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Here is a video I made with my experience jetting this bike. Digger’s jetting specs and Pro Circuit jetting specs
YouTube link. https://youtu.be/TDFGvutDjwo
The bike is super responsive at any throttle position. Best running 125 I have ever tried. Don’t forget to get the stationary cable holder with the CCL needle.
Digger Jetting:
Throttle Valve(slide) 6.0 7.0 is stock(6.5 X model)
Jet Needle CCL
Clip 3 2(high elevation/warm)
Power Jet 35 Stock
Pilot 52 50-55
Air Screw 1-1.5 turns out
Main jet 182 178-185
Throttle Valve stamped 6 for Keihin PWK38S
Keihin Part #: 018-521 N502-17E01
022-040 N502-27600 Notched
99’-00’ Kawasaki KX125 Part #: 16025-1215
KTM Part# 54631235006
JD Jetting Part#: JDKH11
CCL Needle
Keihin Part#: N427-48CCL 017-464
1988 Kawasaki KDX200 Part#: 16009-1387 R1370E
Cable Holder
Kawasaki Part#: 13169-1063
JD Jetting Part #: JDKH16
—————————————————————————————————
Pro Circuit Jetting:
See Pro Circuit jetting specs on their website
Only recommended change
Clip position 4 On the needle jet
Will need:
GYTR Jetting Kit YZ125 22’-24’(Y4 Needle)
B4X-CARBS-KT-10
or
Y3 Needle
Keihin Part#: N427-11Y03 017-138
S there a performance gain to be had. If My bike doesnt bog and doesnt spooge with the current jetting using the provided Jets and needles?
Would doing these jetting mods gain front end on the dyno?
Nice video.
I wish you had turned the slides around and pointed out the difference between the 2 slides. The OEM spec'd Yamaha slide has an S or an R stamped into the TPS pad at the top of the slide, while most other slides (non Yamaha spec) do NOT have anything stamped into that pad. You can use both style ( spring loaded and non spring cable holder) in the Yamaha Spec slide, But you can ONLY use the non spring loaded cable holder in all other slides. Do not remove the spring from the Yamaha holder and attempt to use it in a Non Yamaha slide. Using the brass Keihin needles (CCx) you can probably get away with using the spring loaded holder in a non stamped slide for a little while, but I wouldn't do it for long. When using an aluminum oem style needle, it will break with in a matter of a couple hrs.
I updated the video regarding the cable holder.
Thanks Digger
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Thanks for making this video and going through the details. I'd love to see some footage of this bike ripping around a track with that jetting.
Before ordering the #6 slide and all the parts, I decided to try one thing that dumb me didn’t try a while ago. JD jetting spec with 40:1.
the bike runs mint now, the lean bog is gone I feel like maybe JD should have specified this in their manual because even the JD tech said that the kit is supposed to be ran 40:1 instead of the manual spec 32:1.
anyway thanks for the help everyone!
Well i decided i Will go for the y3 needle and pro circuit Specs.
I Will fiddle with that starting point having in mind i'm in México at 5000 feet and 90 deegres Fahrenheit with Valero mexican fuel
Hey Digger, did you test that YZ with notched slides? The Keihin-FCR store guy told me a notched 6.0 is close to a regular 6.5.
I ordered the #6 with no notch to use with a CCL needle.
Not true, the notch makes the pilot circuit a little more efficient, which in turn sometimes requires a leaner pilot, on some bikes. The notch also helps the bike idle a little better. I go back and forth between notch and unnotched slides all the time.
Thanks for the clarification on that. I'm looking forward to trying your setting with the #6 slide.
was excited because i thought i could buy a y3 needle online. turns out the site was incorrect and they didnt have it.
is anybody thinking about reselling their leftover jet stash after getting your jetting dialed?
Partzilla has the Y4 needle available which replaced the Y3.
https://www.partzilla.com/product/yamaha/B4X-CARBS-KT-10
Thanks!
Just found on YouTube,
Yamaha YZ125 Jetting + 30 Pro Setup Tips
https://www.youtube.com/watch?v=DZtSpPDD3O4
Just got the JD kit delivered and it does specify 40:1 mix with 91-93 ethanol pump gas for the jetting. Maybe the older kits did not have this in the instructions?
Was able to get a 6.0 slide from Keihin FCR. Found the CCL needle on a cart racing website should be here tomorrow. After how bad the stock jetting is I don't feel like even wasting my time trying to run it.
Seems crazy they let the bikes out with this bad jetting from factory. My older yz with a mikuni runs a 5.0 slide. Shocked to find out this has a 7.0 stock.
Going to try the JD jetting out first then roll with diggers specs once I get the last few jets I need. Appreciate Bmograt making a video and digger sharing his knowledge.
Tested out the JD jetting kit today and wow this has to be one of the best jetted bikes I've ever had. Idles like a dream without loading up and pulls nicely all the way to the top without any issues. Not quite sure what fuel is in my bike from dealer looks like T2 VP.
Blue needle clip 3, 172 main, A/S 1.5 turns, 50 pilot (85-95 degrees 500ft)
For which temp and elevation is this jetting?
My 24 YZ125 has about 10 hours on it and even after jetting it to FMF's specs, it can probably go a tad leaner. At first the bike was spewing unburnt oil everywhere but the jetting seemed to clean that up a little bit. On the days I ride, it runs like a champ, but when I'm getting back on the track after a water break, it will bog and I have to blast it out again, then its good to go. It still spews a decent amount of oil from the pipe/silencer connection even on days I hold it wide open, but not quite as bad as when it was at the stock jetting. I ride Florida/Alabama year-round with Blud synthetic premix, 30:1, fires on first kick, never fouled a single plug.
