low end bog 2008 yz 450f

11 replies to this topic
  • lanny574

Posted April 28, 2011 - 11:48 AM


I have been practicing at this track and there is a table to table into a triple and when I land off the second table and crack the throttle real hard in mid air close to the landing ramp to seat bounce over the triple it bogs real hard and I case it everytime. I have been playing around with the jets but nothing seems to be working. Would this have anything to do with the leak jet?

  • Octanee

Posted April 28, 2011 - 08:26 PM


i personally would say, maybe you should clean your carbs out totaly?, maybe somethings plugged in that carb? i would check up on that, as far as low end bog, thats odd and im thinking a dirty carb will do that,

  • Yamiryder

Posted April 29, 2011 - 06:41 AM


I'm not an expert but the o-ring mod might help as well as a boyeson quick shot

  • rcdude33

Posted April 29, 2011 - 08:41 AM


+1 on the oring mod!!

I did it to my 09 yz450f and boy did it make a difference. The bog is still there but it's 10 times better than it was. Also make get it rejetted to.

  • grayracer513

Posted April 29, 2011 - 09:09 AM


The quickshot is just so much bait to catch your money.

The O-ring mod is effective but the heavier linkage spring from Merge Racing is a much more workmanlike and permanent way to do exactly the same thing. The O-ring will eventually dry up, crack, and fall off.

Always remember that there is virtually no way to have your bike capable of tolerating an instant idle to WOT snap of the throttle without it adversely affecting other facets of the engine's performance, and it shouldn't be expected to accomplish that without EFI (if then). Riders need to learn to "roll" the throttle open a bit more gracefully. Not really slower, just smoother. Still, if the engine won't respond reasonably well, it needs some improvement.

  • Yamiryder

Posted April 29, 2011 - 03:46 PM


Gray, i've heard the quickshot helps but i've never actually installed one on my personal bike. So it's not worth the money?

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  • rcdude33

Posted April 29, 2011 - 04:02 PM


I really think the quick shot isnt even worth getting. Get your carb jetted and get that stiff AP spring or do the oring mod and ride:ride:

  • grayracer513

Posted April 29, 2011 - 07:26 PM


The only time a quick shot will make any improvement is if the OEM check valves in the pump cover are leaking, or seating inconsistently. Otherwise, it's not really much different than the stock part it replaces.

  • 2smokeforlife

Posted April 29, 2011 - 07:41 PM


The only time a quick shot will make any improvement is if the OEM check valves in the pump cover are leaking, or seating inconsistently. Otherwise, it's not really much different than the stock part it replaces.

Yep QS, QS2, and QS3 all they are is carb bling thats about it for the same price it cost you can buy every jet known to man. spend some time and just get it jetted correctly.

  • lanny574

Posted April 30, 2011 - 03:47 AM


What I don't understand is i have been riding this bike for two years now and it just started doing it. I installed a fmf slip on muffler, went one up on pilot and one up on main jet. I mean don't get me wrong the bike rocks, I rarely ride the bike from close to 1/4 so the big is notvthat big of deal, but I'm screwed if I have to seat bounce something out of a corner or on a rhythm section.

  • Diode663

Posted April 30, 2011 - 05:28 AM


I have an 07 and had similar problems. I wouldnt whack the throttle but at slow speeds it was a bear to ride and had nothing in the bottom end. I ordered a james dean jet kit and it solved those problems pretty awesomely. Really woke the whole bike up. I imagine though that the low end was fixed because of the o ring mod.

  • YamaLink

Posted April 30, 2011 - 05:35 AM


For sure, that JD kit is the "magical" fix for so many brands of bikes. I've seen riders tinker and mess with their jetting for an eternity, and come close (or for some get even worse, ha), but when they finally listened and ordered the JD life became a whole lot easier!

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