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Faulty CDI ?? Dr 350s '91

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Hi all. Please see this thread: https://thumpertalk.com/forum/showthread.php?t=1006443 for some background info on the bike and previous problems..

What I'm wondering is how accurate the ohm-test of the CDI is..? I've been testing it according to the original Suzuki manual, and my readings are WAY off! Much too high resistance with every two wires I'm testing. Have anyone here tested their cdi (or is willing to do so to compare)? I don't feel like spending all that money on a new unit before I am completely certain of what the problem is.

Naturally, I have spark issues with the bike. And the ignition coil checks out per the manual.

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Ohm testing a CDI is problematic. The resistance between wires is not linear due to all the semiconductor guts. This means different meters with different current sources on Ohms setting will produce different results. Your CDI might well be hosed, but unless you have the Suzuki approved 'pocket tester', your mileage may vary.

Do you get any spark at all? The stator is more often the real problem. You can usually ohm that out reliably.

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Ohm testing a CDI is problematic. The resistance between wires is not linear due to all the semiconductor guts. This means different meters with different current sources on Ohms setting will produce different results. Your CDI might well be hosed, but unless you have the Suzuki approved 'pocket tester', your mileage may vary.

Do you get any spark at all? The stator is more often the real problem. You can usually ohm that out reliably.

I do not own the Suzuki "approved" tester, but what I was curious of, is that the ohm-resistance differs extremely from what the Suzuki manual says. And between the white and the some of the other wires, the resistance just keeps on rising slowly, and seems to "never" stop.. Was kinda hoping I had found the problem.

I just replaced the stator on my other bike (old gs650g katana) and was hoping that wasn't the problem on the DR. I do have spark, but just occasionally visible, but I feel the electricity in my hand with every kick. When everything put together and kicking to start the bike, it's like it only wants to fire on 1 out of 4 kicks..

What would be the easiest way to ohm the stator on the DR?

Edit: Nevermind, I just tested it, and it checks out (still not with the Suzuki tester, but within specs of what the manual says.)

Edited by Smyg

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I do not own the Suzuki "approved" tester, but what I was curious of, is that the ohm-resistance differs extremely from what the Suzuki manual says. And between the white and the some of the other wires, the resistance just keeps on rising slowly, and seems to "never" stop.. Was kinda hoping I had found the problem.

That's probably a capacitor charging up. It might be normal, it's hard to say.

I do have spark, but just occasionally visible, but I feel the electricity in my hand with every kick. When everything put together and kicking to start the bike, it's like it only wants to fire on 1 out of 4 kicks..

That's encouraging. Have you checked the spark plug wire connection?? Those are known to go bad over time. Unscrew the spark plug boot from the wire. You should see some copper in there, if not, cut off a small amount (no more than a mm or so) and screw it back on. If that doesn't work, the spark plug boot might be bad. You can get a replacement at any motorcycle shop for low cost.

You might try to measure the source coil voltage. Set your meter on AC and connect it to the source coil (red and white wires I think). Hold the decomp lever and kick. If you get 100 V or more, it's probably OK.

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I've already replaced the ignition coil, plug wire and cap earlier this summer. Spark plug also. I've now ordered an aftermarked cdi from Belgium through ebay. Nice price. Hoping for the best.

Had to order a new regulator for my other bike also. What is it with these old Suzukis and electrical problems??? I've previously owned an older GR650 that I had to replace regulator on also. Am I cursed?

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What is it with these old Suzukis and electrical problems??? I've previously owned an older GR650 that I had to replace regulator on also. Am I cursed?

I doubt it. A lot of people tend to beat on these bikes for one reason or another. The previous owner of my bike did all kinds of crazy things that caused more harm than good. Still, it has held up well for a 20 year old bike. Of course, I always keep it in the garage and perform all scheduled maintenance on time.

If it turns out that your CDI is bad, I'll buy it for a nominal fee. I can use the connectors for my ignition project. Let me know...

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So I have finally replaced my original cdi with an aftermarked one from Belgium. And - voila! I'd never thought this day would come! By some miracle, the bike runs. Doesn't stop at lights or anything. I feel so much better now, after struggeling with this bike for half a year now.. So both ignition/spark AND carburrator issues, which was hard to find on top of it all. Whew..

The only thing I now doesn't understand, is why the neutral indicator light and rpm-meter doesn't work with the new cdi.. ?

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The only thing I now doesn't understand, is why the neutral indicator light and rpm-meter doesn't work with the new cdi.. ?

I know the tach requires a signal from the CDI. It's possible the aftermarket CDI doesn't supply the correct signal. The neutral might be similar.

PM me if you want to sell your old CDI.

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Aha. Makes sense. Makes me also not care that much that it's not working. 👍

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