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you could pick the 42 or 43 and start on middle clip then adjust.
FL average altitude is100 ft , TX where's AJ ~ 1700 ft and Colorado 6800 !
So pilot and main jet you'll have to test and tweak.
On my MC : AJ's specs (I got PV set differently but that's personal pref.)
MJ 490
PJ 32.5
AS ~ 1.5 turns out
Needle jet S4
Needle 42-75 on the 2nd clip
Slide 5.5
Fuel mix 50:1 non ethanol - Maxima K2
5.5 Slide
S-4 needle jet
42-75 jet needle
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I'm guessing I'll have to use quite smaller jets than the average person on here.
Currently installed
MJ - 430
PJ - 32.5
42-71 Needle
________________
It sounds like I with these mods I would increase my main jet. I'm surprised that you are running such a large PJ?
As for higher elevation levels I think there was a guy somewhere in this tread that is at 6500’ and he runs the 5.75 setup. I think he did have to back the main down to a 490, I can’t remember. In all honesty since jets are cheap you might want to get 470-500 and maybe a few pilot jets too. This jetting has been really stable at a huge mix of altitudes.
Also how are we able to run such larger main jets.
I'm not really a carb guy so just asking.
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
PJ- I currently have 30,32.5,35,37.5,40
Should be good to start.
Would you just suggest the new needle in the middle, MJ 470 and a 32.5 or 30 PJ?
MJ wise I’d get a 480, 490, and a 500. These bikes love fuel is how I’ve been getting away with it. Pilot jet wise you’re covered. I’ve only had the 32.5 and the 35 work for me and that when it’s hot or cold. You’re gonna have to play with the settings since you’re in thin air. Start with the specs for the 5.5 slide and see how it runs and we can go from there. Another wrench in the works is the spark arrestor, that’s going to make it run rich so know that going in. Maybe digger will see this and provide some insight about that part of it as I’ve personally never messed with one.
I live outside St.Louis Mo. , and the official height above sea level is 433 feet.
And second does this jetting setup make that much difference? I have only ridden the bike four times now, gently, wide open trails and fields, just breaking it in and not wanting to
"age" it too fast. I'm still on stock jetting and 110 race fuel mixed at 40:1.
Now that's it getting warm it's to rip! The carb does seem rich and I have more than normal spooge. I am more than willing to get the slide and nozzle if I'm sure its better.
P.S. I already have updated CDI. Thank you.
Any chance I could email ya? Love to have a yarn about a few things on the 250sx. Sounds like uv raced as many of them as I have. We’ve built some nice ones and finally built one for flat track racing thats ended up being a nightmare. Cheers
Blake
JD Jet Block kit
MJ 490
PJ 32.5
AS 1.5 turns out
Needle jet S4
Needle 42-75 on the 2nd clip
Slide 5.5
Fuel mix 50:1 non ethanol w/Motorex 2T
#anotherHappyCamper
Thanks AJ and Digger!!
If you read any of my posts you know my 2022 125XC still had a hesitation off the bottom with the recommended jetting here. I just never could tune it out no matter what I tried. I believe digger had the same issue on a few bikes, also 2022 125. I could not really wheelie off the bottom/mid with a throttle whack, only when firmly in the powerband.
A local shop suggested the following jetting. Juvenile I know, but a undeniable real world performance test.
After switching to this jetting the bike runs awesome awesome! Wack the throttle from the bottom and it wheelies instantly and goes. It rips from bottom to top and doesnt drool at 40:1 or 50:1. Here is the jetting if you want to try on a 2022 125.
42-71 needle on clip position 2
470 main (stock)
30 pilot
Air screw around 1.5
S7 (stock) needle jet
Stock 4.0 slide
Red powervalve spring from the big bikes at one turn in from full out on the preload adjuster
Block gasket had been done previously
All jetting supplied with the bike from KTM
It also works better with a higher idle (not to high but more than a lope) in my woods riding scenario. Bike starts excellent hot or cold. It will load up at idle but not die, and only this when cold until it warms to temp. After that its good.
Say what you want but this is the best it has run, the most power it has had throughout the rev range, and it finally burns clean. I am now pretty happy with the bottom and mid instant power and this thing rips up top like always.
Your mileage may vary. Just thought I'd post after running it for a few rides in case anyone else wants to try it out. I was skeptical but it just freaking works.
If anyone wants the 5.0 JD slide and 42-74 needle let me know, make an offer.
Matt in GA
*Side effects very, but may include Low blood pressure, nausea, headache, anal leakage, heaving coughing or wheezing, trouble breathing in closed spaces. You may feel dizzy or confused when you see walruses, and have a longing for coconut milk. These side effects occur all the time, 69% of the time. Death is also common among most patients. Brain hemorrhaging can happen too.
I love you too AJ🥰
I just figured I would preface it as it Is such a deviation from the norm here. I am curious if someone else has a 2022 125 and if it works or mine is an oddball. My crank and rod are still in one piece so thats good for a 22 125 already 🤣🤣🤣
can you tell me what's the difference with the red spring compared to the stock one?
Visually, the red should be linear while the stock one has a different turn pattern.
How did the red spring seem to you to the touch compared to the stock one? harder or softer?
How does the delivery of the engine change compared to the stock spring? is the bike more ready when open the throttle?
Thanks
Yes, the power curve is supposed to be more linear with the red. Some people say it takes some of the hit away but makes the bike more powerful and faster everywhere in the rev range. It doesnt remove the "hit" and the bike IS more powerful everywhere. There are dyno charts online of ppl testing the springs back to back and with different preloads. In my research the simplest description is that the harder the spring, and/or the more preload you put on any of the the springs, the more power you are removing from the midrange, which makes the transition to "on the pipe" more severe. While this may fool you into believing the bike is making more power up top, its really just killing the midrange and making the top end feel like its more than it was. Really simple terms: the red spring allows the engine to make the most power everywhere with the most linear power curve and no power removed from the midrange. Even with the red spring, as you dial in preload on that spring, you are creating a hole in the midrange. With the red spring and 1 turn of preload, the bike makes great power from bottom to top. And its a two stroke so you are not ever going to remove the "pipe hit" unless something is seriously wrong. The spring is like $2. I recommend just trying it. Its worth it in spades. If it doesn't do it for you, its only $2 and less than 5 minutes of your time. Search "dyno charts for ktm power valve springs" and you will start to get the picture and see why i went red. Most charts are for the 300s but it works the same on all ktm bikes. Hope this helps. Just buy the damn red spring and install it already! 😄
Pit Row
We tried every needle from 71-76. They didn't make nearly as much of a difference as I would expect. The pilot sizes ranged from 30 to 37.5. The weird thing was that regardless of the pilot size, the air screw needed to be atleast 2 turns out or the engine would load up badly. The nozzle/ needle jet( S-4--S-7) didn't make much of a difference either, unlike I would expect. The slide did make a little difference, but not in the way I wanted it to. Something is just not right with that engine, and without tearing it all the way down, I don't know what's wrong with the bike.
If I could get the 22' bikes back to my shop for a closer look at what is going on, I may be able to figure somethings out, but what we're doing now, testing at the track the day before the races, just doesn't allow me time to really dig into what is going on. It's very frustrating to me, as this is the first time I've run into something like this that i can't pin point to where the problem really is. I had access to 4 newer 125's, all the non 22's run and jet exactly like I would expect them to. The 22's, not so much.
Side note: The slide in the 22' 125, race bike is absolutely shot. The chroming is starting to peel off. This is a non cut or notched #4 oem slide.
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