03 yz450f no spark

5 replies to this topic
  • bmwhead2

Posted March 22, 2009 - 09:48 AM


I have a question? If your timing is off will you get spark?Or as long as the magnito or fly wheel is spinning around your stator you should get spark no matter what. New to this. I have replaced spark plug,cdi box,stator,ignition plug,checked kill switch,neutral switch and Tors. Any answers would be great. Im $600 in it and still no spark. I have not replaced magnito. Please help I am about to give up.

  • grayracer513

Posted March 22, 2009 - 10:15 AM


Ignition timing is not adjustable, and the only physical thing that can affect it is the key that indexes the flywheel. If indicated TDC on the flywheel agrees with the actual TDC determined by probing the piston through the spark plug hole, then the ignition should be timed right, and you should get spark.

Timing is adjusted on the fly by the CDI according to a trigger signal from the small coil in the stator assembly, rpm info, and information regarding throttle position from the TPS. If you have no spark, check the condition of the stator coils, the wiring, and the ignition coil before assuming the CDI has failed.

I have no idea what you are referring to by the term "Tors".

  • bmwhead2

Posted March 22, 2009 - 11:44 AM


Im sorry TPS not TORS thanks for the info.

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  • bmwhead2

Posted March 22, 2009 - 12:09 PM


I am top dead center and my timing mark lines up on fly wheel. What else could it be? I was kicking it over I decided to press the kill button in while I was kicking I recieved spark. Its like it is grounding out.So I read if you unplug you kill switch you should still get spark. I did that and nothing.

  • yz-moto

Posted November 28, 2013 - 07:54 AM


I know I'm reviving a pretty old thread here but I am wondering if this problem was every resolved? I am having the exact same issue. One spark when press kill button while kicking and that is it.

  • shortburb

Posted December 01, 2013 - 05:47 PM


My flywheel came apart in my 03...symptom was no spark....The flywheel looked like it was 2 pieces pressed together and it spun on itself. For whatever that's worth

Yamaha flywheel was $125..not too expensive.

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