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Makotosun

[Help] with my '73 DT3 250, having ignition issues

  • MarkT
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I'm not sure reversing the wire connections would work...  the actual direction of the winding makes a difference with the magic...  but I'm just guessing about it even causing an issue.

All I remember from college vaguely is "right hand rule" and "left hand rule" where you use your curved fingers to point in the direction the wire is wrapped around the core and your thumb then points in the direction of electron flow or something like that.

Another thing that definitely could cause an issue with the "pulse timing" is where the stator coil is mounted on the stator plate.  Did you bolt the ignition source coil back in the exact same position on the stator that it was removed from?
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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29 Jan 2023 18:04 #61

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Wouldn’t the movement of the flywheel and the direction of the magnet determine the start and end of a coil?
Sneezles61
29 Jan 2023 19:34 #62

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  • MarkT
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A few years ago I spoke to one of my buddies who is a genuine electrical engineer...  He told me that these fixed output magneto/alternator systems are very simple and reliable from a mechanical and maintenance perspective  ...  but at the same time, the engineering design is insanely complex in terms of the magnetic flux and how all the coils relate to each other as the magnets spin and the electricity flows.  He didn't think there were more than a dozen people in the world today that truly understood how to design a magneto ignition with lighting coils that "balance" the output against the load and don't require a voltage regulator.

He said more modern systems are simply an fixed output alternator designed to put out plenty of power to run an electronic ignition and lights...  then electronics are used to store and/or regulate any excess output...  more like a car alternator than the "magic" used before semiconductors became cheap and available. 

The fact that these early mags aren't loaded down with electronic components is what makes them reliable as a rock...  you might get lucky changing the way it was built (even something like rewinding coils for 12v light output can impact the points magneto ignition system) or you might end up with a strange problem. 
 
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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29 Jan 2023 20:16 #63

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Replied by AirborneSilva on topic [Help] with my '73 DT3 250, having ignition issues

Like Mark T said your timing should be at 3.2 BTDC not 2.8.
2023 Tenere T7
1976 DT400C
1975 DT400
1981 DT175H
1972 DT2 250
1980 GT80
1972 JT2
30 Jan 2023 02:01 #64

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Pretty sure someone else like RT325 mentioned the correct timing number... 

I've just been rambling on about how simple these systems seem but are sensitive to "design changes".  Paying attention to all the little details is important once you start "rebuilding" a stator.  Lots of "hidden engineering" in these ignition/charging/lighting systems.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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30 Jan 2023 04:43 #65

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  • 19stuberd
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Hello everybody!
Bad news! Reversed the wires, now it won't spark in either direction. AWESOME! I'm sure you're all pretty damn tired of this thread and I don't blame you at this point. I am trying to stay upbeat, here's ,my plan:
+Get the good flywheel puller. Gonna have to do this a lot, might as well do it right.
+Revert the wires to original positions, put it on, see if it behaves as expected. If not, maybe I messed something up when I did my soldering, there was some sketchy wires in there.
+If the reverted wires behave as expected, I will use the spare source coil core and wind a new coil in reverse. Put it on, check what happens.
+If still no luck, I'll take it all back to the oscilloscope / hyper-precise multimeter and see what's going on.

*also, I will take a look at the oscilloscope readings from this most recent stage, even though I don't think anything new is in there.

Any input is GREATLY appreciated. I'm pretty down in the dumps. Ask your neighbor for their advice, say a prayer, ask your dog, whatever you can. Thanks again guys.
30 Jan 2023 13:20 #66

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Additional, potentially significant update- I have just reviewed a video that I took of the original coil and it does indeed appear as though I have wound it backwards, i.e. windings go around the opposite direction that they were supposed to. My fingers are crossed that we're onto something with this.

Also checked the manual again and you guys are right, it's supposed to be 3.2mm. I think I was looking at the RT3 by accident. This might be convenient though because there's a suspicious wire connection that routes under the points that I wanted to investigate but I didn't want to mess with the points timing, but this gives me an excuse to do so. We'll see what happens after I revert the wiring to its original state.
30 Jan 2023 13:37 #67

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Replied by AirborneSilva on topic [Help] with my '73 DT3 250, having ignition issues

Unless you're actually enjoying this I'd just ship it off to DEET and let him rebuild your stator for you but then again I wouldn't have attempted it in the first place since I know little to nothing about auto/motorcycle electrics...
2023 Tenere T7
1976 DT400C
1975 DT400
1981 DT175H
1972 DT2 250
1980 GT80
1972 JT2
30 Jan 2023 13:38 #68

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  • 19stuberd
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Another update- Just reverted the wiring and put it back on, it's doing the same thing it was before and only igniting in reverse. Next up is to make a new coil in the right direction. Wish me luck!

Also I would certainly consider sending it in to be redone but I do actually enjoy the electronics bit I would say, I think it's all within my skill range (erm... if you ignore the backwards coil lol) for the most part.
30 Jan 2023 14:20 #69

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Fingers crossed!
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
30 Jan 2023 14:46 #70

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