125/150/250/300 KTM/HUS/GG jetting thread

3/23/2024 1:59pm
AJ565 wrote:
  This is my bike with PC pipe and 304 silencer at the time running u4.4 at 60:1 with just the jetting from page 1. 2018...

IMG 3248.png?VersionId=WtsaqvtG.zGWe7yU6Q1QCrZkFBcYS
 

This is my bike with PC pipe and 304 silencer at the time running u4.4 at 60:1 with just the jetting from page 1. 2018 250sx

wich powervalve spring ?

rickycoffin
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Location
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3/29/2024 9:36am

Digger, 

I was trying to find the post about the notch in the slide. I have a 2018 and a 2019 ktm 150 sx that I am preparing to file the slides notchs. What depth do I go to? 

I am currently running

Slide #5

Main 490

Pilot 30- had a 35 but it was too rich and I have 32.5 and 27.5 coming to try

needle- 42-74

JD gasket

Bike runs better with these settings but want to clean up the idle. 

 

digger
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3/29/2024 4:13pm Edited Date/Time 3/29/2024 4:16pm
Digger,  I was trying to find the post about the notch in the slide. I have a 2018 and a 2019 ktm 150 sx that I...

Digger, 

I was trying to find the post about the notch in the slide. I have a 2018 and a 2019 ktm 150 sx that I am preparing to file the slides notchs. What depth do I go to? 

I am currently running

Slide #5

Main 490

Pilot 30- had a 35 but it was too rich and I have 32.5 and 27.5 coming to try

needle- 42-74

JD gasket

Bike runs better with these settings but want to clean up the idle. 

 

Ricky, I use a 5/32 or 4mm chainsaw file, and file down about 3mm in depth. It's not super critical, like filing the other side of the slide is. There is a pic on page 5 in this thread of a slide that I cut and notched that will give you and idea of what I'm doing, and how deep to go with the notch.

3/31/2024 12:11am
AJ565 wrote:
I get a lot of emails from here and at the track about jetting for the 2 strokes. Thanks to digger for pointing me in the...

I get a lot of emails from here and at the track about jetting for the 2 strokes. Thanks to digger for pointing me in the right direction this is the currant specs. I have for everything. Its easier to start a thread With all the jetting in it to keep track of everything. Your jetting might need tweaked based on your temps and elevation, but this is a good start for you.

**Updated 4/19/23**
'17+ 125/150 jetting (‘22 bikes have a known bog, there is no jetting or carb swap combo yet that takes care of that problem. If or when it gets figured out I’ll update)


MJ 510
PJ 32.5
AS 1.75
slide 5.0 from JD Jetting
Needle 42-74 on the 2nd clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 2.25 turns in from all the way out.
Fuel mix 40:1

(credit to FGR01 for continuing to refine the small bore jetting)


On the '17+ 250's **Updated 10/13/2020**
Pump gas/race gas or straight C12

This is my current jetting. Its more refined all around and crisp down low with better top end over rev.

Main jet 500
Pilot jet 32.5
Slide 5.75 (Kawasaki part#16025-0003)
Needle 43-75 (KTM part #55431134400)
Clip position #2
Needle jet S4 (KTM part #55431021400)
Air screw 1.5-2.0
Fuel 55:1

OR

Solid jetting if you're someone that doesn't live on top end. Crisp down low out of turns pull.
MJ 490
PJ 32.5
AS 1.5 turns out
Needle jet S4 (KTM part #55431021400) stock is S1
Needle 42-75 on the 2nd clip (Yamaha part #284-14116-H5-00)
Slide 5.5 (Kawasaki part 16025-0002)
PV 1.75 turns in from all the way out
Fuel mix 50:1

300sx jetting

Pilot jet 25 and main jet 460 to start.
Slide 5.5 (Kawasaki part 16025-0002)
Needle 42-75 on the 2nd clip (Yamaha part #284-14116-H5-00)
5/32” chainsaw file to notch the front of the slide.
A/S 1.5 to start, you’ll need to adjust as needed.
 

Hi, do you have new jetting information for 300sx. I also have a 300 but I have difficulty adjusting it correctly, I drive it like a 125...

Hi, do you have new jetting information for 300sx. I also have a 300 but I have difficulty adjusting it correctly, I drive it like a 125, in deep sand.

450

32,5

44-75 2nd position

A/S:2

IMG 9313

FGR01 wrote:
Yup, you need the slide like AJ said.  Look a few posts above for what I am running in my 300.  I am not riding deep...

