WR 450 air cut valve


8 replies to this topic
  • Lowedog

Posted April 01, 2004 - 06:05 PM

#1

Has anyone disabled theirs yet? If so is there anything to gain in doing so?

Thanks in advance,
Lowedog

  • Lowedog

Posted April 02, 2004 - 01:43 PM

#2

Bump- anyone?

  • Boss302

Posted April 02, 2004 - 03:17 PM

#3

I disabled mine, but couldn't really tell a difference anywhere. Maybe I did it wrong. When I took it apart, it looked like the plunger was pushing the white valve inward when there was no or low vacuum in front of the slider. Thus, when there is high vacuum, the diaphragm pulled the plunger and allowed the white valve to move outward.

I believe that valve out causes a richer mix, and vavle in causes a leaner mix. I do not know if my understanding of this valve is correct or not.

I disabled the mechanism by removing the spring and reversing the plunger and diaphragm, then reinstalling the cover.

If anyone knows if this is correct or not, I would sure like to hear from you.

  • 5spoke

Posted April 02, 2004 - 06:11 PM

#4

I tried reversing the rubber diaphram, but didn't feel any diff. I put it back like it was.

I'm not convinced its a bad thing to have, if it stops a lean backfire on deceleration. :)

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  • Lowedog

Posted April 02, 2004 - 08:11 PM

#5

I kind of feel the same way, that it may not be a bad thing. I have a slight bit of rough condition when just cruising with the throttle barely open. I was told by James Dean that the ACV can cause that. Kind of like going from rich to lean at a steady throttle position when it is just barely past idle.

Later,
Lowedog

  • lipskid

Posted April 03, 2004 - 08:12 AM

#6

I think I read somewhere in past discussions that disabling it can help with diagnosing jetting, but it's not really a performance mod.

  • N7SLC

Posted April 03, 2004 - 11:45 AM

#7

I disabled mine, but couldn't really tell a difference anywhere. Maybe I did it wrong. When I took it apart, it looked like the plunger was pushing the white valve inward when there was no or low vacuum in front of the slider. Thus, when there is high vacuum, the diaphragm pulled the plunger and allowed the white valve to move outward.

I believe that valve out causes a richer mix, and vavle in causes a leaner mix. I do not know if my understanding of this valve is correct or not.

I disabled the mechanism by removing the spring and reversing the plunger and diaphragm, then reinstalling the cover.

If anyone knows if this is correct or not, I would sure like to hear from you.


The air cut off valve richens the low-speed jetting on deceleration
to keep the engine from popping or backfiring. A good idea, but it
makes the low-speed jetting difficult.

If you removed/by-passed it and saw no difference, that indicates that
your low-speed jetting is correct.

Well done. :)

  • Boss302

Posted April 04, 2004 - 02:48 AM

#8

I going to ride it today without the ACV operable, and then reinstall to see if there is a difference going backwards.

  • RichBaker

Posted April 04, 2004 - 08:59 AM

#9

The correct way to disable it would be to put a spacer of some sort in place of the spring. The little tit on the face of the diaphram is what blocks the fuel passage. When the manifold vacuum is high enough to overcome the spring, it pulls the tit out and opens the passage...




 
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