wr426 cylinder on yz426? possible differences

3 replies to this topic
  • philsyzf426

Posted October 15, 2014 - 08:38 AM


Hi will a wr426 cylinder fit yz426 and if yes is there any differences in them or the set up? I've been looking at 1 used that has a piston measuring 93mm were as mine was 97mm obvouisly I'd have it replated anyway with new piston etc on my full engine rebuild. Is there anyone who can give me exact specifications in mm of 4th and 5 gear from wr426 as I can get them made by a friend. Thanks

  • grayracer513

Posted October 15, 2014 - 08:58 AM


We've discussed this before:


1) Yes, a real WR426F cylinder is the same identical part as the YZ426F cylinder.


2) The stock bore for all 426 Yamahas is 95mm, thus,

  1. Yours had a big bore kit in it, so it's size is irrelevant
  2. The one you are looking at is for a 400. If you use it, you'll either have to get it bored 2mm over and replated, or change your connecting rod and turn your engine into a 400
  3. You cannot bore a 400 cylinder to 97mm

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  • philsyzf426

Posted October 15, 2014 - 11:09 AM


Thanks again greyracer i realise that my last barrel was overbored was just wanting to make sure that I could fit the wrf barrel as I thought most things identical. Can you point me in right direction to find out specs measurements for 4th and 5th gear for wrf. Or any info on Max range I could have the tranny made up? I need a little longer range for everyday use as I use it to get to work each day

  • grayracer513

Posted October 16, 2014 - 06:32 AM


The point is that the one you're looking at is not a WR426 cylinder.


No info on the gears except the part numbers.  The WR 5th is the highest geared option available.

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