Yup, you need the slide like AJ said.  Look a few posts above for what I am running in my 300.  I am not riding deep sand but I feel like this jetting is on the "safe" side and would at least be a very close starting point to get you going.   I'd be afraid to run a 450 main in sand !

300:
PJ  35
Main 500
Needle  43-75, clip 2
Needle Jet    S4
Slide 5.75
AS   1.5 - 1.75
Motul 800 at 38:1 with 100LL AvGas

Hi guys, I’m back with your jetting.I don't have the needle so I imagine it should still work better with it.. actually the bike works well even with the wrong needle (currently 44-75 2nd clip). I order and install the right needle and go. I found a needle chart (in French because I'm French 🤪)IMG 9386IMG 9382

The Shop

FGR01
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3/31/2024 7:47am
Hi, do you have new jetting information for 300sx. I also have a 300 but I have difficulty adjusting it correctly, I drive it like a 125...

Hi, do you have new jetting information for 300sx. I also have a 300 but I have difficulty adjusting it correctly, I drive it like a 125, in deep sand.

450

32,5

44-75 2nd position

A/S:2

IMG 9313

FGR01 wrote:
Yup, you need the slide like AJ said.  Look a few posts above for what I am running in my 300.  I am not riding deep...

Yup, you need the slide like AJ said.  Look a few posts above for what I am running in my 300.  I am not riding deep sand but I feel like this jetting is on the "safe" side and would at least be a very close starting point to get you going.   I'd be afraid to run a 450 main in sand !

300:
PJ  35
Main 500
Needle  43-75, clip 2
Needle Jet    S4
Slide 5.75
AS   1.5 - 1.75
Motul 800 at 38:1 with 100LL AvGas

Hi guys, I’m back with your jetting.I don't have the needle so I imagine it should still work better with it.. actually the bike works well even...

Hi guys, I’m back with your jetting.I don't have the needle so I imagine it should still work better with it.. actually the bike works well even with the wrong needle (currently 44-75 2nd clip). I order and install the right needle and go. I found a needle chart (in French because I'm French 🤪)IMG 9386IMG 9382

OK, so it's running good?    Yeah 44-75  essentially has grooves cut 1 whole clip richer than 42-75.  So, 44-75(2) basically equals 42-75(3).  This might not be a bad thing since you're in sand.  But, like you said, I would still try 43-75(2) just to be sure and compare.

1
4/2/2024 3:17am Edited Date/Time 4/2/2024 3:19am
AJ565 wrote:
I get a lot of emails from here and at the track about jetting for the 2 strokes. Thanks to digger for pointing me in the...

I get a lot of emails from here and at the track about jetting for the 2 strokes. Thanks to digger for pointing me in the right direction this is the currant specs. I have for everything. Its easier to start a thread With all the jetting in it to keep track of everything. Your jetting might need tweaked based on your temps and elevation, but this is a good start for you.

**Updated 4/19/23**
'17+ 125/150 jetting (‘22 bikes have a known bog, there is no jetting or carb swap combo yet that takes care of that problem. If or when it gets figured out I’ll update)


MJ 510
PJ 32.5
AS 1.75
slide 5.0 from JD Jetting
Needle 42-74 on the 2nd clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 2.25 turns in from all the way out.
Fuel mix 40:1

(credit to FGR01 for continuing to refine the small bore jetting)


On the '17+ 250's **Updated 10/13/2020**
Pump gas/race gas or straight C12

This is my current jetting. Its more refined all around and crisp down low with better top end over rev.

Main jet 500
Pilot jet 32.5
Slide 5.75 (Kawasaki part#16025-0003)
Needle 43-75 (KTM part #55431134400)
Clip position #2
Needle jet S4 (KTM part #55431021400)
Air screw 1.5-2.0
Fuel 55:1

OR

Solid jetting if you're someone that doesn't live on top end. Crisp down low out of turns pull.
MJ 490
PJ 32.5
AS 1.5 turns out
Needle jet S4 (KTM part #55431021400) stock is S1
Needle 42-75 on the 2nd clip (Yamaha part #284-14116-H5-00)
Slide 5.5 (Kawasaki part 16025-0002)
PV 1.75 turns in from all the way out
Fuel mix 50:1

300sx jetting

Pilot jet 25 and main jet 460 to start.
Slide 5.5 (Kawasaki part 16025-0002)
Needle 42-75 on the 2nd clip (Yamaha part #284-14116-H5-00)
5/32” chainsaw file to notch the front of the slide.
A/S 1.5 to start, you’ll need to adjust as needed.
 

