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
SEB416

WR 450 BIG BORE KIT TO 500

11 posts in this topic

Dirt Bike magazine did a WR470 kit article and test last year and loved the results. I just cant remember the issue. I will have to dig for it.

Share this post


Link to post
Share on other sites

Anybody know if the WR450 jug is compatable with the WR400 head? Or is this a possible swap with a complete top end?

Share this post


Link to post
Share on other sites

Anybody know if the WR450 jug is compatable with the WR400 head? Or is this a possible swap with a complete top end?

??? If you are wanting the larger bore (95mm), I believe you should be looking for a 426 cylinder not a 450(The bores of the 426 and 450 are the same). The 450 is all different and is not compatible.

Share this post


Link to post
Share on other sites

Right now I have a 426 jug on a 98wr400

it's bored out 2mm, so it's running 444cc I believe, 13:1

but if I want to go 500, can this jug be bored out 4mm? I thought that would be pushing it.

Share this post


Link to post
Share on other sites

Right now I have a 426 jug on a 98wr400

it's bored out 2mm, so it's running 444cc I believe, 13:1

but if I want to go 500, can this jug be bored out 4mm? I thought that would be pushing it.

I don't think 4mm over is possible. I think I saw a 3mm over and they were having a hard time keeping head gaskets in it. You can go with a Powroll 2mm stroker for like a 469cc motor, YZDAD1 (SP???) did this. It requires a custom thicker base gasket to run with aftermarket and non modified OEM pistons. Talk to Cometic for the gasket, should be roughly 1mm thicker.

The 450 gets its extra CC's from a longer stroke, not a bigger cylinder bore. :)

Share this post


Link to post
Share on other sites

Right now I have a 426 jug on a 98wr400

it's bored out 2mm, so it's running 444cc I believe, 13:1

but if I want to go 500, can this jug be bored out 4mm? I thought that would be pushing it.

I don't think 4mm over is possible. I think I saw a 3mm over and they were having a hard time keeping head gaskets in it. You can go with a Powroll 2mm stroker for like a 469cc motor, YZDAD1 (SP???) did this. It requires a custom thicker base gasket to run with aftermarket and non modified OEM pistons. Talk to Cometic for the gasket, should be roughly 1mm thicker.

The 450 gets its extra CC's from a longer stroke, not a bigger cylinder bore. :)

And doing this would put you within 3cc of an overbored 450. If you are looking for more, some custom head work and some hotcams may be in order. :D

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