Posted by JTravis via MotorcycleKB.com on May 2, 2008, 1:39 pm
I have a '74 Yamaha 250 enduro - the wireing harness is all screwed up and
half missing. Can I wire the mag and points to the spark coil to run the
engine directly without a wiring harness and battery ? I don't need all the
lighting etc. Can anyone tell me how to do this ?
Thanks
Jim Travis
--
Message posted via http://www.motorcyclekb.com
Posted by . on May 2, 2008, 3:14 pm
e:
> I have a '74 Yamaha 250 enduro - the wireing harness is all screwed up and
> half missing. �Can I wire the mag and points to the spark coil to run the
> engine directly without a wiring harness and battery ? �I don't need all the
> lighting etc. �Can anyone tell me how to do this ?
Your Yamaha has a simple energy transfer magneto. In an energy
transfer magneto, the low voltage source coil is inside the permanent
magnet flywheel. The high voltage coil is mounted on the frame to get
it away from engine heat and vibration.
There are three coils in the ET magneto. Two are lighting coils and
the third coil is the source of low voltage for the ignition coil.
One end of this coil is already wired to the points and condensor.
Run the wire from the other side of the low voltage coil to the
ignition coil on the frame. A wire already existed for this energy
transfer function and may still exist.
The ignition coil probably has a ground wire going to the frame to
complete the energy transfer circuit.
You will want a way to turn the ignition off. A wire from a handlebar-
mounted killswitch to the ignition points will complete your
installation.
Posted by JT on May 2, 2008, 11:52 pm
JTravis via MotorcycleKB.com wrote:
> I have a '74 Yamaha 250 enduro - the wireing harness is all screwed up and
> half missing. Can I wire the mag and points to the spark coil to run the
> engine directly without a wiring harness and battery ? I don't need all the
> lighting etc. Can anyone tell me how to do this ?
>
> Thanks
> Jim Travis
>
I had a DT125 in 1974. I found a shop manual for 125AT2 and 175CT2 which
worked for me. I the diagrams can be of help let me know and I'll scan
them for you.
Posted by JT on May 2, 2008, 11:58 pm
JTravis via MotorcycleKB.com wrote:
> I have a '74 Yamaha 250 enduro - the wireing harness is all screwed up and
> half missing. Can I wire the mag and points to the spark coil to run the
> engine directly without a wiring harness and battery ? I don't need all the
> lighting etc. Can anyone tell me how to do this ?
>
> Thanks
> Jim Travis
>
I had a 1974 DT125, and found a shop manual for the 125AT2 and 175CT2
series. If you think the diagram would help, let me know and I'll scan
it and email it.
Posted by JTravis via MotorcycleKB.com on May 4, 2008, 8:17 pm
JT wrote:
>> I have a '74 Yamaha 250 enduro - the wireing harness is all screwed up and
>> half missing. Can I wire the mag and points to the spark coil to run the
>[quoted text clipped - 3 lines]
>> Thanks
>> Jim Travis
>I had a 1974 DT125, and found a shop manual for the 125AT2 and 175CT2
>series. If you think the diagram would help, let me know and I'll scan
>it and email it.
Thanks - The diagram may clear this up for me. The earlier post sounded
like it would be a snap but the coils in my magnito are tied together and I
don't understand this. One is for lights and the other should only fire the
spark coil. Anyway if it is not too much trouble send me the diagram.
Thanks
Jim Travis
--
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http://www.motorcyclekb.com/Uwe/Forums.aspx/bike/200805/1
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> half missing. �Can I wire the mag and points to the spark coil to run the
> engine directly without a wiring harness and battery ? �I don't need all the
> lighting etc. �Can anyone tell me how to do this ?