Hi, I’ve bought a ktm 150 sx 2017 and I’m struggling to get the mikuni carb right. I’ve changed the jet block gasket from JD.

I’ve ordered all the parts in your suggested carb settings for the 17+ 150 hoping to solve the bike it bogs in 1st & 2nd as if it colds when it’s not then picks up. It’s not running crisp like a two stroke should it’s not screaming like a 150 should. 

pump gas 98 @ 40:1 2t motorex oil

UK

4/6/2024 6:16pm

2022 125SX

MJ 540
PJ 32.5
AS 1.50
slide 5.0 from JD Jetting
Needle 42-74 on the 3rd clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 1.5 turns in from all the way out.
Fuel mix 91pump/U4.4 2:1   Motorex 36:1

Warning the bike will run very fast on this jet and fuel mix but will run hot. just cracked a head today at ACP. both the piston top and plug were chalk white. very lean. I had an exhaust o ring fail also that may have pushed the lean condition.

after the rebuild im considering

 MJ 540
PJ 35
AS 1.0
slide 5.0 from JD Jetting
Needle 42-74 on the 4th clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 1.5 turns in from all the way out.
Fuel mix 91pump/U4.4 2:1   Motorex 36:1

is there another needle jet that can open the fuel up 5%, maybe the stock S1. Am i correct in thinking the needle jet will affect my main jet. Im up to a 540 from the stock 500 and its still lean. I think there is one bigger main jet i can get, but is there diminishing returns on the bigger jets. the bike too rich with this fuel mix stock and too lean now. I just need a little more fuel.

 

FGR01
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4/8/2024 8:43pm
2022 125SX MJ 540 PJ 32.5 AS 1.50 slide 5.0 from JD Jetting Needle 42-74 on the 3rd clip (Yamaha 284-14116-H4-00) Needle jet S4 (KTM part...

2022 125SX

MJ 540
PJ 32.5
AS 1.50
slide 5.0 from JD Jetting
Needle 42-74 on the 3rd clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 1.5 turns in from all the way out.
Fuel mix 91pump/U4.4 2:1   Motorex 36:1

Warning the bike will run very fast on this jet and fuel mix but will run hot. just cracked a head today at ACP. both the piston top and plug were chalk white. very lean. I had an exhaust o ring fail also that may have pushed the lean condition.

after the rebuild im considering

 MJ 540
PJ 35
AS 1.0
slide 5.0 from JD Jetting
Needle 42-74 on the 4th clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 1.5 turns in from all the way out.
Fuel mix 91pump/U4.4 2:1   Motorex 36:1

is there another needle jet that can open the fuel up 5%, maybe the stock S1. Am i correct in thinking the needle jet will affect my main jet. Im up to a 540 from the stock 500 and its still lean. I think there is one bigger main jet i can get, but is there diminishing returns on the bigger jets. the bike too rich with this fuel mix stock and too lean now. I just need a little more fuel.

 

The S1 is leaner than the S4.  You want the S7 to make it richer.  Also, on the 2022 bikes I ended up on a 37.5 pilot running AvGas which is non-Oxy.   You probably need to go richer on the pilot and/or needle straight section (like to a 42-72 or so) as well.  Ultimately you'll need to find the right combo of Needle-jet and Jet-needle to work correctly across the whole range.

4/11/2024 8:52pm
2022 125SX MJ 540 PJ 32.5 AS 1.50 slide 5.0 from JD Jetting Needle 42-74 on the 3rd clip (Yamaha 284-14116-H4-00) Needle jet S4 (KTM part...

2022 125SX

MJ 540
PJ 32.5
AS 1.50
slide 5.0 from JD Jetting
Needle 42-74 on the 3rd clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 1.5 turns in from all the way out.
Fuel mix 91pump/U4.4 2:1   Motorex 36:1

Warning the bike will run very fast on this jet and fuel mix but will run hot. just cracked a head today at ACP. both the piston top and plug were chalk white. very lean. I had an exhaust o ring fail also that may have pushed the lean condition.

after the rebuild im considering

 MJ 540
PJ 35
AS 1.0
slide 5.0 from JD Jetting
Needle 42-74 on the 4th clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 1.5 turns in from all the way out.
Fuel mix 91pump/U4.4 2:1   Motorex 36:1

is there another needle jet that can open the fuel up 5%, maybe the stock S1. Am i correct in thinking the needle jet will affect my main jet. Im up to a 540 from the stock 500 and its still lean. I think there is one bigger main jet i can get, but is there diminishing returns on the bigger jets. the bike too rich with this fuel mix stock and too lean now. I just need a little more fuel.

