Carb jetting/tuning

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Dave Edwards

Guest
I recently put a Gnarly pipe on my 03 KTM 300 EXC.  The motor was kind of hesitant at first when opening it up off idle so I leaned it up a bit with the needle.  Now the throttle response is nice and crisp again at low rpm's, but the bottom end is still pretty soft compared to what I'm used to.  It seems like I need to wind it up more before it starts to pull real good. The midrange and top end still rip like usual, but with the stock pipe the bottom was nice and FAT.  That's what I want again -- do I need some different jetting?  Which way -- leaner(I think) or richer? My inclination is to go leaner with the pilot jet.  All hints/tips/suggestions appreciated!!
 
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Guest

Guest
You'll get nothing out of me until you FINISH BEHIND ME!

Great ride this weekend! And nice clean passing by my entire class... and I should know since I was passed by them all.
 
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Kevin Gent

Well-known member
I crushed the stock pipe on my KX 500 at Titusville. The Gnarly pipe I bought came with instructions for re-jetting. I followed them, it works great. Basically I went down 1 main jet size, 2 sizes on the slow jet, left the needle at stock. I looked at the FMF site, for some reason they don't have any recommendations for KTM, only Jap bikes.
 
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Guest

Guest
Dave:

Highly recommend going Leaner (lower number) on your Pilot (slow) jet.

Had to drop 2 sizes on my KDX220 when installing Gnarly pipe, and it was PERFECT!

Your problems are definitely in too rich a pilot jet.

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