yz 400-426 heads?

5 replies to this topic
  • haydug

Posted November 18, 2006 - 10:11 AM


I'm pretty sure they are the same, but does anyone know for sure if a 1999 YZ 400 head will fit up to the 2003 YZ 426 models?

  • wapner666

Posted November 18, 2006 - 07:37 PM


Ummmm well the 2003 is a 450 so a '99 YZ400f head will not fit a 2003. A 2002, should but you could check the part numbers on one of the online parts fiche. I think yamaha of troy has one on their website. Good luck.

  • 1rkcooper

Posted November 19, 2006 - 10:10 AM


I haven't done this but I'm pretty sure they will fit on the 426. Here is a link to a web site with some info on converting a 400 to a 426. Check it out. http://www.powroll.c...A_YZFWR426F.htm

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  • Birdy426

Posted November 19, 2006 - 08:59 PM


The 400 head will fit the 426, and as already noted, not the 450. I picked up a rebuilt and ported 400 head from Eric Gorr for a screami' deal last winter, and it bolted right on my 426. The casting numbers are the same, but the part numbers are different on the parts fiche because the 400 head has a hole drilled in the intake side (on an existing boss) with a nipple pressed in that the 426 doesn't (something about the "octapus"). I just drilled it out and plugged it up with a bolt on the 426.


Posted November 20, 2006 - 01:58 PM


I have a 98' YZ400F and I rebuilt it with a 00' WR head. The only thing I had to do was drill the hole for the Hot Start. A 400 head will fit the 426. I think even the valves are the same except for metal type and one dimension that isn't critical. You should be golden.

  • haydug

Posted November 20, 2006 - 07:47 PM


10-4. I just bought a nice 1999 yz 400 that I am going to part out, and just trying to check on what parts do interchange between one another.

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