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

FGR01
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11/5/2023 11:28am
Thanks for the help!  I thing I will start of with my old carb settings and my old slide since my whole engine is brand new...

Thanks for the help! 

I thing I will start of with my old carb settings and my old slide since my whole engine is brand new. After break in I will try the new settings with the new slide. I order the 5.0 Slide because I thought the 6.0 Slide would be to lean. I will try the lean JD Jetting Needle first and then see how it goes with the new Slide and new needle jet. 

 

TDC wrote:

Have you taken a look at the PC jetting web page and/or the jetting sub-forum on KTMtalk? 

Keihin conversion simplifies life. As I'm sure you've read. 

Ha!  PC specs are joke.  Both in general and especially for any Austrian bike with a Mikuni.   Those specs only address pilot and main and assume you will use the stock slide and needle.  They also assume you will use either MRXO2 or C12.

TDC
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11/5/2023 11:42am
Thanks for the help!  I thing I will start of with my old carb settings and my old slide since my whole engine is brand new...

Thanks for the help! 

I thing I will start of with my old carb settings and my old slide since my whole engine is brand new. After break in I will try the new settings with the new slide. I order the 5.0 Slide because I thought the 6.0 Slide would be to lean. I will try the lean JD Jetting Needle first and then see how it goes with the new Slide and new needle jet. 

 

TDC wrote:

Have you taken a look at the PC jetting web page and/or the jetting sub-forum on KTMtalk? 

Keihin conversion simplifies life. As I'm sure you've read. 

FGR01 wrote:
Ha!  PC specs are joke.  Both in general and especially for any Austrian bike with a Mikuni.   Those specs only address pilot and main and assume...

Ha!  PC specs are joke.  Both in general and especially for any Austrian bike with a Mikuni.   Those specs only address pilot and main and assume you will use the stock slide and needle.  They also assume you will use either MRXO2 or C12.

Didn't know that. So off to TT or KTMTalk. 

AJ565
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11/5/2023 3:24pm
After posting I pulled the float valve seat out, and the O-ring fell apart the moment I put my pick tool on it. Would that O-ring...

After posting I pulled the float valve seat out, and the O-ring fell apart the moment I put my pick tool on it. Would that O-ring leaking cause overly rich conditions in spite of jetting otherwise being to spec? 

 

float valve seat and o ring

Yes it can by letting more fuel into the bowl since it’s going around the valve. Depending on how bad that o-ring is it normally leaks onto the ground as well. 

queen of spodes
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11/5/2023 4:49pm

Would dropping from 500 to 470 be safe? I am pretty slow, and torque my bike around the track more than I am running hard in upper rpm.  I ride at roughly 800' elevation. 

The Shop

#434
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11/7/2023 8:34am
Would dropping from 500 to 470 be safe? I am pretty slow, and torque my bike around the track more than I am running hard in...

Would dropping from 500 to 470 be safe? I am pretty slow, and torque my bike around the track more than I am running hard in upper rpm.  I ride at roughly 800' elevation. 

Shouldn’t be a problem.

If you don’t open the throttle fully, the main jet has actually little impact on the mixture. The combination of needle and needle jet plus the offset of the pilot system is the important parts for most slow to intermediate guys that don’t ride very deep stuff or aren’t very heavy.

I always went one size down from the recommended setting (KTM for Keihin carb) when I was riding hard pack and stuck to the recommended settings when the track was deep or when I felt in shape and could push.

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queen of spodes
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11/8/2023 3:43pm
Would dropping from 500 to 470 be safe? I am pretty slow, and torque my bike around the track more than I am running hard in...

Would dropping from 500 to 470 be safe? I am pretty slow, and torque my bike around the track more than I am running hard in upper rpm.  I ride at roughly 800' elevation. 

#434 wrote:
Shouldn’t be a problem. If you don’t open the throttle fully, the main jet has actually little impact on the mixture. The combination of needle and...

Shouldn’t be a problem.

If you don’t open the throttle fully, the main jet has actually little impact on the mixture. The combination of needle and needle jet plus the offset of the pilot system is the important parts for most slow to intermediate guys that don’t ride very deep stuff or aren’t very heavy.

I always went one size down from the recommended setting (KTM for Keihin carb) when I was riding hard pack and stuck to the recommended settings when the track was deep or when I felt in shape and could push.

While carb is apart I discovered the float height was 7.3mm. I'm reading that would cause a rich condition. I set it to 8.5mm, and will reinstall the 500 main so as not to change too many things at once. 

