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DT 250 Electrics Doing My Head In

10 May 2015 18:42
grumpy55
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DT 250 Electrics Doing My Head In #11
Hey Guys,
Thanks to all for the replies. And thanks for sticking with me on this. I believe at the end of the day it's going to be something simple.

Well you all seem to be pointing to the condenser or wiring short somewhere. So far I haven't found anything going to earth. I see what you mean about the 3 wires soldered onto the top of the condenser. From what I can see no bare wire is touching the condenser body. But I will try insulate those wires somehow and see what we get.

Is there any way I could have damaged the condenser when soldering those 3 wires onto the top. I held it in my thumb and forefinger while soldering and the body never got too hot to hold. Just a thought.

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10 May 2015 19:11
Bigdog302
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DT 250 Electrics Doing My Head In #12
the condenser is pretty tough. I always worry a bit about getting one too hot when soldering it but I never cooked one and they functioned well after the soldering. might try putting some electrical tape between the condenser and the wires. it does not take much to melt the insulation when soldering.

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
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31 Mar 2020 11:49 31 Mar 2020 11:51 by shredman.
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DT 250 Electrics Doing My Head In #13
I have exact the same problem with my 1979 DT25MX 1R7. Tried to rebuild my ignition with a new condenser, a ne Ignition Coil but I get no sparks. My biggest Problem. I soldered the 3 wires on the top of the new condenser but now the contact breaker a shorted to the ground. The shortend is coming from the ignition source coil. If I disoldered the cable from the ignition source coil, contact breaker and condenser is not shortend to ground. I checked the cable from the source coil with a multimeter against ground and it's shortenend. Is it normal that the ignition source coil is shortenend to ground ?? I buyed another DT250 ignition ground plate with both coils from ebay and it has the same effect, ignition source coil is shortend to the ground plate. I don't understand this. are the ignition source coils are burned or is it normal that they have connection to the ground plate ? Who can help me ?



Regards
Frank

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31 Mar 2020 12:33
MarkT
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DT 250 Electrics Doing My Head In #14
Frank, the source coil might seem "shorted to ground" but it's not. There is very little resistance change between points closed... zero ohms... and points open... maybe one ohm or certainly less than two ohms.

A "continuity tester" will beep with points open or closed. Some meters won't show the change accurately or at all. I find the old analog meters the best as long as they have an Rx1 scale.

Second part of this short video shows what I mean.


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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31 Mar 2020 13:26
shredman
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DT 250 Electrics Doing My Head In #15
Ok, but the question is why my spark plug ist not firing anymore ? I have no clue why. what should I check next to be save that no ground shortend is in the ignition system.

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31 Mar 2020 15:21
KJB
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DT 250 Electrics Doing My Head In #16
Basic stuff ,I know …...but is the spark plug new (and proven) ? I have just had a problem with a TW200 and the 2nd new plug fixed it . Original plug and first new plug were both faulty. I have also had stale fuel (not real old either) cause similar problems.
Hope you get it sorted - even if it is just for the satisfaction of beating the problem...……...

KB ( Australia)
'69 Yamaha DT1 S
'71 Yamaha DT1 .................................. '70 Suzuki T350
'72 Yamaha AT3 . ................................... '73 Suzuki T500
'86 Yamaha DT175 ..................................'68 Fuji Rabbit Hi Super 90
'06 Yamaha PW50
'94 Yamaha TW200...
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31 Mar 2020 17:50
MarkT
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DT 250 Electrics Doing My Head In #17
Why did you start changing parts in the first place? Did you have spark and it quit?

First thing is to just clean the point contacts. Even on new points (which you didn't mention if you had changed.)

And points should be grounded when closed with source coil disconnected.... you're not really clear about that.

The points systems are pretty reliable... so without knowing more about how the problem started or good pictures of how and what you're testing, it's going to be hard to help more.

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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31 Mar 2020 17:52
MarkT
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DT 250 Electrics Doing My Head In #18
Also it could simply be a bad key switch, kill button, or damaged wire.

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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01 Apr 2020 00:53 01 Apr 2020 01:48 by shredman.
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DT 250 Electrics Doing My Head In #19

Bigdog302 wrote: 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.


Hi,

I believe that I have a problem like this on my DT250 MX 1TR6. My spark is not firing anymore. Have changed the ignition coil, condenser and the contactbreaker against new one. Then soldered the three cables on the condenser (source coul, breaker and black/white) but now I didn't have any spark fire at all. I think I have a shortend to ground anywhere in the ignition. Is it normal that I have contact from the condenser soldered point to ground when all three cables are soldered ? If I dissolder only the cable from the source coil the shortend goes off. Is it normal that the source coil is shortend to ground without a connection to the condenser ? How can I get my spark firing again? how can I test the Engine off switch ?

Regards,
Frank

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01 Apr 2020 01:10 01 Apr 2020 01:12 by shredman.
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DT 250 Electrics Doing My Head In #20
Hi,

I had a spark before but it was weak and not on the moddle of the spark plug. I changed the ignition coil, breaker (was burned to much), the condenser and the spark plug. Points are cleaned with break cleaner.

you say: "And points should be grounded when closed with source coil disconnected.... you're not really clear about that."

It's true that I'm not really clear about that and the reason why I'm here :-)

what is the right behavior when the source coil is connected to the condenser ? When I connect the source coil to the condenser, the breaker is grounded all the time no matter if it's in closed or opened position. I think this is the main problem of my ignition or is it the normal behavior ?

Regards,
Frank

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