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0-30celsius I had the MJ always same, rich enough
For spring and autumn one/two size bigger PJ and maybe one clip at the needle when it started to bog on throttle openings
The stock jetting on the 25 85’s is horrendous IMO. I went through hell for about 10hr correcting it. Turns out if it would have just been jetted like a 18-24, it would be fine.
1100’ 45-clip 2-145 seems to be our sweet spot stock. CR8EIX 91non oxy
*edit- I realized I was responding something that wasn’t asked, but if anyone else comes in with a new 85 dumping plugs, hope that helps
Just as a confirmation as I will be grinding my slide to a #5 from a #4 i do not grind the highlighted portion in the image below, I blend up to that portion correct? (The image used is from someone else in the thread and it looks like they actually did grind this part?)
Hey all, after grinding my slide to a #5 as per diggers pictures and help, I got my needles as well and ran the bike (2020 ktm 150sx). I ran it with:
520 main
35 PJ
43-74 needle clip 2
#5 slide (ground 1mm from #4)
Outside temp: -4° C (25° F)
The bike started first kick and idled fine. However after it warmed up for a few seconds I began to put it around for 30 seconds to heat it up. I then tried to clear it out by giving it full throttle in first but the bike would not clear up no matter what. Kept trying to clear it and then it bogged down almost like it ran out of fuel and shut off. Wouldn't start after that, choke on or choke off. Any reason as to why?
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Probably fouled the plug. Things get real weird below freezing. It's hard to get the bike up to full operating temp. Pull the plug and see if it's wet and black.
I honestly figured. Before I made all the carb changes, in its stock form it was doing the same thing in the very cold temps but I brushed it off as poor jetting for the weather. I just ordered a new plug. Ill update once I install it.
On a side note, how do these settings look as a starting point, I know im running the bike in colder temps than most people in the thread just because I wanted to test it, no real riding done below freezing. But thats why im running a rich main, pilot and needle.
First test with new plug, ran up and down the street. Doesn't die anymore runs. However at a low rpm if I pin it it bogs down signature lean bog, this is like fro near idle and and putting it around i first then pin it bogs. Would this be air screw adjustment, needle, or incorrectly ground slide. Jetting is as per above. Also still have a tiny bit of that sputter.
This is the part where jetting over the internet gets hard, lol. I have never ridden my 150 in temps that low. So, I'd only be doing best guestimate on what you should change. It does sound like classic lean pilot bog. There's one surefire way to find out. Put the next size up pilot in.
Got it, thanks for all the help. I don't plan on getting it absolutely dialed in for the winter as I don't do much winter riding but I'll play with Airscrew/PJ. excited for riding season however. guess I get a little eager haha.
Just some casual imput coming from someone who spent a lot of time jetting my 125 in colder winter conditions. As FGR noted an increase in pilot jet is the easy answer to try but i often found in really cold air < 35* that i needed to do both a pilot and clip (try a half clip first) Easy way is get some needle clip spacers so you dont have to buy a million needles while testing. https://www.goodwinperformance.com/product/520-shim-kit/ You can stack these to .5mm which is a half a clip.
Also you should be running the radiator block off per the manual so the motor is at the correct operating temp or all your testing is on a cold motor.
gluck
I have 2020 150sx also, when temps are close to 40 F (sea level) in the morning i have to set the airscrew like 3/4 turn out to make it start and when temps are a little higher in the midday, 1 , 1.25 turn out is sweet spot . So i’d try 37.5 PJ at those temps and avoid to let it idle for too long thats when loads up. Once its warm, try to clear it out in 2nd , 3rd gear
I have a 2019 YZ144 with the Mikuni that I’ve done a lot of testing on for strictly riding moto, track is at about 400 ft and in South Texas. I know the mikuni’s between the YZ and SX are different but trying my jetting may help you with your Mikuni. My bike has an Athena 144, VForce 4, vortex ECU
Jetting:
Main: 460
Pilot: 40 (any leaner and I feel like it it gives up some power down low but it does have a cleaner idle but I have my bike set up not to idle for best throttle response)
Slide: 4 cut to a 5.0
Jet needle: I’ve tried the S1, S4, s7, and S9 (kx125) currently running the S7 from the S4 and I’m really liking the midrange power from the S7.
Needle: I have a ton of different needles that I’ve tried, I have a standard needle from the 04 Kx125 6chj that I put in with the s9 nozzle and it rips but would have to really clear it out.
