needle and clip position?


10 replies to this topic
  • blaise22

Posted August 05, 2008 - 07:23 AM

#1

I am trying to properly jet my bike right now but I dont really understand what the needle and clip position effect, Can someone please explain to me what richening/leaning out the needle will effect? and what is the difference between the red and the blue jd needles?

  • Vetmxrider

Posted August 05, 2008 - 08:22 PM

#2

Blaise22,
Changing the clip position on the needle will have the greatest effect on ¼-3/4 throttle openings. Moving the clip up towards the top will give you a leaner setting. I think the easiest way to understand how jetting needs to be adjusted for different temperatures and elevations is with a visual aid. Here is a jetting chart that I made/posted for another member a few days ago. This is specifically for the 2006 YZ250F. This should give you a good place to start. :)
Posted Image

  • blaise22

Posted August 07, 2008 - 05:59 AM

#3

wow that is amazing, thank you that really helped me out:thumbsup:

  • blaise22

Posted August 08, 2008 - 05:37 AM

#4

I race at a track thats always in the 75-95 range, do you think it would be best to use the JD red needle?

  • Vetmxrider

Posted August 08, 2008 - 06:59 PM

#5

What track to you race at? Are you in Southern or Northern Cal? Elevation? As far as the JD needles go, if you already have them I would give it a try. I purchased a set of JD needles several years ago for my 02 YZ426 and was very pleased with the results. The last few years I have just been using my jetting program with parts from where I work or any of my local dealers. As posted on the chart (in red), I would also recommend that you try replacing the stock #80 Leak jet with a #60.

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  • blaise22

Posted August 09, 2008 - 10:59 PM

#6

What track to you race at? Are you in Southern or Northern Cal? Elevation? As far as the JD needles go, if you already have them I would give it a try. I purchased a set of JD needles several years ago for my 02 YZ426 and was very pleased with the results. The last few years I have just been using my jetting program with parts from where I work or any of my local dealers. As posted on the chart (in red), I would also recommend that you try replacing the stock #80 Leak jet with a #60.


I race at starwest in Southern California, the elevation is 1457. Im going to try out the red neddle with your exact settings, they seem to match up perfectly with my elevation/temp. the biggest leak jet I have right now is a 50 so im going to put that in for now and switch it out with the 60 when I get it.
Thanks for all the help: up:




Before I had:
main:180
Needle/clip position:JD blue needle/5th clip position
pilot:45
leak jet:40

Current jetting:
main:180
needle/ clip position:JD red needle/3rd clip position
pilot:42
leak jet:50

  • blaise22

Posted August 10, 2008 - 09:39 AM

#7

It fires up on the first kick every time and idles fine but I cant adjust the fuel screw rich enough should I put the 45 pilot jet back in or what?

  • Vetmxrider

Posted August 10, 2008 - 04:43 PM

#8

How far out (numbers of turns) did you try adjusting the fuel screw?

  • blaise22

Posted August 10, 2008 - 05:38 PM

#9

I adjusted the fuel screw 3 turns out and it still was very lean so I switched the 42 pilot jet out with the 45 and it is perfect. I havent rode it yet with the new jetting but just letting it idle and bliping the throttle there was a huge difference, it feels so crisp with no bog or backfiring I cant wait to try it out at the track:thumbsup:

  • Dave Hopkins

Posted August 11, 2008 - 09:17 AM

#10

As far as the difference between red & blue goes, red is leaner from idle to 1/4 throttle, after that they are the same

  • Thrash1

Posted December 12, 2008 - 09:31 AM

#11

I was wondering, I have the same chart in Excel and was trying to figure out how do you use this chart to predict the jetting settings. If you adjust the Red numbers. The numbers on the chart change to predict different jetting settings. Maybe I need to purchase a Jet Kit and then everything will make sense.

I have a '01YZ426 that just rips, I haven't changed the jetting since I purchased the bike some 3 years ago. I wanted to verify everyone is correct on the jetting side and have been doing the research to see what I need to check and so on.

I have modified the pipe a little(Because I flipped it practicing starts.LOL) and cut about 3" off of it. I repacked it and everything looks great its just a little bit louder :thumbsup: . I'm also running an 07 air box which directs air straight into the carburetor. Full FMF Power Bomb header and FMF Ti4 exhaust.

I've riddent the current Jetting from 30ish to 100+ degree days? I'm just wondering If I should even mess with it?




 
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