Jetting now:
Main 162
Pilot 72
Needle NYDF
Clip Position 1
Air Screw 3.5
Pit Row
wild a 62 pilot is sooooo fat, glad u got it sorted. not many things in this world like a crispy 125.
I just dialed the jetting in on my cr125 w/ 38mm PWK airstryker Longbody.
JD needle
45 pilot
185 main
Form what I gather, a rich pwr jet will soften the lower mid thru upper mid. Leaner is meaner...until it's not.
BTW, JD is helpful to many and generally good, but its target is just that. It doesn't nail the hottest tune. Just sayin'
22-24 yz125 can be made to run flawlessly with the following spec. summer- Needle NYDH clip 3, pilot 52, main 175. Winter- Needle NYCH clip 2 or 3, pilot 55, main 178. These consistently outperform JD kits on the track based on rider feed back. The Y4 needle is supposed to be good but is almost impossible to get a hold of, the NYDH needle can be tough to find sometimes as well. If you cant find the NYDH, the NYCH works just fine in the summer on clip 2. This is 40 bucks worth of jets and 98% of the people riding this bike would call it perfect with minimal effort. No loading up, no fouling plugs, steadily consistent idle. Videos for any one that is curious to see our bikes run. These specs are based on sea level location, with a 32:1 mixture of Amsoil Dominator and 93 octane standard pump fuel. Spark plug is BR9EIX. Jetting works well on both a stock pipe/PC shorty combo as well as an FMF/FMF Shorty Combo. I have tested these settings extensively with both a twin air filter, and Maxima ProFilter disposable air filter. Great results both ways
Starting diameter of popular needles listed below. Sharing this info because I think this is a large part of the problem most are experiencing with the new model YZ’s. Most of the popular jetting specs try to run a very small pilot jet to mask the root cause which is an overly rich starting diameter on the needle.
JD Blue .1055”
NYDE .1055”
NYCF .1060”
JD Red .1065”
NYCH .1065”
N3EW .1070”
Y3 .1080”
Y4 .1085”
Looking at this data I can see why the Y4 needle would use the larger pilot jet when compared to the Y3.
In my experience with these bikes, I would always try to use the largest starting diameter needle you could find and use a bigger pilot jet to avoid the lean bog condition that many experience (when using the stock #6.5 or #7 slide).
I tried sourcing the #6 slide and CCL needle that Digger recommends but that proved to be a tough task.
Yamaha's YZ125 OEM jetting in the Keihin, is clearly an end around the lean slide. Once you install the richer slide, it really opens up your jetting options. FWW, I didn't like the OEM NYxx or the N3xx, both dual taper, series needles, when using the stock slide, over a wide range of temps. If you got just a little bit under the temp range on those needles, with the stock slide, that lowend bog came back. If I owned one, I would purchase a 5.5 slide, under the KTM part#, and I would cut it to 5.75 and start with and H or W starting diameter needle, dual or triple taper needle. The std 5.5 slide work very good as well, and I wouldn't be afraid to use a single taper CCM needle with it either, which is still available, I believe. This will give you a bunch more options, needle wise, instead of relying on one needle to work year round.
You can't base all your evaluations on the starting diameter and pilot size correlation. You have to take into account the needles tapers. single, dual, or triple.
I can do the conversions, but it just looks odd to me seeing the starting diameters in inches. 2.725mm = an H starting diameter, 2.735= W. The CCL single taper needle, that I recommend has a starting diameter of 2.705.
My 2024 YZ125X Jetting Spec is posted below. If you are having trouble getting your 125X dialed in, this may help you get it to an acceptable tune. ***NOTE*** My 2023 YZ125 jetted completely different than this 2024 YZ125X model.
2024 YZ125X Jetting Spec:
JD Red Needle in 4th clip
185 main
60 Pilot
2 out on AS
75 degrees
Sea Level
100% Avgas with 32-1 Bel Ray H1R
Apex SX/XC Dome (std compression)
It’s not 100% perfect but it feels really good on the stand and riding through the subdivision. I will test it in race conditions this Sunday.
Over the last several days I tried the Y3, Y4, NYCH, JD Blue, and the JD Red needles. With each of these needles I tried several different mains, pilots, and clip positions to try and get an acceptable tune. The JD Red was definitely the standout and had the least amount of drawbacks. Once I figured it was the best for my situation I made several adjustments to nail down what I thought was the best setting using that needle. Hopefully the above setting helps someone.
6.5 slide?
Yes, the 6.5 slide that comes stock in the 125 ”X” model.
If you purchase an aftermarket Keihin PWK AG (Air Guide, the shorty model most people use) they come with a 6.5 slide. So it's a pretty readily available slide.
I was able to test these settings today in a Cross Country race. There was single track, fast fire roads, hill climbs, and everything in between. A really good test on virtually all conditions. The engine ran amazing! Not one time did it bog, load up, hiccup, fart, etc, it just flat out performed!
One thing I didn’t mention in my original post about this jetting spec is that this setting has considerably more torque than the other jetting specs I tested. It works really, really well on my 125 “X” model.
This is basically JD Jettings “trail spec” with a 60 pilot instead of the recommended 50 pilot. If you are struggling to find a good tune on your “X” model give this a try.
Hey man I just ordered the #6 slide and nozi with a 178/180 main and 45/48/50 Pilot. I am at 8,000ft would you say go to clip #2 or #1 or something else?
And I have an apex sx/xc dome if that would affect what you would say.
At 8000’ and using that NOZI needle, you’re going to be quite a bit leaner than when using a single needle. I would start out with the needle in clip #3, along with a 45 pilot, and it may very well need to be leaner. The main is going to be pretty lean as well. I would start off at 175, but again, it may need to be leaner.
FWW, I would have use a CCM needle, 50,178 combo , and went from there.
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