2010 Spark Plug Cap Resistance

4 replies to this topic
  • iveyyam450f

Posted March 05, 2012 - 10:11 AM


Does anyone know what the resistance should be for the spark plug end cap on a 2010 YZ450f.

  • grayracer513

Posted March 05, 2012 - 10:41 AM


That's the ignition coil. Primary resistance (connect meter to terminals 1 & 2) is 3.57 - 4.83 Ω. Secondary resistance (from terminal 1 (orange lead) to the plug terminal) is 10.71- 14.49 KΩ.


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  • iveyyam450f

Posted March 07, 2012 - 06:39 AM


I may have said that worng. I am looking for what the resistance of the resistor inside of the spark plug cap should be.

  • grayracer513

Posted March 07, 2012 - 09:57 AM


Ah, that's right, the '10+ models went back to a separated coil set up. That should be listed in the manual if there is one, but there isn't any indication that there is. Since no value is given, I would assume it is simply a solid conductive terminal. There isn't a need for resistance at that point in any case when the correct resistor plug is used. The plug cable is another matter, and might be either solid wire or a resistor type.

  • iveyyam450f

Posted March 07, 2012 - 10:55 AM


I could not find it anywhere in the manual. There is a resistor is there and it tested at 10k ohm resistance. I have a sort of intermittent "rough" sort of a misfire at idle. It kind of comes and goes. Someone told me they heard of those resistors having high resistance in them causing that kind of concern and that the resistor should be a 5k ohm resistor.

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