Question on throttle cable routing. I wasn't able to rotate the carb far enough to access drain plug, the cable wasn't long enough. Should I route the throttle cable behind the handlebar for that extra clearance? I am not running bar risers. 

FGR01
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11/8/2023 5:35pm
While carb is apart I discovered the float height was 7.3mm. I'm reading that would cause a rich condition. I set it to 8.5mm, and will...

While carb is apart I discovered the float height was 7.3mm. I'm reading that would cause a rich condition. I set it to 8.5mm, and will reinstall the 500 main so as not to change too many things at once. 

Question on throttle cable routing. I wasn't able to rotate the carb far enough to access drain plug, the cable wasn't long enough. Should I route the throttle cable behind the handlebar for that extra clearance? I am not running bar risers. 

Standard routing is behind the bars.  Yes, it will be very tight and not give you slack to rotate the carb if it in front of the bars.

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#434
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11/8/2023 11:47pm
Would dropping from 500 to 470 be safe? I am pretty slow, and torque my bike around the track more than I am running hard in...

Would dropping from 500 to 470 be safe? I am pretty slow, and torque my bike around the track more than I am running hard in upper rpm.  I ride at roughly 800' elevation. 

#434 wrote:
Shouldn’t be a problem. If you don’t open the throttle fully, the main jet has actually little impact on the mixture. The combination of needle and...

Shouldn’t be a problem.

If you don’t open the throttle fully, the main jet has actually little impact on the mixture. The combination of needle and needle jet plus the offset of the pilot system is the important parts for most slow to intermediate guys that don’t ride very deep stuff or aren’t very heavy.

I always went one size down from the recommended setting (KTM for Keihin carb) when I was riding hard pack and stuck to the recommended settings when the track was deep or when I felt in shape and could push.

While carb is apart I discovered the float height was 7.3mm. I'm reading that would cause a rich condition. I set it to 8.5mm, and will...

While carb is apart I discovered the float height was 7.3mm. I'm reading that would cause a rich condition. I set it to 8.5mm, and will reinstall the 500 main so as not to change too many things at once. 

Question on throttle cable routing. I wasn't able to rotate the carb far enough to access drain plug, the cable wasn't long enough. Should I route the throttle cable behind the handlebar for that extra clearance? I am not running bar risers. 

Yes, put everything to spec (float height, this dammed o-ring, check the spark plug, air filter…) before playing around with settings.

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Jon_Haynes
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11/13/2023 7:25am

where are you guys at jetting wise on a 2022 Husky tc with a 150 cylinder ? I just bought a low hour bike. only rode for about minutes on it so far but I do feel a slight boog when hitting  the throttle. It will be my moto cross bike for a old slow guy. Thanks

AJ565
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11/13/2023 10:34am
Jon_Haynes wrote:
where are you guys at jetting wise on a 2022 Husky tc with a 150 cylinder ? I just bought a low hour bike. only rode...

where are you guys at jetting wise on a 2022 Husky tc with a 150 cylinder ? I just bought a low hour bike. only rode for about minutes on it so far but I do feel a slight boog when hitting  the throttle. It will be my moto cross bike for a old slow guy. Thanks

If you read back through a few pages they’ve had issues with that bog and it didn’t matter what jetting or carb swapped into the bike it never went away. There is some solid jetting those guys worked to, but for some reason the 2022 125/150 has the bog. 

FGR01
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11/13/2023 11:01am
Jon_Haynes wrote:
where are you guys at jetting wise on a 2022 Husky tc with a 150 cylinder ? I just bought a low hour bike. only rode...

where are you guys at jetting wise on a 2022 Husky tc with a 150 cylinder ? I just bought a low hour bike. only rode for about minutes on it so far but I do feel a slight boog when hitting  the throttle. It will be my moto cross bike for a old slow guy. Thanks

AJ565 wrote:
If you read back through a few pages they’ve had issues with that bog and it didn’t matter what jetting or carb swapped into the bike...

If you read back through a few pages they’ve had issues with that bog and it didn’t matter what jetting or carb swapped into the bike it never went away. There is some solid jetting those guys worked to, but for some reason the 2022 125/150 has the bog. 

I got one of the newer bikes running great.  Check my post on page 32 with the video.   Basically it needed a leaner needle than the older bikes to get rid of the rich throttle-snap bog.  I had the same finding using a Keihin on the same bike - needed a leaner needle than the older bikes.

