HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
Magic_johnson

YZF426 cylinder head+cylinder fit on WR400?

6 posts in this topic

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)

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites
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?

Share this post


Link to post
Share on other sites
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...

Share this post


Link to post
Share on other sites

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.

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.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0