JD Jetting kit/guide vs factory KTM jetting specs


3 replies to this topic
  • singletrackfiend

Posted March 02, 2012 - 06:59 PM

#1

I apologize if this topic has been hammered into the ground in the past but it is new to me. My understanding of the JD kit is that it provides you with all the jets & needles etc that you need to jett your bike properly but is the performance difference with this kit really worth the money? I Have an 08 KTM 300xc with factory cylinder/piston and FMF/KTM exhaust and have been pretty happy for the most part with the jetting specifications given in the manual. Of course I'd throw down the money if the JD kit provided me with better performance but I just wonder if it is possible to achieve the same performance without spending all the $$$. Any input and experience on the subject would be greatly appreciated. Thanks!!

  • Kah Ran Nee

Posted March 02, 2012 - 07:26 PM

#2

I apologize if this topic has been hammered into the ground in the past but it is new to me. My understanding of the JD kit is that it provides you with all the jets & needles etc that you need to jett your bike properly but is the performance difference with this kit really worth the money? I Have an 08 KTM 300xc with factory cylinder/piston and FMF/KTM exhaust and have been pretty happy for the most part with the jetting specifications given in the manual. Of course I'd throw down the money if the JD kit provided me with better performance but I just wonder if it is possible to achieve the same performance without spending all the $$$. Any input and experience on the subject would be greatly appreciated. Thanks!!


The JD kit provides you with JD's specially tapered needles and main jets for multiple tuning and altitude scenarios.
It comes with basic instructions to get you on the right track.
For fine tuning, you still need a great deal of experience, or a AF meter and lots of time.

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  • singletrackfiend

Posted March 02, 2012 - 08:34 PM

#3

The JD kit provides you with JD's specially tapered needles and main jets for multiple tuning and altitude scenarios. It comes with basic instructions to get you on the right track. For fine tuning, you still need a great deal of experience, or a AF meter and lots of time.


I know what the JD kit is. What I'd like to know is whether it provides superior performance over a properly jetted bike with oem needles & jetts. Obviously there are those who have invested the money in it and will swear by it in order to justify spending the money on it. The KTM manual gives a good detailed chart as a starting point with jetting that seems to work well for me. How many of you have honestly noticed a major improvement in power delivery as a result of using the JD kit? Does it perform equally well on a 2 stroke as it does on a 4 stroke?

  • D0T-C0M

Posted March 03, 2012 - 07:41 AM

#4

If your fuel/air ratio is bang on the JD jetting will not make it better IMO. Factory jetting is usually on the rich side and linearity might be off versus throttle position. They slap on a defaut set of jets and needles at the factory but much can be improved when you dial it in by hand using a wideband o2 sensor. So bottom line if you properly tune your carb using OEM jetting than you'd be just as well off. JD jetting just get you there faster without much less trial and error.

Edited by D0T-C0M, March 03, 2012 - 07:42 AM.





 
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