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DT 250 Electrics Doing My Head In

16 Apr 2015 17:03
grumpy55
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DT 250 Electrics Doing My Head In #1
Hey Guys,
I am new here and in need of help.
I have a 1974 DT 250 A.
Have owned the bike for over 25 years but has been in storage the last 15 awaiting restoration.
It has been started in that time and moved to different locations.
A month ago went to start it and nothing. So what did I expect after all this time ha ha.
Anyway I discovered I had no spark so went down the road of trying to find out why.
I replaced the points / condenser / coil. All to no avail.
Read a few posts on here and did the tests recommended. All came up good except for a very important one.
I have no AC voltage from the wire going to the primary side of my coil.
Can someone tell me what I am overlooking here. Or point me in the right direction for troubleshooting this problem.
I'm not a mechanic / auto electrician and have a basic multimeter for testing purposes.

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16 Apr 2015 17:49 16 Apr 2015 17:51 by Bigdog302.
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DT 250 Electrics Doing My Head In #2
I rarely see source coils go bad. I would test the points themselves and make sure they have continuity when closed and infinite when open. other than that you can see if the black/white stripe wire is shorted to ground. with the ignition switches both on there should be no shorts and will only show short to ground with the ignition switches off.

another thing to try is disconnect the ignition switch wire from the throttle from the harness and checking for spark. I have seen those short to ground before. might also try a known good spark plug as I have seen spark plugs fail if they were ran a short time on the engine and left to sit afterwards. in other words a fouled plug.

you can also check the ignition coil. it should show 3 ohms with the meter connected to the Black/White stripe wire and ground on the coil itself. might also check and make sure the coil itself has good ground.

2 1968 DT1s,1970 RT1M,1970 DT1C,1971 RT1B,1971 Honda Z50K2,1974 DT100A 1974DT250A,1974 Honda MT250,2 1975 DT400Bs,1975 Honda CR250M1,1978 DT175E,1979 Honda CR250R.
Dave
Jesus is Lord!
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16 Apr 2015 22:44
MarkT
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DT 250 Electrics Doing My Head In #3
With the points installed in the bike, the resistance of the black/white wire will change as the points open and close but the meter will not show "infinite" with the points open. With some meters, it's hard to measure the change.

My suggestion is to list the exact "recommended" tests you've tried. Taking pictures of how you had the meter connected (or a written description) and the results you saw would be helpful

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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19 Apr 2015 21:28
grumpy55
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DT 250 Electrics Doing My Head In #4
Thanks to both of you for your replies and ideas.
Tried your suggestions and still no spark.
Been over the whole bike as far as wiring goes and can't find a short anywhere.
No power to the black / white wire to the coil has me beat. Going back to dismantle the ignition switch and kill switch to check.
Will let you know how I get on.
Thanks again

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23 Apr 2015 22:44
grumpy55
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DT 250 Electrics Doing My Head In #5
Well I'm Back Again.
One more shot before I give up.
Got another tester. This one analogue with dial.
Do not see any movement in needle when points open and close. Reading 5 ohms constant.
Also have constant continuity light on meter with points closed and open. Is this normal or is it a problem.
Thanks in advance to anyone who replies.

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23 Apr 2015 22:53
Makotosun
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DT 250 Electrics Doing My Head In #6
My first thought is if you can post up a clear picture of the stator with the flywheel off? In particular how the wiring is?

My guess is that you have something as simple as an insulating washing on the wrong side of a wire grounding things out. It was that simple on a recent thread - Look at this:

yamaha-enduros.com/index.php/kunena-2014...t2-spark-issue#14063

Different bike, but the system is nearly identical and subject to the same issues.

IF it isn't one thing, it's another.
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24 Apr 2015 04:36
bluntz465
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DT 250 Electrics Doing My Head In #7
If there is no power out of the primary coil the first thing to check is the main ground,before you go buying anything.

1957 Cushman Eagle 1969 Honda 90 ATC 1969 Honda CB250
1973 Yamaha AT3 1974 Kawasaki KH440 1974 Honda XR75
1975 Suzuki TS75 1975 Kawasaki GreenStreak 90 1975 Suzuki GT550
1975 Suzuki TS250 1976 Suzuki GT550 1976 Indian Chief
1976 Yamaha YZ80 1978 Yamaha IT175 1980 Suzuki GS550
1982 Yamaha IT465J
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04 May 2015 23:11
grumpy55
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DT 250 Electrics Doing My Head In #8
Sorry for the delay in getting back to the discussion guys.
Have attached a couple of pics as requested.
Pulled the points and checked them out. All insulators seem to be in place correctly.
One thing on the points continuity (open and closed). It only occurs with the wire from the condenser attached to the points. Disconnect this wire and points function fine.
Any ideas where else to look or what to test.
Look forward to hearing from you.


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04 May 2015 23:27 06 May 2015 16:08 by Bigdog302.
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DT 250 Electrics Doing My Head In #9
it sounds like you got a short to ground somewhere to the points and condenser. BTW is the ignition and kill switches set to the run position? if either switch is closed it will show a short.

another possibility is the wires themselves insulation may have burned through,try lifting the wires away from the condenser with the VOM hooked up and block open the points,it should drop from continuity back to what value the source coil itself has.

2 1968 DT1s,1970 RT1M,1970 DT1C,1971 RT1B,1971 Honda Z50K2,1974 DT100A 1974DT250A,1974 Honda MT250,2 1975 DT400Bs,1975 Honda CR250M1,1978 DT175E,1979 Honda CR250R.
Dave
Jesus is Lord!
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06 May 2015 13:27
Rexs Speedshop
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DT 250 Electrics Doing My Head In #10
Those wires stretched over the condenser, soldered to the centre - they aren't shorting to earth due to the soldering iron making the insulation soft?

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