KDX Jetting Database (complete)

A reference for the PWK carbs...
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Jaguar
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KDX Jetting Database (complete)

Post by Jaguar »

Every jetting database on forums I’ve seen so far lacked essential data such as weather data which can make a huge change in jetting needs. Also whether or not the gasoline has ethanol and at what percentage (it should be listed on a sticker on the gas pump). I consider every detail important because they all figure into the final mix. I just made a jetting calculator which shows a graph of the jetting all through the throttle settings. Too rich is above the 1.0 line, and too lean is below the 1.0 line. So I’d like to start a new database here for KDXes and after a handful are submitted I will post the calculators results for each data set, showing how rich/lean it is at half throttle and 7/8 throttle. I will make needle recommendations also. So here is the info needed. Please don’t submit unless all the info is filled in. thanks
engine cc:
carb size:
fuel/oil ratio:
% ethanol in gasoline:
standard or modified snorkel:
pilot jet:
needle ID:
clip position (1-5. 1 is at top):
main jet:
slide cutaway (I think 5mm on '95 and newer and 6mm on all others):
feet elevation above sea level:
% relative humidity:
fahrenheit temperature:
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: KDX Jetting Database (complete)

Post by Jaguar »

If your jetting best suits a certain type of weather then use those weather details.
How these details affect jetting:
Higher elevation, higher humidity and higher temperature all cause richer jetting (requiring you to install smaller jet sizes).
More ethanol causes leaner jetting (requiring larger jets)
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: KDX Jetting Database (complete)

Post by John_S »

Thank you for helping out with jetting. As my bike sits now

2002 220
RB head
35 air striker
Vforce reeds
FMF woods and Turbine Core 2
40:1 Honda HP2
1/3 110 octane, 2/3 90 octane recreation fuel (non ethanol), both Chevron
Air box lid and snorkel
40 pilot 1.5 turns out
JD red 2nd clip
145 main
4.5 slide
Sea level
77 degrees, 63% humidity

This set up is responsive and has very little spooge, none dripping but black and a little tacky inside the end of the silencer. Clip 3 or a 150 main would both sputter rich and drip spooge
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Re: KDX Jetting Database (complete)

Post by Jaguar »

here's info from JD Jetting:
The needles in the KDX jet kits are in the same range as CEK/DEK single taper needles, but ours are custom machined triple tapered needles. They are precision machined and give a more even flow of power than standard needles, but do not get excessively rich like N85D type needles. There are 2 needles in the kit, which span either side of CEK/DEK with slightly richer and slightly leaner straight diameters. The Blue marked needle is for lower elevations and cooler temperatures (richer), and the Red marked needle is leaner on the straight diameter for warmer conditions or slower paced riding, but not excessively. Yes, these are special needles, as I've spent years developing and refining the taper angles and lengths to make them perform in varied conditions without being as sensitive to changing weather and temperatures compared to stock needles. The needles will work well with the RB modified carburetors.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: KDX Jetting Database (complete)

Post by Jaguar »

these special needles don't have published dimensions so I can't analyze it on my calculator.
Normal PWK needles I can find their dimensions.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: KDX Jetting Database (complete)

Post by SS109 »

Someone with the JD needles should measure them on a good set of calipers and post up the specs.
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Re: KDX Jetting Database (complete)

Post by John_S »

Jaguar I've switched from the JD red to the CEL enough to know that all the settings I listed above would be the same if I used the CEL on clip 2 instead of the red needle on clip 2. Would you be able to work with that?

SS if I had a good set I would check but the ones I make due with are definitely not a high quality tool.
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Re: KDX Jetting Database (complete)

Post by Jaguar »

Probably not because having precise dimensions are important. The red needle is a triple taper which is very unusual. And the air striker has a different kind of slide. My calculator expects the slide to be somewhat normal.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: KDX Jetting Database (complete)

Post by Jaguar »

Here’s my new videos:
About 2 Stroke Jetting
Jetting Calculator Spreadsheet
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: KDX Jetting Database (complete)

Post by rungrandpa »

see below
Last edited by rungrandpa on 09:51 am Jan 30 2019, edited 1 time in total.
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Re: KDX Jetting Database (complete)

Post by rungrandpa »

UPDATED back to my old set up. Better top end and MPG
1990 Type E
engine cc: 200
carb size: PWK 35
fuel/oil ratio: 40/1 amsoil Interceptor
% ethanol in gasoline: 0%
standard or modified snorkel: No snorkel
pilot jet: 40
needle ID: BGP
clip position (1-5. 1 is at top): 3
main jet: 152
slide cutaway (I think 5mm on '95 and newer and 6mm on all others): stock 6mm
feet elevation above sea level: 2800
% relative humidity: 60
fahrenheit temperature: 47
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Re: KDX Jetting Database (complete)

Post by MoonStomper »

Jaguar wrote: 08:44 pm Jan 07 2019 If your jetting best suits a certain type of weather then use those weather details.
How these details affect jetting:
Higher elevation, higher humidity and higher temperature all cause richer jetting (requiring you to install smaller jet sizes).
More ethanol causes leaner jetting (requiring larger jets)
So with the above being true - could someone run ethanol gas in cold weather to counteract the richer jetting expected? Then in the warmer months return to non-ethanol and never touch your jets. That would be an interesting experiment.
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Re: KDX Jetting Database (complete)

Post by cbittner72 »

96 200cc
35mm original carb I believe
32:1 - have tried both klotz super techniplate and Motorex
93 octane with 10% ethanol
No snorkel lid on
35 pilot
DEL
Position 2
155 main
5 slide
Sea level basically
60-100%
60-100F

FMF Gnarly, stock muffler, Rad valve

I used the kyajet app which was very useful to understand how tweaking each variable would change fuel flow at each throttle position. Everyone says how rich the stock jetting is, but really with the DEL needle, I’m mostly richer everywhere except idle and 1/4 than stock. I think that 5 slide causes lots of problems at idle?
6A2D6520-3765-49B4-B27B-55960567CE7E.png
6A2D6520-3765-49B4-B27B-55960567CE7E.png (220.62 KiB) Viewed 5539 times
And here is how the prior owner had it jetted and how much richer I have it. It spooged like crazy when I got it, now with richer jetting, much less spooge.
BCDA4C33-0B7D-4333-8014-C47299332F1E.png
BCDA4C33-0B7D-4333-8014-C47299332F1E.png (248.29 KiB) Viewed 5538 times
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Re: KDX Jetting Database (complete)

Post by dillydalley »

2001 200
35mm Airstryker
60:1 motorex
Ethanol free 87
Snorkel removed
42
Stock 1174
clip position 2
152
slide cutaway 4.5
2000-3000ft
30-50°
Stock pipe and silencer

I chased the notorious blubbery carb problem from oem carb. Nothing fixed it. Bought a new genuine 35mm Airstryker from jets r us. Ordered the DEL needle with it because of all the good things I read about that needle. But it was still way rich so it must only work well in an RB modded carb. Went to the stock 1174 needle and now the bike runs super clean with the setup above. This coming from a tpi guy.
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