Air cut valve on WR 426

4 replies to this topic
  • glamisbound69

Posted June 28, 2003 - 06:59 PM


Okay I went to motoman 393 page and there were many suggestions as to how to disable the acv. I chose #2 in order to stay with the stock 75 PAJ. According to procedures for this mod you must plug the vaccum port hole. Can anyone tell me which hole this is? Is it the one with the O-ring or is it the one with the trap door that the pin on the rubber diaphragm pushes in on or is it the one just to the right of that? Thanks.

  • jcbikes

Posted December 01, 2009 - 08:07 PM


I am looking to do this mod to my recently purchased 2002 wr426 and found this post. anyone have an answer?

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  • WR_Dave

Posted December 01, 2009 - 08:50 PM


The easiest way to disable it is to just flip the diaphram and spring the opposite way, so the spring is seated between the ACV cover and the diaphram and the pin is facing the ACV cover as well. It makes the jetting the bike correctly much easier. WR Dave

  • jcbikes

Posted December 02, 2009 - 08:41 AM


WR Dave,
Thanks for your response. What is the main benefit in doing this mod. Any negatives. Does it help in throttle response at low rpms or just help in jetting the bike. I have done all the other mods including the oring mod and saw this mod and was wondering about it.

  • WR_Dave

Posted December 02, 2009 - 10:27 AM


Doing this free mod makes the jetting easier to get dialed in and it cuts out the popping in the exhaust on decel as the air isn't allowed to bypass the carb once it is done. WR Dave


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