CDI from 02 250 on a 02 426???

6 replies to this topic
  • rufusz

Posted April 06, 2009 - 05:30 AM



Can I use the CDI from a 02 YZ250F on a 02 YZ426F ?
For a 250F yamaha code is :5SG-85540-00-00, for a 426 a 5SF-85540-00-00. Connectors fit, I've tried with one of my friends and the engine run fine, but didn't use it long time.


  • Larss

Posted April 06, 2009 - 05:34 AM


i would think it would work great if it is in good condition.

good luck!

  • grayracer513

Posted April 06, 2009 - 07:41 AM


The timing curve would be totally wrong, I would think.

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  • rufusz

Posted April 06, 2009 - 11:05 PM


Than too bad I already paid for it. Some guys in the 250 forum said that smaller engines have more advanced timing, so (if no pinging occurs) power curve could be more steeper...

Double drat, this is my second CDI failing on me, and I don't know why. Maybe that after market (possibly E-Line) stator/lighting coil is the reason.

  • rufusz

Posted April 10, 2009 - 01:23 AM



I've measure the resistance of the 2 coils that are shown in the Yami manual, for both normal is around 650 ohm, but I've measured for coil 2 only 0.44ohm. What is coil 1 and coil 2 used for? Both go into the CDI that's for sure :thumbsup: Just for you to know, the stator is not stock, it has a lighting coil, I think it's E-Light.

  • rufusz

Posted April 16, 2009 - 10:29 PM


Installed the CDI today, test run the bike in the backyard. Runs fine, but it sounds a little bit different. I believe :p Or maybe I've just forgot how it sounded before???? Today afternoon I will go out to the woods/track and see how it runs under load.
If the timing is now more advanced and/or timing curve is totally different, should I try to mess with the carb or it's pointless?

  • rufusz

Posted April 19, 2009 - 11:33 PM


So for general information sharing : the CDI from an 02 YZ250F works just fine on a 02 YZ426F. The bike seems more nervous then before, it hits more when going off from idle, or from 1/4 throttle, engine runs nice. But maybe that's due to new sparkplug, carb clean, and soldered CDI pickup-coil wire :p

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