New Keihin Jetting Guide for Novice to Pro

James Dean

Member
May 17, 2000
137
0
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Take 30 years of dirt biking experience and a mechanical engineering degree and put them together. Then ask if there is a better way to understand and make jetting changes on dirt bikes.
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See: www.JDJetting.com
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This Keihin jetting guide is now available to everyone and is unlike any before.

The Excel spreadsheet uses tables within the program to graph the needle profile (diameter) at the nozzle and show the relative change in jet orifice area from one setup to another.

The relative change in jetting is shown versus throttle position for all of these components:

-Pilot jet
-Needle diameter
-Clip position
-L1 dimension
-Taper
-Main jet

Additional correction factors are included to adjust for:

-Altitude
-Temperature

All of the components along with altitude and temperature are combined into a single "Relative Change" graph. The spreadsheet takes into account overlapping circuits and the transition between the needle and main jet mathematically.

All of the 2002 250 MX carb needles have been measured and tabulated in the spreadsheet: NOZE, N3WE, N8RH, N3EJ, NAFF, and the R11xxx, R13xxx, R14xxx needles.

There are over 200 Keihin replacement needles available between the FCR and PWK/PWM/PJ carburetors.These are all coded into the program. Also, a refined list of the most useful ones for ease of selection showing rich versus lean choices. With all the possible clip positions, pilot, and main jet combinations, literally thousands of settings can be evaluated.

If you ever want to do jetting, you need to see this first. The methods have been around for at least 20 years, but nobody has ever tried quantify and share them before. :eek:

James Dean
 
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KiwiBird

LIFETIME SPONSOR
Jan 30, 2000
2,386
0
I've got it and it kicks butt. When you have to remove the shock to remove the slide it's nice to know where to put the clip on the needle you are experimenting with.

This spreadsheet is very easy to use and understand. Money well spent in my opinion.

I'm hoping the next addition is to incorporate the slide cutaway in to the equation.
 

Farmer John

T.C.F.<br>(tire changin' fool)
LIFETIME SPONSOR
Mar 8, 2000
1,993
7
Originally posted by Kiwi Bird
This spreadsheet is very easy to use and understand. Money well spent in my opinion.

Understatement! :)

Even I can understand what is going on.
 

marcusgunby

LIFETIME SPONSOR
Jan 9, 2000
6,450
2
JD its no good you getting everyones bike on the planet jetted to perfection then trying to sell the method-you have done yourself out of a job:confused:
 

James Dean

Member
May 17, 2000
137
0
Well Put Marcus,

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But it's a job that I won't be missing!!:)


02YZ125,
A Mikuni version is desperately needed too. The needle codes in Mikuni are not easily identified. Nearly all are multi-taper and most will need to be purchased individually to identify taper position. It will be expensive, but would help many. Depends on the success of the Keihin version.
 
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James Dean

Member
May 17, 2000
137
0
Keihin Carb Models-

ZOOK250,

Yes, the spreadsheet will cover Keihin models back to the 1980's.
PJ, PWK, PWM, PE carbs use the same needles and codes.

02yz125,

We need to talk about options via email, not here.

James
 
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ZOOK250

Member
Oct 5, 2001
270
0
perfect jetting

got my copy of jd jetting and i have to say it does what it says.very easy to use ,once yu get the hang of it . took me a couple of hours , [playing around to figure out best combo's for my bike. the most important part of the program is getting a good jetting combo to use as a baseline to compare to. if you use a baseline that is to rich to begin with then the program will tell you how a different combo will compare relative to your baseline combo. some brain work is still required to get your baseline. on a day that your bike runs flawlesly , remember your jetting and with this program you can achieve the desired jetting for any temp or elevation anywhere, even if your bike is ported ,piped etc. definetly worth the money.definetly a good tool for tuning.
 

magra

Member
May 19, 2008
3
0
Dear Jams

it is possible to have a convertion table for needle?

i had some needle for Kehin PWK with this codes

N0ZF

N1ED
ecc

and I never find reference with official Kehin or Kehin-OEM R..etc etc. codes

Thank's in advance for Your answer (Edoardo - Italy)
 
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