Changing a YZ400F to a YZ426F

8 replies to this topic
  • Fast_Yamaha

Posted August 24, 2005 - 07:06 AM


I own a 1998 YZ 400F and have rode my friends YZ 426F and like it a lot more than my 400. I was asking around to see if I could change the piston and bore to accept the 426 piston. Will the 400 rod fit the 426 piston, or do I have to split the case and change the rod? Thanks for your help. :D

  • nimiz1

Posted August 24, 2005 - 07:59 AM


try this

  • Vick115

Posted August 24, 2005 - 10:05 AM


I have an '02 YZ426 thats practically brand new Ill sell ya. As much as I love the bike, The WR450 just seems to always be the bike I ride.

  • Hick

Posted August 24, 2005 - 12:41 PM


Will the 400 rod fit the 426 piston, or do I have to split the case and change the rod? Thanks for your help. :D

Pretty sure you need to change the rod, but I have not personally done this swap so I can't be 100% certain. My understanding is that the small end is bigger on the 426.

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  • Joel

Posted August 24, 2005 - 12:42 PM


The 426 has a bigger diameter wrist pin. The cylinder bolts right up.

  • cobra427

Posted August 24, 2005 - 01:32 PM


What's up! My buddy has a 2002 426 and I've rode his bike a few times and yes it makes great power. My friend's bike is pretty much stock. I have a yz 400 with a big bore kit that takes it up to 420ccs' . That bore is on par with the 426. My bike has been rejetted, has a high performance exhaust and a high performance airfilter and it rips. I have never rode my bike and then rode his and felt mine was a step behind. My bike is heavier than his but other than that, they seem pretty similar. I think for you a simple big bore kit and relatively inexpensive & very common mods will get you where you want to be. If your really trying to set your bike up to identical specs of the 426 more power to you. :D

  • nimiz1

Posted August 25, 2005 - 12:46 AM


go to

  • Slowmotion426

Posted August 25, 2005 - 02:00 AM



  • Pincushion

Posted August 25, 2005 - 03:26 PM


You can have the 426 rod installed into the 400 crank and then bolt a 426 jug/piston on.

A friend of mine did this on his WR400. Eric Gorr did the crank work.

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