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03 WR450 Jetting and low end performance

By Thesykboy,
in WR400F/426F/450F

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Grand Master

FORMA MOTO

Posted
Posted
You know Max, I can't tell you how many times I've caught that little plastic nut out of place after wondering why it's still running lean! I have it taken care of now...

So I think I have this baby licked! After hearing it pop and stutter with a #45 pilot and seeing it run GREAT with a #50 (but while being able to bottom out the mix screw with no idle change), I settled on a #48. And my needle clip is on the 3rd place setting FWIW.

It runs smooth on the #48, but if I bottom out the mixture, it doesn't die. It runs REALLY rough and sounds like it could eventually die, but it continues to run. I got the screw out to 1 1/2 turns to have a smooth idle, but I still wanted to check and inquire as to if where I'm at sounds about right. Since it took almost exactly 3 turns out to get the idle smooth (still backfired though) on the #45, I figured the #48 HAD to be the trick.

How'd I do?

You win a Blue and White Cigar. :busted:

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  • 1 year later...
Grand Master

FORMA MOTO

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Hi, could you please explain what is meant with "stickys" or provide a link to them... 

I am about to disassemble and clean a FCR -39H Carb and might need to read these...

Many thanks!

They used to be called 'stickies', and now they are labeled as 'pinned' posts, at the top of this forum. 

A good two days worth of reading....

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Arjan van Druten

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They used to be called 'stickies', and now they are labeled as 'pinned' posts, at the top of this forum. 

A good two days worth of reading....

Thanks Krannie. I found the "Pinned"Posts. There are about 10 of them at the Wr/400/426/450 I noticed. Is it about all of these, or also others in other Maps?

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  • 4 weeks later...
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gilbertron7k

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I have a 03 wr450 dynatec cdi fmf powerbomb header dg muffler and open air box bike sputters horribly at a at steady rpms and backfires like a machine gun on decel got it back this way from the shop and they claim its not a jetting issue after rebuilding and rejetting my carb what jets should I get and do it myself

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Grand Master

FORMA MOTO

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Pull the pilot jet, clear the passage above the pilot jet with monofiliment (big fishing line) and spray brake cleaner.

Upon decel, the only part of the carb that is active is the pilot circuit, so that has to be it, or, you have a MASSIVE air leak in the pipe at the header crush washer, or fuel screw (missing oring), which also needs to be adjusted per the pinned post at the top of the forum ('pilot setting')

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gilbertron7k

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The new header came with anouther crush washer and she's really running better but still not that smooth at a steady rpm I know a lot of wrs do this but that's why I got the aftermarket cdi that said it got rid of that and its still there I also had the carb rebuilt and jetted but could it still need to be cleaned out better or is this stuttering not gunna go away?

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