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TOPIC: No Spark after carb rebuild DT400

No Spark after carb rebuild DT400 31 Mar 2019 12:14 #41

  • MarkT
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yamahahaha wrote: Not to hijack your thread but does the donor DT250 have to have the EXACT setup that came with it ( Stator / Flywheel /Coil ) in order to work on the DT400 ???


You need a points stator and points flywheel set from the DT250. Ignition coil might have different specs but CDI coil seems to work fine with points in my experience. Yamaha points magneto design is sometimes called a "mechanical CDI".
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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

No Spark after carb rebuild DT400 14 Apr 2019 20:11 #42

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Update:

I bought a timing light and cranked over the bike. I used a drill connected to the flywheel with the outer of my flywheel puller.

I found that the timing mark was showing the pulsar blade need to rotate about a 1/8th turn counterclockwise to match with the timing mark on the flywheel.

This was much more than the adjustments on the pulsar or the stator backing plate would allow. I drilled a few new holes in the plate to allow for the rotation needed.

After aligning the plate I cranked it over again. This time I could not get a spark. Hmmm...

A few days later a friend of mine called and said he had a Rex's Shop shop stator kit for a 74 DT250 that I could try if I wanted.

My new question is:

Would a Rex's Shop shop stator kit for a 74 DT250 work?

I'm near the end of my patience with this bike and am tempted to go a different direction if I can't get it going soon.

Thanks again for everyone's help on this one.

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No Spark after carb rebuild DT400 14 Apr 2019 20:52 #43

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If he has everything needed to get spark on a DT250, it will fit your 400.

(DT250 had points, so if it Rex stator has points you'd need the flywheel to go with it.)

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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

No Spark after carb rebuild DT400 15 Apr 2019 08:32 #44

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Thanks Mark!

I hooked up the Rex's Shop shop stator kit last night and I have spark! It also doesn't kick back now. It doesn't want to fire over though, so I'm not over the bridge quite yet.

I'm thinking of starting by pulling apart the carb and installing the jetting that was in it previously instead of the jets that came with the rebuild kit. Is that a good place to start? What else am I missing here?

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No Spark after carb rebuild DT400 15 Apr 2019 10:38 #45

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Rebuild kit jets are almost always junk. Go back to original

How did you set the timing on the Rex kit? Pictures of what it looks like?

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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

No Spark after carb rebuild DT400 15 Apr 2019 11:34 #46

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Ok I'll hopefully get time to reinstall all the original jets tonight.

The kit has no adjustment for timing and touts that it is bolt on and go.

I'll take photos tonight. I have also reached out to Rex's to verify fitment on a DT400 vs the DT250 the kit was originally for.

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No Spark after carb rebuild DT400 16 Apr 2019 18:21 #47

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how did the rwx thing work out?????

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No Spark after carb rebuild DT400 17 Apr 2019 12:05 #48

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No word back from Rex's yet. hoping to hear back soon

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No Spark after carb rebuild DT400 27 May 2019 08:37 #49

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Update: I got it running!!

So after reaching out to Rex’s Speed shop about the DT 250 12v Stator Kit my friend gave me, they wrote back and said that it would not work. The stator is different and the CDI unit is different.

They offered to exchange it if I paid for shipping both ways to England.

So I sent it back and about a month later I got the DT 400 stator kit back.

I installed it and kicked it over a few times. After about 4 kicks it fired up!!

It runs great now. They idle was good and it fired the first kick every time. I went for a 3 hr trail ride and it ran near perfect. It continues to start every time first kick. I think that might be because of the more powerful spark?

In the 5-6k range wide open it stumbles a bit. I imagine that’s a herring issue?

For now I’m so happy to have it running and riding again. I forgot how fun it is!



On a separate note: I bought a ‘79 XT500 and was riding it in wet conditions. The day after I got the DT running the XT stopped and has no spark. I’m starting to wonder what will have no spark next lol

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No Spark after carb rebuild DT400 27 May 2019 08:42 #50

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Isaac wrote: I’m starting to wonder what will have no spark next lol


Don't look down!! :ROFLOL
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