used wr426 mods

4 replies to this topic
  • ktmlane

Posted December 16, 2008 - 07:15 AM


hope someone can help. just bought a used 2002 wr 426f and would like to know all the mods and jetting i need to do.never owned a yamaha before and any help would be appericated. thanks guys:ride: :thumbsup: :smirk:

  • tcmII

Posted December 16, 2008 - 04:54 PM


I'm surprised you lasted to 7:45 (my time) without someone screaming at you. Everything you need can be found at the top of this forum. But to get you started and assuming that none have been done:
1. Change the throttle stop to ZY.
2. Remove the exhaust baffle and replace with a PMB or Yamaha insert.
3. Remove the air cleaner cover.
4. Search on the YZ timing or auto-decompression cam.
5. Probably go up a size on the Main.
6. Search for the Grey Wire mod.

Do this things and your WR will almost make YZ power.

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  • GCannon

Posted December 17, 2008 - 09:25 AM


My List for you:
1. read stickies at top of this forum
2. perform free mods to your 426
3. Tune Accelerator pump system using the vast resource of info on this forum
4. jet carburetor for your altitude and temp refer to jetting data base for starting point
5. Very carefully tune your idle mixture for easier starting.
6. service all bearings
7. start thinking about customizing your suspension.

  • byggd

Posted December 17, 2008 - 01:16 PM


IMO the best mod you can do!!

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  • ktmlane

Posted December 18, 2008 - 07:25 AM


thanks guy your info. is appericated very much


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