 

FGR01 wrote:
The S1 is leaner than the S4.  You want the S7 to make it richer.  Also, on the 2022 bikes I ended up on a 37.5...

The S1 is leaner than the S4.  You want the S7 to make it richer.  Also, on the 2022 bikes I ended up on a 37.5 pilot running AvGas which is non-Oxy.   You probably need to go richer on the pilot and/or needle straight section (like to a 42-72 or so) as well.  Ultimately you'll need to find the right combo of Needle-jet and Jet-needle to work correctly across the whole range.

Thank you for your input. I have new parts on order and will continue testing.

ivanb1
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Location
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4/16/2024 10:07pm Edited Date/Time 4/16/2024 10:11pm

Hi from Argentina! Ive read the 35 Pages of this Amazing topic. Somebody knows what needle jet ( S1 or S4) comes in 2017 150sx from factory and where is located in carb ? .

Planing go with this 

Sea level , between 50°F and 77°F most of the year. running Pump gas. Shell Vpower.

Begginer 180lbs without gear.

(40/50°F Winter sand/dunes conditions)*

MJ 500 (540)*

PJ 35 (37.5)*

Slide #5 JD jetting without notch

S4

Needle 42-74 2 pos (3 pos) *

I hope You can confirm if im in the right direction with this. Thank You all, for be SO active in this topic. 

FGR01
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Location
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4/17/2024 3:43am
ivanb1 wrote:
Hi from Argentina! Ive read the 35 Pages of this Amazing topic. Somebody knows what needle jet ( S1 or S4) comes in 2017 150sx from...

Hi from Argentina! Ive read the 35 Pages of this Amazing topic. Somebody knows what needle jet ( S1 or S4) comes in 2017 150sx from factory and where is located in carb ? .

Planing go with this 

Sea level , between 50°F and 77°F most of the year. running Pump gas. Shell Vpower.

Begginer 180lbs without gear.

(40/50°F Winter sand/dunes conditions)*

MJ 500 (540)*

PJ 35 (37.5)*

Slide #5 JD jetting without notch

S4

Needle 42-74 2 pos (3 pos) *

I hope You can confirm if im in the right direction with this. Thank You all, for be SO active in this topic. 

That sounds like some good starting points for you.

Make sure you check the float height also to 8 - 9mm.

From the manual, your bike has the S-1:
image-20240417033806-1

To Remove the needle-Jet, remove slide assembly, remove carb from bike, remove float bowl and float, remove main jet, and then remove the 8mm brass nut under main jet (Main jet holder).  The needle-Jet is behind that.  If it does not fall out the bottom easy, use a tool and push down gently from the top of the carb and it should fall out.

When you have all this apart, you should remove the 2-torx screws and replace the jet block gasket also to make sure that is fresh and sealed well.
https://jdjetting.com/product/jdmk05-mikuni-tmx-jet-block-kit/

 

1
old144
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Location
Alvsjo SE
4/18/2024 9:33am

Hi, 

Tried to find information in this huge thread but think I came up short. I have a Husky TC 125 2020 that is now equipped with KTM complete new 150 kit. The call it factory but I believe it is bog standard 150SX kit or? 
 

Now my real question, the former owner had the TMX38 carb bored out so now I measured it to 40mm, how does this affect jetting? Bike is really bad on low to maybe’s mid throttle with 4.0 slide and jetting according 150 manual.  I would say uneven and sputters. 

Live in sweden so spring for us now is 40-50F, sea lvl. Have JD gasket. Float looks ok at 60 degrees. Just got a 5.0 slide installed. Have standard needles/jets and JD kit needles/jets for 125. Do not know if the are the same in JD 150 kit. To make matters even worse I will run it mostly on sand MX tracks but I’m only dreaming of wide open, it does not happen in real life. So any jetting advice would be much appreciated.

