Just bit the bullet on some "Bog" parts.


25 replies to this topic
  • William1

Posted May 18, 2009 - 12:08 PM

#21

+2 on David's comments. You want to always run the largest LJ you can without getting a bog. And before you ever try to fix a bog, get the rest of the basic jetting right and then.... leave it alone. Use the the AP to resolve the bog and the AP only.

  • ranger85

Posted May 18, 2009 - 07:33 PM

#22

I do use my eyeball to set the AP timing, but not by just looking at the squirt. I back the screw out to where I can see it leaving a wet spot on the slide, front and back of the slide, then I turn it in until it no longer leaves a wet spot on the slide, front, or back. I dry the slide off each time I check with a towel so I know when it's hitting the slide. I know I have it set perfect, and even after setting it perfect I have carefully twisted the timing screw every which direction at the smallest possible increments and gone for test rides and can't lick it. And this is 2 machines so I know its not something wrong with anything, and I can get rid of the bog by zip-tying the linkage.

I think a lot of people who think they have it set up perfect don't ride like I do however, if you are real aggressive with the throttle and really snap the crap out of it in lower rpms(And not saying you don't!), tell me you don't get a hesitation. If I snap it conservatively, there is no bog, or if I'm up in the RPM's some, there is no bog. Really the machines run awesome and are pretty responsive when you snap it conservatively. It's when you are being aggressive, like a 2-smoke, do you get these bogs. Most of the time I am conservative, its just when that pot hole, or stream, or log, or rock, or whatever comes out of nowhere, and you need to snap the throttle quick to loft the wheel up over whatever, and you were crusing along in lower rpms, that the bog occurs.

Every FCR equipped machine I've had, I've delt with this problem, and usually after tweaking the crap out of it, I get rid of it. The only machine I don't have this bog on is my Raptor 700, and of course its EFI, gosh you gotta love it!

I concur with the rivet length, and the swollen prostate squirt. While I am getting a pretty good squirt I think, it could be better. I'm going to test this new diaphragm with the shorter post once I receive it.

On my YFZ, actually my fiancee's YFZ, I've had the linkage zip-tyed for more than a year and no ill affects, and I couldn't get it to bog no matter what I did. I could lug the engine until it was about to cut off, and snap the gas as quick as I possibly can, and no hesitation what-so-ever. But, I just removed the zip-ty, and re-installed the O-ring, and the bog is back on that one.

Sooo, in conclusion, I think the "Red Beard" mod is actually the best way to get rid of this bog. I will know further after testing the Rapid Response linkage, and new diaphragm, but I expect positive results!

The 42 pilot jet does sound interesting, but according to my fuel screw, the 45 is just right, but it would be interesting to try. While the pilot jet does mostly deal with only idle, it does have an affect on the lower end, jussssst off idle throttle, and I think it's a lean bog anyway since zip-tying the linkage giving the maximum squirt seems to take care of it.

Hey thanks for sticking with me on this guys! You all have been a lot of help. I will keep tweaking till I get a positive result! :doh:

  • davidl9999

Posted May 18, 2009 - 07:38 PM

#23

Ok, I've set the AP timing that way too and it works; it's just a matter of really making the smallest change to barely miss the slide - which it sounds like you've done. :doh:

I don't know what else to suggest beyond changing the AP pressure spring and diaphragm. Maybe throw some money at it and put a R&D or Matrix AP on it, but it would suck if you did that and it didn't solve the bog. :snore:

Oh! I just thought of something...
On my 250, the o-ring mod didn't work with the first small o-ring I tried. I had to find another small, really thick one, and force that badboy over the cam and lever. It was tighter than a - well ykwim. :lol:
Anyway, the o-ring mod worked after that second o-ring went on. Seems like the AP needs all the pressure help it can get.

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  • ranger85

Posted May 18, 2009 - 07:48 PM

#24

Ok, I've set the AP timing that way too and it works; it's just a matter of really making the smallest change to barely miss the slide - which it sounds like you've done. :doh:

I don't know what else to suggest beyond changing the AP pressure spring and diaphragm. Maybe throw some money at it and put a R&D or Matrix AP on it, but it would suck if you did that and it didn't solve the bog. :snore:

Oh! I just thought of something...
On my 250, the o-ring mod didn't work with the first small o-ring I tried. I had to find another small, really thick one, and force that badboy over the cam and lever. It was tighter than a - well ykwim. :banana:
Anyway, the o-ring mod worked after that second o-ring went on. Seems like the AP needs all the pressure help it can get.



I did put the R&D Power Pump 2 AP cover on, with the heavier cam spring as well with no signifcant improvement, doh!:lol: Except that now zip-tying it with this set-up will almost completely cure the bog all throughout the range, where before it didn't, weird.

I agree with it needing more than just a stretchy o-ring, I've used the thickest ones that come with the JD jet kits with not much result. Securely fastening the linkage with a safety wire or zip-ty seems like the only way, but will put extra force on the diaphragm unless you get one with a shorter post which I have on order now. We'll see how it goes.

  • Charles De Mar

Posted May 22, 2009 - 09:52 AM

#25

I got rid of my bog by eliminating the JD needle and using a YZ450 needle. I tried every combination with the JD kit. My carb got a Quickshot 2, smaller leak jet, new main jet and YZ450 needle. The JD kit never worked for me. I tried it plenty of times.... I have no surge, no bog, and the bike starts on first or second kick.:doh:

  • ranger85

Posted May 22, 2009 - 10:05 AM

#26

I actually tried the Needle that comes with the GYTR kit, which I think is the YZ needle, and it made no affect on the bog. Funny thing though, I couldn't tell much if any difference performance wise between the JD Red needle and the YZ needle. I'm still waiting on the diaphragm to get here, which I think will solve the problem.

Thanks.




 
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