Jon_Haynes
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11/13/2023 3:33pm

Thanks guys, I will give that a try. Looks like I better order some jets and a slide. Does the Lectron get rid of the bog at all? Thanks again.

FGR01
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11/13/2023 9:33pm
Jon_Haynes wrote:
Thanks guys, I will give that a try. Looks like I better order some jets and a slide. Does the Lectron get rid of the bog...

Thanks guys, I will give that a try. Looks like I better order some jets and a slide. Does the Lectron get rid of the bog at all? Thanks again.

Lectron is a totally different ball game.  Yes, it can get rid of that bog, but it may require a little fiddling to get it perfect.  They are not always as "Plug N play" as they are made out to be.  And a Lectron will cost a whole lot more than the parts for the Mikuni.  You may not hit the target first try on the Mikuni.  It likely will require some fiddling and fine tuning to allow for the your local conditions and fuel and oil mix.

thekybo
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11/15/2023 11:07am Edited Date/Time 11/15/2023 11:49am
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.
 

Giving this a shot! First post, but read this whole thing and just trying to get some clarity. Need the bike up and running Friday, so exhausting all options:

 2020 125sx - few questions abut jetting for my race bike as I am short on time needing it this friday.

-VP T2

-Bud Racing MX High Compression Head (set to 0.0 deck height

-KTM Spark Plugs

-Wiseco Racer Elite single ring piston

-FMF Fatty

-FMF Shorty

-VForce Reeds 4

Racing at 0-2000 feet

Temps will be 40-65 degrees

I have been told that with these heads/inserts and T2 fuel, these bikes love fuel.. So, what would you recommend for jetting? 

Currently run (Pre BUD head, Vforce Reeds, and new top end/piston):

MJ-520

PJ-32.5

Needle - 43-71

Clip - 2

A/S - 1.5 out

Cut the slide? Go with Yamaha needle? Slide jet #4? JD KIT useful (aside for gasket and oring)? What size jets and clip position (all due to oxygenated fuel, lower air temps, and hi compression).

THANKS SO MUCH!

FGR01
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11/17/2023 9:24am
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.
 

thekybo wrote:
Giving this a shot! First post, but read this whole thing and just trying to get some clarity. Need the bike up and running Friday, so...

Giving this a shot! First post, but read this whole thing and just trying to get some clarity. Need the bike up and running Friday, so exhausting all options:

 2020 125sx - few questions abut jetting for my race bike as I am short on time needing it this friday.

-VP T2

-Bud Racing MX High Compression Head (set to 0.0 deck height

-KTM Spark Plugs

-Wiseco Racer Elite single ring piston

-FMF Fatty

-FMF Shorty

-VForce Reeds 4

Racing at 0-2000 feet

Temps will be 40-65 degrees

I have been told that with these heads/inserts and T2 fuel, these bikes love fuel.. So, what would you recommend for jetting? 

Currently run (Pre BUD head, Vforce Reeds, and new top end/piston):

MJ-520

PJ-32.5

Needle - 43-71

Clip - 2

A/S - 1.5 out

Cut the slide? Go with Yamaha needle? Slide jet #4? JD KIT useful (aside for gasket and oring)? What size jets and clip position (all due to oxygenated fuel, lower air temps, and hi compression).

THANKS SO MUCH!

Main - 540

Pilot - 35

Needle - 42-74, clip 2 (possibly 43-74 on clip 2 when you get down in the colder temps)

Needle Jet - S4

Slide - #5 slide from JD jetting

AS - 1.5 to 1.75

Make sure you replace the jet block gasket with the one from JD.  Make sure you set the float height correctly to 7.5 - 8.5mm

Jon_Haynes
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11/20/2023 9:57am

Jets are ordered, wish me luck. Thanks guys. just had shoulder surgery so I wont be able to test for a while.

Irwin013
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1/5/2024 12:19am
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.
 

Have a 2020 ktm 125. Ran great first couple months from new. Then i started chasing my tail with jets. And nobody could point me in the right direction. Somedays i could get it close but always had that 1/4 throttle bog and rich pilot that i couldnt shake. I couldnt get a slide as they are on back order here. So i cut mine which was easy enough. IMG 3108 0.jpeg?VersionId=q7ayvr
 

i have put all specs in listed and keen to see the results when i go for a lap on the weekend. Bike has a pc pipe and r304 shorty, tsp head and vforce4. 
 

cheers for all the info. I would of never stumbled across a setting like this otherwise. 
 

