. It is an AC CDI and is powered by the source coil in the stator. Black/Red and Red/Black. You can take an AC current reading across these wires. No specs in the manual but I measured around 50VAC. Resistance should be 230 to 355 ohms.
3. Check pick up coil. Green and orange wires. 175-265 ohms. This sends a signal to the CDI that lets it know the position of the crank.
4. Check side stand switch by checking continuity between earth and light brown fabric insulated wire at the CDI. When the stand is up this wire should be earthed.

The ignition switch and kill switch also send an earth signal to the CDI when they are in the run position, but if there is a fault here the starter won't turn. Same with the neutral switch.

Also take your readings, wherever possible, at the connectors for the CDI as this will also show up bad connections in the wiring harness.
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#13
What did you find on your bike?

Is it running now?
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#14
Well after checking everything I found no faults. But still no spark. So I ran an extra earth wire to the frame and immediately it fired up. I've been using it the last few days and although it does start, it doesn't fire as quickly as it should. So I think the next step is to remove the coils and make sure all the earthing points are good and clean. And possibly run an earth wire directly to the coils.

(28-01-2021, 02:22 PM)dave#22 Wrote: Another thing worth checking is the connector block from the alternator to the wiring harness situated beneath the LH tank...if you have any corrosion in the spade connectors, that could be your problem.
Dave.

I had that problem a few years ago, since then I checked the other bikes, opened up the blocks, stuffed them with vaseline, popped them back together and no issues since.


Thanks Dave. I did my checks for the alternator initially at the CDI connectors, so that I could be sure that the signal and power was actually reaching the CDI. If you just check at the connector closer to the stator, it doesn't rule out the possibility of an issue in the wiring from there to the stator. But I did also open and check those connections and took more readings there just to make sure there was no difference in the values.
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#15
So the plot thickens. The extra earth wire only provided a temporary fix, or was just coincidental. It seems the spark issue is intermittent. So I'm looking at the source coil again and the wiring to the CDI. The source coil resistance is in spec when I check it but that doesn't guarantee it's always like that I suppose. Does anyone know what the output is supposed to be? I'm getting 41VAC while cranking and about 59VAC max while running. These are the black/red and red/black wires running to the CDI.
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#16
Don’t know if this will help but....

On my Honda Transalp and my Africa Twin (both from 89 and 90) CDI box failures are a common occurrence. The physical boxes differ in size and type from the Suzuki and I know the Suzuki part does not seem to fail

However, when the Honda CDI modules fail they rarely do so completely. The failure is almost always intermittent. Over the years it has been traced back to the physical solder joints where the large multi-wire plugs are soldered onto the green circuit board of the CDI unit.

Micro cracks appear at these solder joints after roughly 25 to 40 thousand miles. It’s unknown whether this is a result of vibration or a function of the owner physically removing the wiring from the boxes to access other parts of the bike for repair of maintenance.

The reason I bring this up is due to the intermittent type of failure. The cracks in the solder joints are so small as to usually require magnification to see. In the real world, the affect on running seems totally random but the advantage is that the Honda is a twin cylinder bike so the bike will run but just drop one cylinder. Since one CDI also runs the tachometer, this is commonly used to trace the faulty box but not possible on a single.

If you can find someone with a spare CDI, I’d try exchanging it.
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#17
Thanks Ray. I had got to the point where I was strongly beginning to suspect the CDI. When I started researching CDI failures on the net, the Hondas definitely dominated the discussion, and particularly the Transalps, Africa Twins and the XR650's. But similar intermittent symptoms.

Unfortunately the bikes are very rare here so no one I could swop CDI's with, and I wanted to be 100% sure before buying another CDI. So I started looking again at the source coil. It seems that CDI failures on the DR are rare but source coil failures are not unknown. The resistance of my source coil was 100% within spec but I did sometimes get varying results with the voltage outputs so I sent it in to be rewound. The guy who did it sent me pics and said he was surprised it worked at all, such was the condition.

After I reinstalled it, the bike fired up first time and had a nice healthy spark, so the source coil had definitely not been working properly, despite the fact that the resistance measured within spec.

So problem finally solved I thought, but the next day the bike was dead. No spark. Long story short, the problem is somewhere in the kill switch, or kill switch wiring. Once that wire was disconnected from the CDI the bike has been working perfectly.
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