Ignition coil resistance - KTM Duke 390 Forum
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post #1 of 11 Old 12-03-2019, 06:09 PM Thread Starter
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Ignition coil resistance

OK gents what resistance should we get from a good ignition coil with the meter set at 200? I'm getting only 0.4
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post #2 of 11 Old 12-04-2019, 09:10 AM
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The resistance of the primary side will be around 1-2 Ohms and the secondary side should measure somewhere between 6-10,000 Ohms
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post #3 of 11 Old 12-04-2019, 09:55 AM Thread Starter
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Thanks for that I have only check the primary side and it's only showing 0.4-0.5 at best so could be a fault then. I'll check the secondary to be sure
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post #4 of 11 Old 12-04-2019, 11:26 AM
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1 to 2 ohms equates to 12 to 6 amps

0.4 ohms will take 30 amps so check whatever is supplying it, could be damaged.
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post #5 of 11 Old 12-08-2019, 04:28 PM Thread Starter
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Could someone check there coil to see what the readings are before I order a replacement.

Mine is 0.4 primark meter set at 200
Secondary is 5.4 meter set at 20k
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post #6 of 11 Old 12-08-2019, 06:12 PM
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Quote:
Originally Posted by Graham bothwell View Post
Could someone check there coil to see what the readings are before I order a replacement.

Mine is 0.4 primark meter set at 200
Secondary is 5.4 meter set at 20k
Is that 0.4 of the full meter deflection? Or 0.4 ohms?
Same with the other reading 5.4 what?
Are you using an analogue meter? If so you're reading off the wrong scale maybe.
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post #7 of 11 Old 12-09-2019, 05:34 PM Thread Starter
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It's a digital meter and I'm taking omhs resistant off the primary and secondary
Primary off the two connectors to the coil. Secondary off one of the connectors and to the plug cap
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post #8 of 11 Old 12-09-2019, 06:02 PM
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I'll drag a scope and dvom to the house as soon as work is done here. I've got a 2019, but yours and mine 'should be' the same on this key point.


This isn't something I have yet tested on the Duke, so I'm sure I'll get 'something' out of it, right? I do tend to agree with what Lightning said, however, because [more than 1 but less than 2] is usually the norm on the primary of a single pole coil.


So if you're wondering why I would even bother taking a scope along for the ride(?). It's because I wanna confirm whether this is dwell-based coil saturation or if this is a capacitive discharge type ignition -- nobody's ever clued me in on that and it could have a bearing on coil primary winding resistance.


I'll post back as soon as I have the facts about all that.
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post #9 of 11 Old 12-09-2019, 07:32 PM
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Hold the phone Graham...


It really is a 0.50 ohm primary and a 5600 ohm secondary.


Gimme a few minutes, I'll post back the rest.


But to this point... I used a SnapOn MT586A DVOM. and, Yes, I zeroed the meter, by setting the 'Relative' (elimination of my meter's leads resistance), b4 I tested for the 0.50 ohm primary. Then I tested it again because I was a little shocked (not literally).


BRB. gonna hit the scope.
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post #10 of 11 Old 12-09-2019, 08:29 PM
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Ok, I've attached the pic for the ignition pattern. The scale is 10V per vertical division and 500us per horizontal; the scope is a Sun LS2000 (23Mhz). You can see it's a conventional dwell-saturated waveform... but of cors, the wiring diagram kinda gave that away at 1st glance.



Your coil is fed battery voltage from fuse 4 (15A), according to the 2016 Duke 390 diagram, on the or-wh wire. That's the same as a 2015; you have a 2015, right? But I didn't have a 2015 manual, so we're improvising over here.


I'm gonna go put my bike back together. I'll keep an eye on the thread in case there's anything else I can do to [help?].
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