1
FGR01
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1/5/2024 5:34am
Irwin013 wrote:
Have a 2020 ktm 125. Ran great first couple months from new. Then i started chasing my tail with jets. And nobody could point me in...

Have a 2020 ktm 125. Ran great first couple months from new. Then i started chasing my tail with jets. And nobody could point me in the right direction. Somedays i could get it close but always had that 1/4 throttle bog and rich pilot that i couldnt shake. I couldnt get a slide as they are on back order here. So i cut mine which was easy enough. IMG 3108 0.jpeg?VersionId=q7ayvr
 

i have put all specs in listed and keen to see the results when i go for a lap on the weekend. Bike has a pc pipe and r304 shorty, tsp head and vforce4. 
 

cheers for all the info. I would of never stumbled across a setting like this otherwise. 
 

Assuming you are using this spec from page 1? :

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

These specs were without the extra notch on the front of the slide that you have there.   With that notch, you may need to do a 30 pilot.   Especially if it is hot summer down in Aus right now.  Just be aware of that.  What fuel, oil, and ratio are you running?

Irwin013
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1/6/2024 1:56am
Irwin013 wrote:
Have a 2020 ktm 125. Ran great first couple months from new. Then i started chasing my tail with jets. And nobody could point me in...

Have a 2020 ktm 125. Ran great first couple months from new. Then i started chasing my tail with jets. And nobody could point me in the right direction. Somedays i could get it close but always had that 1/4 throttle bog and rich pilot that i couldnt shake. I couldnt get a slide as they are on back order here. So i cut mine which was easy enough. IMG 3108 0.jpeg?VersionId=q7ayvr
 

i have put all specs in listed and keen to see the results when i go for a lap on the weekend. Bike has a pc pipe and r304 shorty, tsp head and vforce4. 
 

cheers for all the info. I would of never stumbled across a setting like this otherwise. 
 

FGR01 wrote:
Assuming you are using this spec from page 1? : MJ 510 PJ 32.5 AS 1.75 slide 5.0 from JD Jetting Needle 42-74 on the 2nd...

Assuming you are using this spec from page 1? :

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

These specs were without the extra notch on the front of the slide that you have there.   With that notch, you may need to do a 30 pilot.   Especially if it is hot summer down in Aus right now.  Just be aware of that.  What fuel, oil, and ratio are you running?

Yer following specs from page 1. And i have put. 30 in the pilot for the notch and it is also between 30-40 degrees most of the time when im riding atm. Running unleaded 98 with motorex 2t oil @40:1

FGR01
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1/6/2024 7:27pm
Irwin013 wrote:
Have a 2020 ktm 125. Ran great first couple months from new. Then i started chasing my tail with jets. And nobody could point me in...

Have a 2020 ktm 125. Ran great first couple months from new. Then i started chasing my tail with jets. And nobody could point me in the right direction. Somedays i could get it close but always had that 1/4 throttle bog and rich pilot that i couldnt shake. I couldnt get a slide as they are on back order here. So i cut mine which was easy enough. IMG 3108 0.jpeg?VersionId=q7ayvr
 

i have put all specs in listed and keen to see the results when i go for a lap on the weekend. Bike has a pc pipe and r304 shorty, tsp head and vforce4. 
 

cheers for all the info. I would of never stumbled across a setting like this otherwise. 
 

FGR01 wrote:
Assuming you are using this spec from page 1? : MJ 510 PJ 32.5 AS 1.75 slide 5.0 from JD Jetting Needle 42-74 on the 2nd...

Assuming you are using this spec from page 1? :

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

These specs were without the extra notch on the front of the slide that you have there.   With that notch, you may need to do a 30 pilot.   Especially if it is hot summer down in Aus right now.  Just be aware of that.  What fuel, oil, and ratio are you running?

Irwin013 wrote:
Yer following specs from page 1. And i have put. 30 in the pilot for the notch and it is also between 30-40 degrees most of...

Yer following specs from page 1. And i have put. 30 in the pilot for the notch and it is also between 30-40 degrees most of the time when im riding atm. Running unleaded 98 with motorex 2t oil @40:1

Let us know how it runs.

