YZF426 cylinder head+cylinder fit on WR400?


5 replies to this topic
  • Magic_johnson

Posted December 21, 2007 - 08:30 AM

#1

Hi!

The cylinder head on my wr400-99 is a mess since a valve broke, and a complete new is very expensive.
I can get hold of a yzf426-00 cylinder head + cylinder for a good price, so my queston is if it will fit "bolt on" on my wr400?

(sorry for my english)

  • Birdy426

Posted December 21, 2007 - 09:58 AM

#2

Not quite a bolt on. The 426 piston uses a larger wrist pin and bearing, so you would need to rebuild your crank with a 426 connecting rod (big end is the same, so it's a simple swap). Rod kit should be about a buck and a quarter, and about a buck to rebuild and true the crank.

There is also a vacuum port on the 400s for the Hot Start Octopus that isn't there on the 426s. The boss for the port is there, you would need to drill it out and press in a brass nipple or tap it and thread in a brass nipple to provide vacuum for the octopus.

  • Magic_johnson

Posted December 21, 2007 - 10:16 AM

#3

Not quite a bolt on. The 426 piston uses a larger wrist pin and bearing, so you would need to rebuild your crank with a 426 connecting rod (big end is the same, so it's a simple swap). Rod kit should be about a buck and a quarter, and about a buck to rebuild and true the crank.

There is also a vacuum port on the 400s for the Hot Start Octopus that isn't there on the 426s. The boss for the port is there, you would need to drill it out and press in a brass nipple or tap it and thread in a brass nipple to provide vacuum for the octopus.


Thx for the reply!
Okey, sounds like something that´s possible to do.
Have you done this yourself or know anyone else? If yes, did the piceses run well togheter?

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  • 1rkcooper

Posted December 21, 2007 - 09:39 PM

#4

You should be able to get your answer here.

http://www.powroll.c...A_YZFWR426F.htm

  • Birdy426

Posted December 21, 2007 - 09:41 PM

#5

Thx for the reply!
Okey, sounds like something that´s possible to do.
Have you done this yourself or know anyone else? If yes, did the piceses run well togheter?


I went kinda backwards from you...I put a big bore 426 cylinder (444 cc) and400 head on my 426, so I had to plug the vacuum port.

I've had 4 stroke cranks rebuilt as well, bt not my own...

  • rockieman

Posted December 23, 2007 - 06:36 PM

#6

There is also a vacuum port on the 400s for the Hot Start Octopus that isn't there on the 426s. The boss for the port is there, you would need to drill it out and press in a brass nipple or tap it and thread in a brass nipple to provide vacuum for the octopus.[/QUOTE]

I rebuilt my 99 400 to a 426 by swapping the crank, rod, piston, cylinder. I stuck with the 400 head because of the SS valves vs. Titanium.
As far as the Octopus crap....go to your local auto parts store and plug that vacuum leak looking for a place to happen off.




 
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