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runs with key off

  • richrd
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runs with key off was created by richrd

working on a '72 250 (dt) that has been butchered in every way possible.  Where I'm at now is that it runs with the key off and stops with the key on.

It should be as simple as the wire from the rectifier going to the coil?

The Japanese wiring diagrams are a joke, and I dont know if the wires are the correct color or if they have been changed,

So before i go and pull all the wires and start over,  do you have any guidance?

thanks
Rich 
The following user(s) Liked this Post: Jewelkutter
08 Jun 2023 11:00 #1

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Replied by Sneezles61 on topic runs with key off

Just reading an electrical schematic is tough.. period.
But the Japanese schematics for these old bikes are good in my book. It’s helped me with a RT2 (1972].
Rectifier is used to change AC voltage to DC for the battery side.
Your switch must have some wires hooked up wrong. GR8 Uncle AL has the schematic written out somewhere in the depths of this forum. I’d suggest doing a search. Do spend time studying the wire schematics.. a magnifier will help. Follow each wire. The worst you’ll do is be cross eyed for a few hours.
Sneezles61
The following user(s) Liked this Post: Ht1kid, Jewelkutter
08 Jun 2023 14:12 #2

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Replied by MarkT on topic runs with key off

It has a magneto ignition.  There is a wire from the points to the ignition coil.  (highlighted in red below, wire should be black with white stripe but is sometimes just black). 

Ignition is shut off by a wire that is teed into the wire between the points and coil.  That wire goes to ground.  When the switch contact are closed, the connection is made to ground and spark is killed.  When the switch contacts are open, the connection to ground is broken and you have spark.

Someone could have installed a different switch that is for a "battery ignition" bike?..  On a battery ignition switch, the contacts close when key is on to power the ignition.  On your magneto bike, the contacts open when the key is on to stop grounding out the points wire. 

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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
The following user(s) Liked this Post: RT325, Ht1kid, Jewelkutter
08 Jun 2023 17:29 #3

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Replied by Gr8uncleal on topic runs with key off

"GR8 Uncle AL has the schematic written out somewhere in the depths of this forum. I’d suggest doing a search."


Here we go - post #2.

72 DT2 key switch wire diagram - Vintage Enduro Discussions (yamaha-enduros.com)
The following user(s) Liked this Post: Ht1kid, Jewelkutter, Sneezles61
09 Jun 2023 02:10 #4

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