1/26/2024 12:53pm Edited Date/Time 1/26/2024 1:00pm

2022 250sx

FMF pipe and silencer 

MJ 490
PJ 32.5
AS 1.75
slide 5.75 from JD Jetting
Needle 43-75 on the 2nd clip 
Needle jet S4 (KTM part #55431021400)
PV 2.25 turns in from all the way out.
Fuel mix 36:1 Motorex

2:1 91 pump gas/100LL av gas

Bike is slightly lean its seems on the top and a high idle. but the air has been cold in AZ. 500 Main now installed and will try a 35 PJ in it this weekend. I think the recommended settings would be prefect during the summer

Overall the bike is way more crisp from the mess it was stock lol

AJ565
Posts
2096
Joined
3/12/2012
Location
San Antonio, TX US
1/26/2024 6:31pm
2022 250sx FMF pipe and silencer  MJ 490 PJ 32.5 AS 1.75 slide 5.75 from JD Jetting Needle 43-75 on the 2nd clip  Needle jet S4...

2022 250sx

FMF pipe and silencer 

MJ 490
PJ 32.5
AS 1.75
slide 5.75 from JD Jetting
Needle 43-75 on the 2nd clip 
Needle jet S4 (KTM part #55431021400)
PV 2.25 turns in from all the way out.
Fuel mix 36:1 Motorex

2:1 91 pump gas/100LL av gas

Bike is slightly lean its seems on the top and a high idle. but the air has been cold in AZ. 500 Main now installed and will try a 35 PJ in it this weekend. I think the recommended settings would be prefect during the summer

Overall the bike is way more crisp from the mess it was stock lol

Back the power valve out 1 turn and mix the fuel to 50:1 with the 500 main. When the temps are below 40 I have to go to a 35 pilot and the 3rd clip on the needle especially with ave gas or 50/50 T2/ethanol free pump. I can’t comment on the idle as I have mine set to stall if I let it try to idle by itself. 

FGR01
Posts
5194
Joined
10/1/2006
Location
AZ US
Fantasy
947th
1/26/2024 7:18pm
2022 250sx FMF pipe and silencer  MJ 490 PJ 32.5 AS 1.75 slide 5.75 from JD Jetting Needle 43-75 on the 2nd clip  Needle jet S4...

2022 250sx

FMF pipe and silencer 

MJ 490
PJ 32.5
AS 1.75
slide 5.75 from JD Jetting
Needle 43-75 on the 2nd clip 
Needle jet S4 (KTM part #55431021400)
PV 2.25 turns in from all the way out.
Fuel mix 36:1 Motorex

2:1 91 pump gas/100LL av gas

Bike is slightly lean its seems on the top and a high idle. but the air has been cold in AZ. 500 Main now installed and will try a 35 PJ in it this weekend. I think the recommended settings would be prefect during the summer

Overall the bike is way more crisp from the mess it was stock lol

I'm riding AZ also and all my settings are the same as yours except I am at 1.25 - 1.50 on the PV as AJ said.  My bike is a 300 now and I am on a 35 pilot.   I was on a 37.5 when the temps dropped when it was a 250.   I run straight Avgas at 38:1.

 

Irwin013
Posts
3
Joined
1/5/2024
Location
St george, QLD AU
2/5/2024 1:35pm
FGR01 wrote:
Assuming you are using this spec from page 1? : MJ 510 PJ 32.5 AS 1.75 slide 5.0 from JD Jetting Needle 42-74 on the 2nd...

Assuming you are using this spec from page 1? :

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

These specs were without the extra notch on the front of the slide that you have there.   With that notch, you may need to do a 30 pilot.   Especially if it is hot summer down in Aus right now.  Just be aware of that.  What fuel, oil, and ratio are you running?

Irwin013 wrote:
Yer following specs from page 1. And i have put. 30 in the pilot for the notch and it is also between 30-40 degrees most of...

Yer following specs from page 1. And i have put. 30 in the pilot for the notch and it is also between 30-40 degrees most of the time when im riding atm. Running unleaded 98 with motorex 2t oil @40:1

FGR01 wrote:

Let us know how it runs.

Took bike out couple of weeks ago and was getting a bog in corners and when snapping the throttle on. apon reading abit more through here seen someone with similar issue where pilot was to lean. I have since changed to 37.5 pilot and 520 main. I took bike out again on the weekend and all i can say is wow. What a differance, bike has never been so crisp and responsive through the entire throttle range, no longer loads up when idling. 

Thanks Heaps 

1
FGR01
Posts
5194
Joined
10/1/2006
Location
AZ US
Fantasy
947th
2/5/2024 7:23pm
Irwin013 wrote:
Took bike out couple of weeks ago and was getting a bog in corners and when snapping the throttle on. apon reading abit more through here...

