O-ring carb mod ????


18 replies to this topic
  • Summit

Posted February 12, 2008 - 11:53 AM

#1

I keep reading about this mod but I can't seem to find a detailed explanation or pics to describe it. Can anyone steer me in the right direction for more information? Thanks.

  • KennyMc

Posted February 12, 2008 - 12:49 PM

#2

http://www.thumperta...ad.php?t=604077

Here is a picture of it. It's the o-ring right above the spring with the blue on it.

  • byggd

Posted February 12, 2008 - 01:31 PM

#3

I'm trying to remember. Does this mod apply to pre 03?

  • GCannon

Posted February 12, 2008 - 02:24 PM

#4

I'm trying to remember. Does this mod apply to pre 03?


I think not (however I could be wrong)

WR 400 = taffy mod
WR 426/400 = BK Mod
WR 450 = Leak jet, Oring mod, diaphram change

I think this is how they apply

  • byggd

Posted February 12, 2008 - 03:08 PM

#5

I think not (however I could be wrong)

WR 400 = taffy mod
WR 426/400 = BK Mod
WR 450 = Leak jet, Oring mod, diaphram change

I think this is how they apply

Thanks! Already did the BK mod so I guess it's good to go :applause:

  • GCannon

Posted February 12, 2008 - 03:39 PM

#6

Thanks! Already did the BK mod so I guess it's good to go :)


You already new that!:applause:

  • crooks420

Posted February 12, 2008 - 09:25 PM

#7

So do I assume correctly that the o-ring mod will apply to my 05 WR450??? Who has done this, and how do you like it?

Jesse

  • Summit

Posted February 15, 2008 - 11:44 AM

#8

So do I assume correctly that the o-ring mod will apply to my 05 WR450???

I'm wondering about this too. Anyone??

  • Pooley

Posted February 15, 2008 - 12:42 PM

#9

Another O-ring mod discussion. In this thread there is also the direct link to Redbeard's pdf

http://www.thumperta...ad.php?t=521725

For my 01WR426, O-ring mod was FAR superior to the BK mod, which is now disabled.

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  • beezer

Posted February 15, 2008 - 02:32 PM

#10

I noticed in the Dirt Bike article on the the 08 WR450 Dr. D. turned the accel pump screw in half a turn.

A buddy tried it on his and said it made his bike have much better throttle response.

I don't know what the screw does to be honest.

  • MotoGoalie

Posted February 15, 2008 - 02:47 PM

#11

I noticed in the Dirt Bike article on the the 08 WR450 Dr. D. turned the accel pump screw in half a turn.

A buddy tried it on his and said it made his bike have much better throttle response.

I don't know what the screw does to be honest.



It times (sets) when the accellerator pump gives the squirt of gas as the throttle is opened up.

If you take the carb off and twist the throttle, it shoots a stream of gas, right into your eye and then you erupt into a ball of flame.

  • GCannon

Posted February 15, 2008 - 03:38 PM

#12

Pooley:
what was the differnce in performance between the BK mod and the Oring mod? It sounded like you made significant jetting changes after the oring mod.

I may not be understanding correctly (supriseing I know) the oring mod as Readbeard describes it makes the AP squirt duration longer then uses the leak jet to reduce the AP squirt volume? How do you reduce the squirt volume on the 01 WR? or do you adjust the jetting to compensate?

How do you adjust the AP squirt timing with the Oring mod same as the BK Mod, in particular the initial squirt timing?

Thanks

  • beezer

Posted February 15, 2008 - 06:06 PM

#13

If you take the carb off and twist the throttle, it shoots a stream of gas, right into your eye and then you erupt into a ball of flame.


I guess to make this work I should be smoking a stogie when I do this.

I think the o-ring does the same thing as the stiffer spring that comes with the R & D Powerbowl.

The JD kit I had came with two o-rings a skinny one and a fat one.

The directions said the fat one gave it better throttle repsonse then the skinny one.

  • yz-dwg

Posted February 16, 2008 - 05:42 AM

#14

[quote name='beezer']
The JD kit I had came with two o-rings a skinny one and a fat one.
QUOTE]

I used the skinny one and like what it did to my throttle responce.

  • byggd

Posted February 16, 2008 - 09:54 AM

#15

Another O-ring mod discussion. In this thread there is also the direct link to Redbeard's pdf

http://www.thumperta...ad.php?t=521725

For my 01WR426, O-ring mod was FAR superior to the BK mod, which is now disabled.

I think not (however I could be wrong)

WR 400 = taffy mod
WR 426/400 = BK Mod
WR 450 = Leak jet, Oring mod, diaphram change

I think this is how they apply


Q: Is a JD Jetting Kit worth it/what does it do?
A: The JD Jetting Kit contains two triple-tapered needles that are bike specific and give you a year-round solution to the WR’s jetting needs. The kit also contains an assortment of main jets and several O-rings to modify your AP linkage on the '03's and up for better throttle response.



Wait, so the o-ring mod does apply to the wr426 as well :applause:

  • bg10459

Posted February 16, 2008 - 11:02 AM

#16

Wait, so the o-ring mod does apply to the wr426 as well :applause:

I believe so, however, without a leak jet you won't be able to bleed the additional pressure the o-ring will create at the AP nozzle.
I'm pretty well versed in the O-ring mod, but not with the older WR's, so I cold be totally wrong.:)

  • bg10459

Posted February 16, 2008 - 11:04 AM

#17

How do you adjust the AP squirt timing with the Oring mod same as the BK Mod, in particular the initial squirt timing?

The AP timing screw still dictates the start of the squirt, no matter which mod you do.

  • Pooley

Posted February 17, 2008 - 08:24 PM

#18

Pooley:
what was the differnce in performance between the BK mod and the Oring mod? It sounded like you made significant jetting changes after the oring mod.

I may not be understanding correctly (supriseing I know) the oring mod as Readbeard describes it makes the AP squirt duration longer then uses the leak jet to reduce the AP squirt volume? How do you reduce the squirt volume on the 01 WR? or do you adjust the jetting to compensate?

How do you adjust the AP squirt timing with the Oring mod same as the BK Mod, in particular the initial squirt timing?

Thanks


The difference in performance was huge. Instead of goofing around trying to time the squirt perfectly like I had been (BK mod), the O-ring mod basically squirts all the time whenever the throttle is opened. Maybe I had my squirt WAY off, but the bike was closer to an open pipe feel with the O-ring. VERY responsive and much less bogging/stalling at low RPM. I was a happy customer about 30 seconds after starting the bike.

As far as jetting "changes", I actually only changed my pilot from a 42 to 45. I just switched pilot and mods and went for it. There is no leak jet to adjust, however I believe we could get a different diaphragm or spring to adjust the pressure. I didn't change a thing with the diaphragm.

The initial squirt timing, such that it just misses the slide I had set previously, and did not adjust it at all. I never re-checked, but would assume it still just barely misses the slide. That screw is NOT removed, and is still in the same place, its the one you wrap the o-ring around.

  • crazycarl7

Posted March 10, 2008 - 06:46 PM

#19

i have a 2005 yz 250f. So, if I do the oring mod, I dont necessarily have to mess with my leak jet? or do I need to change. Also, my stock pilot jet isa 42, should I go to 45?




 
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