Splitting cases on a YZ 426

5 replies to this topic
  • bfogelma

Posted October 23, 2011 - 08:00 PM


OK so long story short, I need to replace a crankshaft on my bike.
I am planning on doing the work myself, as I have done top ends before and watching videos online i think i can do it as long as im careful... hopefully haha.

My question is what miscellaneous parts will I need? I am going to replace the left half of the crank ( the part that the flywheel ultimately bolts to).

Should i be getting all new crank bearings too, and any other stuff i may be overlooking? It is a 2001 after all...If anyone has split cases on a four stroke before and has some insight please chime in... Thanks!

  • Yamaryder29

Posted October 24, 2011 - 06:08 AM


I did my 426 in april. I would replace any warn bearings. Do yourself a favor and replace all the oil seals along with the gaskets. Goto youtube and search johnnyshop. He has excellant videos of a 250f rebuild. The motors are the same design.

  • pscook

Posted October 24, 2011 - 06:51 AM


You will need a torx bit, can't remember the size. It's to remove the timing/stator plate to remove the counter balance shaft.

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  • YZ426_F

Posted October 24, 2011 - 08:04 AM


you need a Yamaha service manual. not a climer or any other cheap manual.
the Yamaha manual gives details on removing the motor, gives specs on everything.
you can pull everything apart in a way that you can remember how to put it back together (notes, pics, whatever helps) once you got everything apart you can makes a parts shopping list and order everything at once.

This is the only way to do it. if you only buy bearing a and b... you could find yourself half way done with the rebuild and need more parts.

  • grayracer513

Posted October 24, 2011 - 08:50 AM


Manuals are here:


  • bfogelma

Posted October 25, 2011 - 01:00 PM


thanks grayracer, the manual is going to help so much, the bike came with a clymer, and using one of those for reference is like shooting yourself in the foot trying to prepare to run a marathon.

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