Yeahaaaaa, popping on decel days are finally over. Woohoo


11 replies to this topic
  • 04 wr450

Posted February 07, 2016 - 10:57 PM

#1

Had my 04 450 for a couple of years and clocked up 8000ks ( mainly practicing wheelies).Bike has usual free mods,and includes yz450 exhaust system and cams.goes like a rocket.BUT....... That popping on decel was driving me nuts ,and was kind of embarrassing.I tried various things to eliminate it,such as adj mixture,make sure carby was clean,went up on pilot jet.still seemed lean at idle ,and mixture screw did not seem to do much.made sure manifold was tight ,and hot start cable was not hanging up.even took carb off at work and ultrasonically cleaned it,BUT ....same thing.spent hours searching for a solution on google ,but lots were saying the popping is normal etc.I eventually conceded defeat ,and just accepted it as normal.2 years later I am giving it a oil change and cleaning air filter when something popped in my mind.THE ACV ! I removed the cover and spring,and simply flipped diaphragm over and refitted spring and cover. I was a hour into my wheelie practice the following weekend when I realized,SHIT! I cannot believe it.NO MORE POPPING

  • Krannie McKranface

Posted February 08, 2016 - 03:20 PM

#2

The ACV ELIMINATES popping by richening the pilot circuit at closed throttle......



  • nrvale0

Posted February 08, 2016 - 06:08 PM

#3

Hot damn...I've been pulling my hair out for weeks with my '05 WR. Popping on decel and running super hot in tight technical stuff. Tried everything I could find...except this. Will give it a try!



  • 04 wr450

Posted February 08, 2016 - 06:33 PM

#4

The ACV ELIMINATES popping by richening the pilot circuit at closed throttle......

Exactly.but mine was not doing this.now it is blocked off pilot circuit is richer.no more bad idle,mixture screw works,and I can rev to limiter if I wish with no popping at all.



  • Krannie McKranface

Posted February 08, 2016 - 06:52 PM

#5

Exactly.but mine was not doing this.now it is blocked off pilot circuit is richer.no more bad idle,mixture screw works,and I can rev to limiter if I wish with no popping at all.

 

No, it's not blocked off, it's now on all the time....



  • 04 wr450

Posted February 08, 2016 - 10:49 PM

#6

Why is it there always has to be someone who tries to tarnish a triumphant occasion?the problem is FIXED

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  • GuyGraham

Posted February 10, 2016 - 09:45 AM

#7

It maybe it had been flipped already by a po and now you in effect put it back the right way round and do it is now functioning properly and richening the mixture on the overun and hence no more popping

Edited by GuyGraham, February 10, 2016 - 09:46 AM.


  • 04 wr450

Posted February 10, 2016 - 12:17 PM

#8

It was definitely installed correctly beforehand.The little Rod/stub on diaphragm was facing carby,so it could in and out of the small hole.now it is just pointing at cover and doing nothing.

  • GuyGraham

Posted February 11, 2016 - 10:06 AM

#9

It should really make the popping worse then

When functioning correctly it richens the mixture on the overun and so prevent popping

By what you have done, this is no longer happening so the popping should be worse (if you have gone from functioning ACV to an inoperable one) as the mixture will now be leaner than before on the overun and hence make the popping worse

 

If whatever you have done has worked for you, then that is all that matters, but what you have describe does not logically make sense



  • 04 wr450

Posted February 11, 2016 - 12:12 PM

#10

Yes I do agree.i was reluctant to touch it from the start because of this reason.now you can see why I am over the moon to have it suddenly sounding like a totally different bike after doing this simple step..

  • Ronnie.sensiba

Posted February 12, 2016 - 11:16 PM

#11

I had similar problems with my wr for about a year. Rebuilt the carb rejetted and dialed in the pilot circuit which made it better but it was still there. Finally found out that the header pipe was missing the gasket coming out of the engine. Even though it seemed tight it had a slight leak. If your having popping problems my first suggestion would be to replace that gasket.

  • 04 wr450

Posted February 12, 2016 - 11:47 PM

#12

Yes this was one of the first things I tried.i also sealed up where muffler slides on to header both with no fix.went out riding today.while out I removed cover on acv,flipped diaphragm over the (normal) way,just to prove a point.needless to say the popping came back on decel unless I partly opened choke.SO I turned diaphragm around the other way and NO MORE POPPiNG




 
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