2023 YZ125 - Jetting Fix

I’m going to quit over thinking it and just go with a needle with a bigger straight section if the burble is a problem. I would say if the stock jetting burble bugs you then the Y4 and 2026 getting is going to seem better but I think the lean pilot and straight portion hurt torque out of the hole. And then the richer power jet and main effect rev quickness and over-rev.

Will see I guess ?

Honestly I just want something I’m happy with in 90% of the riding I do. The OEM jetting really only shows it flaws (burble)in practice /hardpack situations where I coast off throttle(downhill. Sweepers mostly) otherwise in race situations I never notice it ( to busy concentrating on other things)

HFS

Have a buddy with the GYTR setup (68p/70pj/y4-3rd/165m)in his bike and he rode mine with oem(72p/35pj/NYDF -1/165m) noticed the slight burble but commented roll on from closed throttle significantly better quicker response -rest same ish.

He’s thinking of trying a 70p. Then maybe see if the 70pj is really necessary and go back to the 35pj.

We are confused if it’s the richer pilot( I do find a rich pilot feels better then lean) or too rich on power jet?

 

What elevation and temperatures did you test this jetting at?

Interesting they have superseded the older airscrew for the 22-25 models (4SR-14105-00-00). Now you can only purchase the airscrew from the gytr kit which is the same as 26 model noted by Rocket (4SR-14105-01-00).

About 800ft  around 65-70 degrees. I'm going  to try a 70 pilot with stock air screw. It seems like it wants a little more fuel down low.

Rode my 2022 yz 125 with the jd jetting red needle specs for 3000 to 6000 feet.

50 pilot

Red needle 3rd clip

168 Main

Stock powerjet

0.5 turns out from fully closed airscrew

Super strong rollon and low to mid response.

Seemed like a Richer Main could help as it felt weak on top.

Will also try a 52 pilot since i was riding at 6000 feet and i don't feel there will be margin to adjust once i go riding at 4500 feet.

Has anybody tried a 52 pilot with the jd jetting red needle?

I have 2200f 52p for the most part it gets rid of the quick throttle bog.

2200ft elevation 20c (70f)

thanks i will try the 52 pilot and after i test the 52 pilot maybe go to a 170 main.

Did a little testing with the Y4 setup this past weekend. Started off with 70pilot, Y4 clip 3, 168m, 70pj, and gytr a/s. Running straight T2 @ 500ft - 60° F. Definitely rich down low off the pilot circuit for me. I was getting a really bad lean surge around 1/2 throttle so I adjusted clip to position 4. Dropped pilot down to a 68 still seems a hair rich. Going to do more testing later this week likely dropping the pilot to a 65.

The initial roll on has been my main issue jetting the bike it’s been tricky to get right. I feel like diggers setup was the best the bike has ran. All circuits transition well and pull hard.

So I have tried many jetting specs including jd jetting and others. I have finally been able to get a hold of a CCL needle from diggers jetting spec. I’m am basically at sea level in southern new jersey , ran a 180 main jet, 55 pilot at about 1.75 turns out on air screw , and CCL needle on third clip position with a 5.5 slide at 32:1 klotz on 94 on a fresh top end  at 40 degrees Fahrenheit with a apex mx head and I cannot stress enough this is hands down the best jetting for this bike possible. I have tried everything, I have at least 10 main jets, 10 pilot jets and at least 15 needles, tried every combination including the Y4 needle and the 2026 jetting specs and this thing runs flawlessly. No bog, real 125 power. highly recommend hands down. I’m not sure what it will change to in warmer weather but this is the best jetting I have used so far. Just an fwi it ran this way on a moto track, the bike I have is a 2024 125, not an X model. I do not ride trail or anything so I do not know how it will perform outside of mx.

I Will try a 52 pilot with the jd jetting red needle 3rd clip and 168 Main for 1500 meters and 18 deegrees celcius. With the cooler temps the airscrew is only half a turn out

Tried the 52 pilot air screw at 1 1/2 turns out gained roll on power and got rid of the bog.

This bike is running great!

Did you keep the stock powerjet?

Revisited pro circuits settings for pump gas. I’d say it’s a fairly close baseline to start. It was around 60-70° for me outside. Pilot is spot on, found myself jumping between clip position from 3-4. Bike seemed slightly lean up top. I was going to test a 168 main until it snapped off in the carb. There did seem to be a very fine window of adjustment on the airscrew. I was using the newer airscrew which comes in the y4 kit which has a steeper taper.

Switched back to the old digger ccl setup (55p, 6.0 slide, 182 main, ccl-3, a/s 1.25-1.5 out (60-70°).That single taper needle works so well and is much easier to dial in. I do have a slight hesitation when I chop the throttle at lower speed in 2nd gear. This isn’t really an issue when riding on the track.

Is it worth going to the 5.5 slide at all?

I’m going to get the updated parts from the 26 and test them out. Never really liked the airboot on the 22-25s. Curious to see if the 26 is much different.

This is the 26 air boot. Shape seems roughly the same as the prior models. Only real difference I’ve noticed was the removal of the shroud at the 6 o’clock position. The opening at the 4 o’clock I believe is new as well. I’m still waiting to get my hands on the 26 airbox to see what is different.

Not sure if anyone has noticed, but the airboot on the 22-25s is the same as the 21 equipped Mikuni model (1C3 part no).