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Ignition Coil for DT400 CDI to Points Conversion

11 Jan 2020 13:22
pjandrew99
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Ignition Coil for DT400 CDI to Points Conversion #1
Hi Guys
In the process of converting my 1975 DT400 CDI to points/magneto from a 1975 DT250. I have no spark and looking at the coil next. Points and condenser are new and I think the source coil is fine. I'll dig into some other things down the road but want to be sure I use the proper ignition coil first.
I saw on a previous post that you could use the Emgo Universal Coil. It tested at 1.2 ohms on primary and 6.13K on the secondary. Since the spec is .61 primary and 6.0K secondary I assuming the Emgo is out of spec and will not work. I ordered a coil off ebay that was supposed to be for both the DT250 and DT400. It is a Motadin MIC102. The readings on that are .6 primary and 2.73K on the secondary. The stock F6T401 read .3 ohms primary and 5.65K ohms on the secondary. It is my understanding that the stock F6T401 will not work on a points system. So, before I throw any more money at coils, what is the proper coil to use when doing this conversion? Thanks!

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11 Jan 2020 13:52
MarkT
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Ignition Coil for DT400 CDI to Points Conversion #2
Emgo 24-71532 coil has always worked fine for me... I've also used stock CDI coil with points. Points magnetos don't seem to be too sensitive to coils... as long as a winding isn't shorted out or more commonly open... they spark.

Might be something else going on? What are you using for plug cap? Are you trying for spark with only the one black (or black/white) wire from stator connected directly to ignition coil? No other wires connected to that wire and none of the wires in the stator loom connected to ground or anything else?

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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11 Jan 2020 15:44
pjandrew99
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Ignition Coil for DT400 CDI to Points Conversion #3
Thanks Mark
Are you saying that any of those coils should work? If so I'll most likely put the Emgo back on.
I just purchased the OEM cap but haven't used it yet. Attached a picture of the wiring. That may be where the problem is.
Appreciate it!

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11 Jan 2020 16:00
RT325
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Ignition Coil for DT400 CDI to Points Conversion #4
Would have thought CDI coil should work. i swap all sorts of stuff around & they all work providing its got continuity & not an open circuit--which caught me out once.
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11 Jan 2020 16:30
MarkT
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Ignition Coil for DT400 CDI to Points Conversion #5
Might be... I can't see your wiring too well... normally orange from CDI box connector powers ignition coil on a CDI model. There is a black at CDI box connector but it's often a ground. Black/white at CDI box connector should be the kill wire that connects to ground with switch off and is open with switch in run position.

Best way to test if you're having problems is hook black from points in stator right to ignition coil with a jumper wire. Nothing else connected (except coil mount bolted to frame/ground)

You can use the stock harness like you're doing if you confirm (with ohmmeter or continuity tester) the black points wire is connecting to the wire in the harness that goes to the ignition coil and to the key/kill switch. Best to leave kill wire disconnected when testing.

As far as the coils, there are many recent cases of people buying new coils that are bad... the Emgo model I mentioned has always worked for me. And I have used the original CDI coil when converting to points with no issues at all. If ignition coil has "reasonable" continuity readings they seem to almost always work with points... as in not "open" or "shorted".

Also can try testing for spark without cap... just bare wire. Sometimes cap goes bad.

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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11 Jan 2020 16:34 12 Jan 2020 08:27 by MarkT.
MarkT
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Ignition Coil for DT400 CDI to Points Conversion #6

RT325 wrote: Would have thought CDI coil should work. i swap all sorts of stuff around & they all work providing its got continuity & not an open circuit--which caught me out once.


^^^ Yes, this has been my experience too... even if stock coil measures something reasonable... not necessarily even in spec... they work with points.

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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11 Jan 2020 16:56
Makotosun
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Ignition Coil for DT400 CDI to Points Conversion #7

MarkT wrote:

RT325 wrote: Would have thought CDI coil should work. i swap all sorts of stuff around & they all work providing its got continuity & not an open circuit--which caught me out once.


^^^ Yes, this has been my experience too... even if stock coil measures something reasonable... not necessarily even in spec... they work.


My recollection is the points and CDI coils are different, and at least in one direction they don’t interchange. Maybe DEET will weigh in and clarify.
The Emgo should work for both.

IF it isn't one thing, it's another.

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11 Jan 2020 23:51
Gr8uncleal
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Ignition Coil for DT400 CDI to Points Conversion #8
Partzilla lists the same coil for both.

Even if the points are new, still give them a clean (they can come with some sort of film on top). MarkT has posted recently on this.

For my DT360A conversion to points, I bought one of DEET's wiring harness 'converters'.
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12 Jan 2020 03:17
pjandrew99
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Ignition Coil for DT400 CDI to Points Conversion #9
Think I'll put the Emgo back on and test without the cap using the jumper wire Mark suggested. Eliminate the cap and plug variables. I may have wired this incorrectly or have a ground issue.

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12 Jan 2020 04:49
KennyV
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Ignition Coil for DT400 CDI to Points Conversion #10
If I remember correctly (I'm old, and it's been a while) my 250A and 400C both had the same coils.

71 Z50 Minitrail
72 RT2
74 250A
78 XT500E
06 F650GS Dakar
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