06YZ450F Bogging

14 replies to this topic
  • gerald28

Posted August 08, 2006 - 05:13 AM


Hey everyone,

I bought a 06YZ450F this past May and have loved it. 2 weeks after I purchaed it, once I broke it in, I had the shop rejet it (it was backfiring a lot). Since then, it ran great.

Two weeks ago, it started bogging at the first throttle crack. If I roll it on slowly it is ok, but if I turn it with any speed it bogs and/or dies. I thought I might have over oiled my air filter (but I have changed it twice since). Prior to 2 weeks ago, the same crack would not bog it. I have not changed settings or parts since then.

Any suggestions on where to look? I assume it is a jetting issue. What might cause it to change all of a sudden?

1) The bike is stock, with only a Boyseen water pump put on in June.
2) I ride MX and Enduro in Central/South Texas
3) It is hot and humid, but it is always that way down here:)


  • rcmxracing

Posted August 08, 2006 - 05:20 AM


Your fuel mixture screw didn't fall out did it?

  • gerald28

Posted August 08, 2006 - 05:23 AM


I couldn't imagine, but I am certainly going to check when I get home.


  • Ranger18

Posted August 08, 2006 - 06:09 AM


Your fuel mixture screw didn't fall out did it?

I was thinking the same thing.. If it isn't out, then it is probably close to falling out. You should replace it with a zip tie screw if you have the stock one in. Otherwise turn the screw in, then back it out about 2 turns and adjust from there.

  • jamiehughes

Posted August 08, 2006 - 07:45 PM


maybe, dirty air filter??? just a shot in the dark..

  • jwcrf05

Posted August 08, 2006 - 08:54 PM


the temp and humidity levels haven't changed have they? my bike ran great all spring then about halfway through the summer the thing bogs like crazy. a smaller pilot jet and one smaller on the main was the cure, we have been in a heat wave lately so temps are hotter and humidities are higher than normal, you might be able to dial it out with the pilot screw though. try a 165 main and a 45 pilot if thats not what you are already running.

  • Joe_Jet

Posted August 09, 2006 - 05:16 PM


Sounds like they jetted the pilot too rich.

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  • Troutman

Posted August 09, 2006 - 05:28 PM


Sounds like they jetted the pilot too rich.

I am thinking the same thing. If your bike doesn't pop at all, even a little bit, on decel it might be to rich. I would try turning your fuel screw in a 1/4 turn at a time and see if that helps. If it doesn't and if they put in a 48 or bigger pilot you might try a 45. Mine did the same thing in the woods and I adjusted the fuel screw and that cleared it up but it now pops very slightly on decel. If you are still running a stock fuel screw you also might want to get a Zipty or Stealth it will help with the fine tunning.

  • Budlite

Posted August 09, 2006 - 06:53 PM


If you've lost the fuel screw get the Zip-Ty with the knob on it, they make two versions. You'll also need the spring, washer and o-ring. Suzuki sells them individually. Honda, Yamaha, and Kaw sell them as a set. Big difference in price because they come with the screw itself. You might consider extras as they are hard to get in a hurry. Once installed, safety wire it so that if it comes loose again, it won't fall completely out.

  • redrider91

Posted August 09, 2006 - 07:09 PM


Our fuel screw fell out and we had this problem, so we bought an aftermarket one and turned it in all the way then 1 1/4 out and it runs great. I just have no clue how the stock one could fall out but w/e.

  • matt116

Posted August 09, 2006 - 07:13 PM


A little o-ring around the fuel screw will keep in place. see pic

  • gerald28

Posted August 09, 2006 - 09:13 PM


Ok, I checked it. It has not fallen out. Unfortunately, I was not smart enough to ask the dealer where they set it when it was rejetted...so I don't know if it has come loose at all.

I figure I will reset it to 1.5 to 2 turns out and go from there.

Thanks for the help everyone!

  • gerald28

Posted August 09, 2006 - 09:14 PM


Yea, I thought it might be that or that I over oiled the filter. So I have changed it twice over the past 10 days just to be sure.

  • gerald28

Posted August 09, 2006 - 09:16 PM


How many degrees will make a difference? I live in central texas, so it is HOT. But I had it jetted in late may or early june. So it is only a few degrees hotter now than early summer.

  • gerald28

Posted August 09, 2006 - 09:18 PM


Yea, it does not pop at all. Boy when it was new, before the rejet...it poped like a popcorn maker. But even now that it is bogging, no pops.

i will try turning in the screw to see how that helps.


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