Off Idle Bog On A WR450

6 replies to this topic
  • timvv51

Posted May 15, 2003 - 03:41 PM


Is the Sudco pilot air screw something that could help with the off idle bog. Or is the best cure for the off idle bog the BK mod. The bog is not bad, just could be better I think. There is also a tuning step in the manual about timing the slide so the squirt starts at the right time by inserting a round shaft (doesnt say what diameter)to hold up the slide and turning the screw inside the throtle cable cover so the timing is right. This step is a little vague in the manual. Has anyone had any luck getting rid of the bog with this step? I am just not thrilled about the idea of removing the carb and drilling holes in it (BK mod) to get rid of a slight bog. Seems like some have eliminated the bog without the BKmod. Bike really runs great except for the fourstroke bog. Tim

  • endurodog

Posted May 15, 2003 - 04:53 PM


I read in MXaction that the YZ450's need to have this screw turned in 1/2 turn so I did that on my WR. It seems to help but I still have a little bog there.

  • timvv51

Posted May 15, 2003 - 05:27 PM


Yeah Enduro Dog. I think I recall where you mentioned that in a post just recently. This screw can be adjusted while the engine is running and I messed with it (carefully counting turns) and after not seeing much difference retuned it to factory but I will follow your lead and turn it in a half turn and see what up. I would still like to know more about the Sudco screw or pilot air jet.Is it accesible with the carb on the bike. If I am looking at the manual right it is in the side of the carb next to the engine on the lower edge of the bell. If so changing or adjusting will neccesitate carb removale. Thats a chore on this bike. I'm new to pumper carbs. I have changed many pilot jets but never a pilot air jet. Off the top of my head I believe about 70 is stock and most people are changing to around a 100 air jet. And this could neccesitate changing pilot jets. Sorry for being vague but I am at work and dont have my manual in front of me. Tim

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  • SBG

Posted May 15, 2003 - 07:37 PM


I have the Wr250F, but I'll relay how I've fixed my bog. The PowerNow. I had a bad bog mixed with the cdi/miss problem with 03 250f's. Now I can't even feel the cdi miss because the power comes on so smoothly that it doesn't have a chance to hang up. Also look into the R&D P-38. It basically is a BK mod for $73 and those who have it say it's better than the PowerNow. It also makes your carb look cooler with red anodizing (if that means anything to you).

  • timvv51

Posted May 16, 2003 - 03:55 AM


Thanks for the info SBG. I did a search on the R&D P-38 and found one refrence to it but not much there. Could you elaborate. Most of the info was on the BKmod which I just need to find the time to do. But I would like to know more about the R&D P-38. Thanks Tim

  • SBG

Posted May 16, 2003 - 06:10 AM


Not much info out there, but this is from the R&D site: P-38

MXSouth has a better write up. MXSouth P-38

  • FNG241_WR450F

Posted May 16, 2003 - 06:14 AM


I had the same problem. I'm at sea level. There's a great article in the March addition of Motorcross Action mag that deals entirely with setting the fuel screws. I learned that 4 strokes don't have air screws, just fuel screw. They walk you step by step in adjusting the screw. I installed a fuel screw from zip-ty racing that makes it a lot easier to adjust. It's a little tougher on the wr than the yz b/c the starter stuff gets in the way. Read the article! After I did the adjustment, the bogging is gone.


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