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TOPIC: DT360/400 CDI Box replacement in Development!

DT360/400 CDI Box replacement in Development! 07 Aug 2017 20:33 #1

  • Makotosun
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I was recently contacted to see if I know anyone with a good, working DT400 ignition on a bike to do some R&D testing of a new CDI box being developed for the Mitsubishi CDI used on 74 DT360, 75-76 DT400 and MX400 as well as a couple of other bikes.

I am happy to announce that I received a test unit this past weekend, and was able to plug it into (truly plug and play!) my Suntank bike which runs that ignition. By every test I could run, including a timing advance comparison, the unit appears to be a functional clone of the original. If anything, my bike idled just a bit smoother with the aftermarket box.

I don't have an exact timeline for these to go into production, or a cost, so will wait for more info from the developer. I think it is safe to say these will likely be $200 or less when available.

This is a really exciting development in the ongoing saga of keeping these old girls running. If only we could find someone to create/repop the pulsar coils - maybe make them a bit more reliable :whistle: we would have something!

More news when I have it.

Since we all like to see pictures and videos, here is a short clip of my bike running with the test unit installed.

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DT360/400 CDI Box replacement in Development! 07 Aug 2017 20:36 #2

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Great stuff!! :OnFire
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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

DT360/400 CDI Box replacement in Development! 07 Aug 2017 20:47 #3

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I will be running this test box as much as I can find time to ride this next week to assure a level of dependability and will post more info as I have it. I am familiar with this manufacturer and can vouch for their credibility.

There are a few small finish details I am suggesting to them to make it more exact to factory, but these even include the proper 3 prong male/female combo plugs as used on the originals. Nice touch. I am guessing the instruction manual will be limited to remove and unplug the old, replace and plug in the new, and then go riding!
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DT360/400 CDI Box replacement in Development! 08 Aug 2017 15:27 #4

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Your post had me thinking the other day about CDI boxes. What makes a CDI box differ through the various models? Like why couldn't you use a DT400 CDI box on a DT175?

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DT360/400 CDI Box replacement in Development! 08 Aug 2017 16:18 #5

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Good question. Thye are designed for different trigger/pulsar coils, but otherwise, maybe someone can chime in on a more technical basis!

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DT360/400 CDI Box replacement in Development! 08 Aug 2017 17:40 #6

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I wish they had this setup for the old points style bikes. I would dump my points in a heart beat

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DT360/400 CDI Box replacement in Development! 08 Aug 2017 18:10 #7

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There actually may be such an animal in prototyping. He fellow I am working with had something similar.

For a complete replacement of points with CDI, Powerdynamo has you covered.
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DT360/400 CDI Box replacement in Development! 08 Aug 2017 18:13 #8

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Does it have lighting coil also. This is for a rt2

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DT360/400 CDI Box replacement in Development! 08 Aug 2017 18:21 #9

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Makotosun wrote: Good question. Thye are designed for different trigger/pulsar coils, but otherwise, maybe someone can chime in on a more technical basis!


Even in some of the early CDI's there are some rudimentary advance/retard curves built into the box... That's one difference that could make a box built for a larger engine not be the best for a smaller engine.

Beyond that, when I was working with Powerdynamo on the Yamaha 175 ignition kits, I learned, just as Mako said, the stator coils and even the magnetic field strength of the flywheel changes the design of the CDI box.

For example, the Powerdynamo Yamaha Enduro 125/175 kits use identical stator coils. Same pick up coil, same source coils, same lighting coils. Identical. You can choose a very light flywheel which is smaller and has less magnetic force than the larger, heavier flywheel options. One result is you end up with less wattage available to run the lights with the light flywheel.

What I learned is that the CDI box is also different for the different size flywheels Specifically the size rating of the capacitor (the "c" in CDI). The way it was explained to me is that the lower magnetic force of the small flywheel doesn't charge up the larger capacitor used with the heavier flywheels as well as it should so the spark suffers a bit. Conversely, if you would use the CDI box designed for the small flywheel with the large flywheel, the smaller capacitor ends up getting overcharged and could overheat and fail.
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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

DT360/400 CDI Box replacement in Development! 03 Sep 2017 08:15 #10

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UPDATE:

So the initial box worked really well - easier to start, smooth running, but the developer was concerned about high revs and how it would do. After some additional tests, I have now received prototype #2 which will be given some tests today. We seem to be vectoring in on a solution.

More soon.
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