yam wr cylinder swap

2 replies to this topic
  • potman1980

Posted April 24, 2012 - 06:40 AM


hi there,

i'm about to start what i think will be a serious project, but i'm a little stuck on the dimentional side of things.
i'm trying to build a 450 motor using a 400 short stroke bottom end and 450 head and cylinder.

i'm not sure if you van fit the wr/yzf 450 cylinder onto the 400/426 crank case, or failingtht can the 426 cylinder be bored out to 98mm from the 95mm STD.

i will be posting pics of the project as i go on the yamaha wr section if anyone is interested in watching the progress.

thanks for any help in advance.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted April 24, 2012 - 07:06 AM


Given the fact that the largest kits that were ever offered for the 426 were 444cc kits, (97mm bore) I would doubt that it's safe to run the 426 cylinder out to 98. A 450 can be bored to 98, however. IF you can stand a 450 cylinder on the 400 crankcase (I have heard you can, but the source is unreliable), and you were to do that, you'd end up with 452cc. IMO, it's a long way to go for 8cc more than you'd get with a 444 kit.

  • aclown

Posted April 27, 2012 - 12:12 PM


I have a 400 bored out to the 444 and I love it. The next step that I am aware of, is you can get the crank stroked a additional 2mm which I think brings you to around 468 cc. The place I saw the does the stroking of the crank is http://www.powroll.c...A_YZFWR426F.htm
I haven't worked with them or heard any feedback on them, so you may want to research them a little or give them a call.

Related Content


Michigan Motocross Tires by 288yz450

Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  35 replies

YZ450F 03 Sparks driving me crazy by SirAttard

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 5 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.