1973 Yamaha DT 250 magneto test

4 replies to this topic
  • jasonlion54

Posted July 21, 2008 - 09:00 PM


I have a 1973 Yamaha DT 250 with no spark. I have a suspicion that the magneto has gone bad, but the wiring harness is a mess and the coil doesn't look so good either. I can't get a reading on my multimeter anywhere, so I figured I would start at the stator and then work my way to the plug.

Where should I put the test leads of my multimeter and what numbers should I expect? Also, should I be able to get any voltage anywhere if I kick the bike over while using the voltmeter? Thanks for any help you can give.

  • pwrpapa

Posted July 22, 2008 - 02:35 PM


maybe the points are bad or a bad ground wire.

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  • JunkmanKX250

Posted July 22, 2008 - 07:27 PM


I would check the point gap first. You should be able to put your meter on the green or red wire and to ground and get something out of it. Make sure the point gap is set first or you will not get anything out of the stator.

  • jasonlion54

Posted July 27, 2008 - 07:39 PM


Figured it out. The bike was wired wrong. Testing the leads coming straight out of the magneto with a DIGITAL multimeter while kicking the bike over by hand yielded no results at all from any of the wires. Turns out that a digital multimeter doesn't register fast enough to pick up those short, low power bursts. I went and bought an ANALOG multimeter and sure enough, one of the wires coming out of the magneto was making the needle on the multimeter jump a little bit, so I hooked that wire straight up to the coil and fired the bike up.

Thanks for your help guys, and hopefully what I learned can be useful to someone else.

  • CensoredList

Posted July 09, 2013 - 05:10 PM


Hey there, I have a '74 with the same problem, What color was the wire you hooked up to the coil?



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