Current set up is 42-74 clip 3 with the s7 and it’s pulls hard and has no hiccups, or hesisitation, no lean pops, or bog from 1/4-half throttle.
Needles I haven’t tried with the S7 yet that I have are 43-74, 44-74, 42-75, 43-75, 24-74
A/S: 2-2.5 turns out
I keep tabs on this thread as I may pick up a carbed 125SX in the future….but reading through makes me really appreciate my FI 300SX”s..😂…..
The 460 main is way too lean on a KTM125. Those bikes like the fuel.
Better hurry up. Not going to be able to find many decent low hour ones for long. I know people like the TBI 300's, but the TBI 125's are absolute dog poop compared to the carb bikes.
I have been keeping an eye on a few locally…Lower hrs the better for sure…most for sale are ready for a complete overhaul….I had a brand new 22125Sx, put 20hrs on it, with the jetting off this thread….sold it for more than I paid for it, should have kept it, now that I have been riding my 93 Cr125 I feel I would appreciate it more…Vet/+50 125 races seem to be gaining traction in most regions….I”m thinking I may hit the World Vets this fall, they have +50 125 class…..my 2 300sx”s have been magnificent, especially after remaps but that is a different thread…..
Ive ran up to a 480 on my YZ, but took away some over rev. So 460 for summer and 470-480 in the winter.
Also running a richer jet needle s7 (s9 being the richest) you may be able to get away with a leaner main. 420-430 I think is STD main for the YZ.
Pit Row
The setup you describe (42-74 clip 3 with the s7 ) would certainly make it richer in the middle (compared to a 42-74 with an S4). However, with a small-ish 460 main, the S7 makes no difference on the top end as the main jet becomes the constraining factor. As AJ said, the Austrian 125/150 likes a lot more fuel on the extreme top than the YZ125's do. Hence why the specs in this thread are in the 500-540 main jet range.
Hey all,
Coming back in to see what your guys suggestions are for the mods im about to do. Currently im running the spec thats in this thread on a 2020 ktm 150sx
510 Main
32.5 pilot
42 - 74 needle clip 2
AS 2 turns out
PV 1.75 turns in from all the way out.
Also got the pro circuit r304. Bike run amazing as of now. However I'm thinking of adding the pro circuit platinum and the vforce 4r reeds. Would these require a jetting change? And if so in what direction. Im more concerned with the pipe as i heard the reeds dont need any change. Also as a side note:
- do you guys recomend the rad valve or v force 4r?
Thanks.
The Vforce will likely make no change since they are pretty much identical to the stock reeds. I’ve use many different pipes and never really needed to adjust jetting. But I never tried the PC pipe. Doubt it would require much jetting change.
Never tried the Rad Valve on these bikes. You will have to let us know how that goes.
Thats good to hear, since the bike runs so well right now i didn't want the changes to mess it up haha. I've heard lots of good about the pro circuit system on the 150's so ill try it out and see how it goes. The r304 itself was a big improvement.
Nice bike!.. i have the same 2020 with almost same jetting . sea level 50-65F range temp 520, 35 , 42-74 pos 2, AS 1.75 . PV 1.25 and in few days im gonna try the red spring and Boyesen Super stock reeds .
For the 185-200lbs owners in this thread….if any… rear shock spring rate?
193 nude…
I use a 4.8
Better than the 4.5 and the stock spring (4,2?) way too soft
Excellent… thanks….going to look at a 22 150SX this week…like I need another bike😂
Last year i was on 190lbs and i put on my 150sx a 4.4kg rear spring Race tech with great results and 140psi in front fork , now im 171lbs and i had a hard time getting the right sag without gear, the best i could get is 103mm sag , i think with full gear i reach the 105 mark . Stock spring is 39 NM
Are you guys using a 32.5 pilot in the 150sx ? I am down to a 25 pilot in mine with the cut slide. I could see it working in the125 but what is best for the 150.
Hey, heads up there’s a 4.8 for sale in classified and it’s not me
20+ shipping that’s cheaper than the six beers you’ll drink on the way back from the track
In summer sea level i use 32.5 pilot with the #5 slide , no notch. Below 75-70 temp i change to 35 and my bike when temps reach to 40F my air screw is at 1 turn and maybe i can drop 37.5 but that temp is early in the morning. Usually i set the Air screw at 1.5 turns
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