/Robert

old144
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4/25/2024 10:24am

Yeah, still struggling so I will answer myselfSmile  

Tried to file down my 4.0 slide to a leaner but it looks more like a 5.0 so far. Still used it last time and here are my findings. Rather cold around 9 degrees Celsius cooling down towards 6c later on. Riding rather heavy sand mx-track. Started with 520/35 and 42-71 on 3rd. Sounds and goes like a lawnmower down lowSad thought it went better when adjusting airscrew out 1 1/2 turn so went down to a 30 pilot and put airscrew back at 1 2/3.

 

Didn’t really notice any improvement so moved clip up to second. Maybe a slight improvement but still rather bad when trying to maintain a steady (low) trottle. Should I continue moving to first clip or find a leaner needle? A bit unsure to make it leaner since since riding sand and cold temperatures? Could my drilled out carb (40mm) cause me all this headache? 

TDC
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4/25/2024 2:10pm
old144 wrote:
Yeah, still struggling so I will answer myself:)  Tried to file down my 4.0 slide to a leaner but it looks more like a 5.0 so...

Yeah, still struggling so I will answer myselfSmile  

Tried to file down my 4.0 slide to a leaner but it looks more like a 5.0 so far. Still used it last time and here are my findings. Rather cold around 9 degrees Celsius cooling down towards 6c later on. Riding rather heavy sand mx-track. Started with 520/35 and 42-71 on 3rd. Sounds and goes like a lawnmower down lowSad thought it went better when adjusting airscrew out 1 1/2 turn so went down to a 30 pilot and put airscrew back at 1 2/3.

 

Didn’t really notice any improvement so moved clip up to second. Maybe a slight improvement but still rather bad when trying to maintain a steady (low) trottle. Should I continue moving to first clip or find a leaner needle? A bit unsure to make it leaner since since riding sand and cold temperatures? Could my drilled out carb (40mm) cause me all this headache? 

Time for the ole DIY larger slide notch. 

5/4/2024 6:47pm Edited Date/Time 5/4/2024 6:48pm

Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today the bike at 4500ft was running rich

My motor was full of oil where the connection pipe/silencer and this is my spark with just two hrs

any advice please 🙏🏼

FGR01
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5/4/2024 8:20pm
Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today...

Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today the bike at 4500ft was running rich

My motor was full of oil where the connection pipe/silencer and this is my spark with just two hrs

any advice please 🙏🏼

Tell us what fuel, oil, and ratio you are using and also what jetting is in the carb now.

5/4/2024 9:52pm
Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today...

Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today the bike at 4500ft was running rich

My motor was full of oil where the connection pipe/silencer and this is my spark with just two hrs

any advice please 🙏🏼

FGR01 wrote:

Tell us what fuel, oil, and ratio you are using and also what jetting is in the carb now.

Fuel 91 Motorex oil 40:1 tomorrow I will open the carb and I will let you know wat jetting 🙏🏼🙏🏼

5/5/2024 2:34pm
Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today...

Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today the bike at 4500ft was running rich

My motor was full of oil where the connection pipe/silencer and this is my spark with just two hrs

any advice please 🙏🏼

FGR01 wrote:

Tell us what fuel, oil, and ratio you are using and also what jetting is in the carb now.

Hello so it is what I have so far

5/5/2024 2:34pm
Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today...

Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today the bike at 4500ft was running rich

My motor was full of oil where the connection pipe/silencer and this is my spark with just two hrs

any advice please 🙏🏼

FGR01 wrote:

Tell us what fuel, oil, and ratio you are using and also what jetting is in the carb now.

Hello so it is what I have so far

Hello so it is what I have so far

5/5/2024 2:35pm
Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today...

Hi I have a 2022 Ktm 150 sx with Keihin carburetor and I just installed a Scalvini racing works pipe with full carbon silencer and today the bike at 4500ft was running rich

My motor was full of oil where the connection pipe/silencer and this is my spark with just two hrs

any advice please 🙏🏼

FGR01 wrote:

Tell us what fuel, oil, and ratio you are using and also what jetting is in the carb now.

Fuel 91 Motorex oil 40:1 tomorrow I will open the carb and I will let you know wat jetting 🙏🏼🙏🏼


 

I can’t read any numbers on the needle 

FGR01
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5/5/2024 4:21pm
FGR01 wrote:

Tell us what fuel, oil, and ratio you are using and also what jetting is in the carb now.

