99 WR400F Conversion

3 replies to this topic
  • trickwarrior

Posted March 04, 2008 - 06:38 AM


Ok, First off I have read a lot bout this subject in here already. My questions is this. I 've a 99 wr400 that needs to have the crank, or at least a rod and bearings. I want to replace the entire rod and an wondering if I can just drop in a 426 crank. My jug has been resleaved and has room to be bored over to the 426 slug. Can I just buy a new crank for a 426 and drop it in there??? What others parts will I need to make it happen? Thanks in advance for any help and sorry for reposting this question.....

  • brt 426

Posted March 08, 2008 - 04:12 AM


Try this link


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  • ncampion

Posted March 08, 2008 - 08:34 AM


The 426 crank is the same stroke as the 400. The increase is due to the larger bore. Best bet is to have your crank rebuilt with the 426 rod since you already have your cylinder bored to the 426 specs. This way you get the stronger 426 pin also.

  • Birdy426

Posted March 08, 2008 - 05:10 PM


By the time you pay for the press work and alignment, it's about a push cost-wise to rebuild your 400 crank with a new 426 rod kit or buy a 426 crank from the TT store. However, the earlier cranks used a woodruff key to keep the primary drive gear from spinning on the crankshaft, and the 426's (at least from 01 up) use a splined shaft, which means that you would need to buy a primary drive gear as well. Depending on how worn your gears are, it may also be a good idea to replace the primary driven gear (that's riveted to the clutch basket) as well. If it were me, I'd go for the new crank and primary drive gear from the TT store, and see how well it meshes with your old driven gear...it will prpbably be fine, and you get the piece of mind of having new parts.


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