Fuel 91 Motorex oil 40:1 tomorrow I will open the carb and I will let you know wat jetting 🙏🏼🙏🏼

  I can’t read any numbers on the needle 


 

I can’t read any numbers on the needle 

The needle number will be stamped here.. use the zoom function on your phone to read it...

image-20240505162129-1

FGR01
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5/5/2024 4:32pm

In the meantime, I will say that you'll likely be much better off by simply raising the needle clip 1 or 2 positions.   You're currently in the 2nd richest position there which is likely excessive for 4500ft, especially if the temperature is also warm.

1
5/5/2024 4:55pm
FGR01 wrote:
In the meantime, I will say that you'll likely be much better off by simply raising the needle clip 1 or 2 positions.   You're currently in...

In the meantime, I will say that you'll likely be much better off by simply raising the needle clip 1 or 2 positions.   You're currently in the 2nd richest position there which is likely excessive for 4500ft, especially if the temperature is also warm.

Thanks a lot I will do it and I did try to read with the phone on the needle but there is nothing stamped, I do have another needle number 6BFY44-73 the previous owner gave it to me should I use it?..and I also did some research and I see people using PJ 40 instead than 42..what you think?

Thanks again for the help 

FGR01
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5/5/2024 6:12pm
Thanks a lot I will do it and I did try to read with the phone on the needle but there is nothing stamped, I do...

Thanks a lot I will do it and I did try to read with the phone on the needle but there is nothing stamped, I do have another needle number 6BFY44-73 the previous owner gave it to me should I use it?..and I also did some research and I see people using PJ 40 instead than 42..what you think?

Thanks again for the help 

The 6BFY44-73 is a Mikuni needle.  Won't work in your Keihin.   

For now I would try moving the clip up 1 position.  1 change at a time or else you might get yourself lost with changes.

1
ivanb1
Posts
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4/16/2024
Location
Buenos Aires , Buenos Aires AR
5/5/2024 7:05pm
2022 125SX MJ 540 PJ 32.5 AS 1.50 slide 5.0 from JD Jetting Needle 42-74 on the 3rd clip (Yamaha 284-14116-H4-00) Needle jet S4 (KTM part...

2022 125SX

MJ 540
PJ 32.5
AS 1.50
slide 5.0 from JD Jetting
Needle 42-74 on the 3rd clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 1.5 turns in from all the way out.
Fuel mix 91pump/U4.4 2:1   Motorex 36:1

Warning the bike will run very fast on this jet and fuel mix but will run hot. just cracked a head today at ACP. both the piston top and plug were chalk white. very lean. I had an exhaust o ring fail also that may have pushed the lean condition.

after the rebuild im considering

 MJ 540
PJ 35
AS 1.0
slide 5.0 from JD Jetting
Needle 42-74 on the 4th clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 1.5 turns in from all the way out.
Fuel mix 91pump/U4.4 2:1   Motorex 36:1

is there another needle jet that can open the fuel up 5%, maybe the stock S1. Am i correct in thinking the needle jet will affect my main jet. Im up to a 540 from the stock 500 and its still lean. I think there is one bigger main jet i can get, but is there diminishing returns on the bigger jets. the bike too rich with this fuel mix stock and too lean now. I just need a little more fuel.

 

Yes, in other pages they recommend at least, 35 PJ if You don't notch the slide . 32.5 if You notched the slide .also you can try running 40:1 premix. Check float level heigth. 

5/5/2024 7:53pm
Thanks a lot I will do it and I did try to read with the phone on the needle but there is nothing stamped, I do...

Thanks a lot I will do it and I did try to read with the phone on the needle but there is nothing stamped, I do have another needle number 6BFY44-73 the previous owner gave it to me should I use it?..and I also did some research and I see people using PJ 40 instead than 42..what you think?

Thanks again for the help 

FGR01 wrote:
The 6BFY44-73 is a Mikuni needle.  Won't work in your Keihin.    For now I would try moving the clip up 1 position.  1 change at a...

The 6BFY44-73 is a Mikuni needle.  Won't work in your Keihin.   

For now I would try moving the clip up 1 position.  1 change at a time or else you might get yourself lost with changes.


I actually found this online for Keihin carb..what do you think? 

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FGR01
Posts
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10/1/2006
Location
AZ US
Fantasy
1312th
5/5/2024 8:38pm
I actually found this online for Keihin carb..what do you think? 


I actually found this online for Keihin carb..what do you think? 

If that is the NOZI needle you have, it may be somewhat useful.  Also, assuming you have the same size slide that the 150 came with when it had the Keihin that chart is for.   That shows clip#2 for your elevation and mid-temps so I'd try 3 and then 2 and see what it gives you.

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