Took bike out couple of weeks ago and was getting a bog in corners and when snapping the throttle on. apon reading abit more through here seen someone with similar issue where pilot was to lean. I have since changed to 37.5 pilot and 520 main. I took bike out again on the weekend and all i can say is wow. What a differance, bike has never been so crisp and responsive through the entire throttle range, no longer loads up when idling. 

Thanks Heaps 

That's great.  Glad to hear it's rippin'....

Lasse
Posts
529
Joined
11/5/2015
Location
DK
Fantasy
3163rd
2/17/2024 5:31am

GasGas MC250 2022

HGS silencer and pipe

VHM 12 set piston and insert of 22.60 cc

Main jet 500
Pilot jet 32.5
Slide 5.75 (Filed by hand)
Needle 43-75 (KTM part #55431134400)
Clip position #3 (mid)
Needle jet S4 (KTM part #55431021400)
Air screw 1.5-2.0
Fuel 32:1

Pulls strong on top, but at part throttle and mainly when closing the slide I will hear a hiss/quack/wha. I was thinking a lean condition part throttle so raised the needle from 2 from top to third. Seemed to help, will try raising it a notch more next time I am out.

Caveat, fuel is Octane 100 that has been sitting for 4 months.

 

FGR01
Posts
5194
Joined
10/1/2006
Location
AZ US
Fantasy
947th
2/18/2024 4:30pm
Lasse wrote:
GasGas MC250 2022 HGS silencer and pipe VHM 12 set piston and insert of 22.60 cc Main jet 500 Pilot jet 32.5 Slide 5.75 (Filed by...

GasGas MC250 2022

HGS silencer and pipe

VHM 12 set piston and insert of 22.60 cc

Main jet 500
Pilot jet 32.5
Slide 5.75 (Filed by hand)
Needle 43-75 (KTM part #55431134400)
Clip position #3 (mid)
Needle jet S4 (KTM part #55431021400)
Air screw 1.5-2.0
Fuel 32:1

Pulls strong on top, but at part throttle and mainly when closing the slide I will hear a hiss/quack/wha. I was thinking a lean condition part throttle so raised the needle from 2 from top to third. Seemed to help, will try raising it a notch more next time I am out.

Caveat, fuel is Octane 100 that has been sitting for 4 months.

 

What is the Temperature and elevation?  On my MC250 I was mostly same jetting as you...  but running 38:1 and and 43-75 on C2.   I was using a 37.5 pilot with this when it was cold out.   I'd try going to 35 or 37.5 if I was you.

Hcallz5
Posts
2902
Joined
8/20/2013
Location
UT US
2/20/2024 7:32pm Edited Date/Time 2/20/2024 7:44pm

Has anyone used the TSP offset woodruff key at all? I ordered one, going to see how it performs. Hopefully a little more midrange on the 150 for some enduro stuff.  Edit: Sorry i guess that's not jetting technically Grinning

Lasse
Posts
529
Joined
11/5/2015
Location
DK
Fantasy
3163rd
2/20/2024 9:18pm
Lasse wrote:
GasGas MC250 2022 HGS silencer and pipe VHM 12 set piston and insert of 22.60 cc Main jet 500 Pilot jet 32.5 Slide 5.75 (Filed by...

GasGas MC250 2022

HGS silencer and pipe

VHM 12 set piston and insert of 22.60 cc

Main jet 500
Pilot jet 32.5
Slide 5.75 (Filed by hand)
Needle 43-75 (KTM part #55431134400)
Clip position #3 (mid)
Needle jet S4 (KTM part #55431021400)
Air screw 1.5-2.0
Fuel 32:1

Pulls strong on top, but at part throttle and mainly when closing the slide I will hear a hiss/quack/wha. I was thinking a lean condition part throttle so raised the needle from 2 from top to third. Seemed to help, will try raising it a notch more next time I am out.

Caveat, fuel is Octane 100 that has been sitting for 4 months.

 

FGR01 wrote:
What is the Temperature and elevation?  On my MC250 I was mostly same jetting as you...  but running 38:1 and and 43-75 on C2.   I was...

What is the Temperature and elevation?  On my MC250 I was mostly same jetting as you...  but running 38:1 and and 43-75 on C2.   I was using a 37.5 pilot with this when it was cold out.   I'd try going to 35 or 37.5 if I was you.

Thanks for getting back to me. I’m at sealevel, on that day it was 8 deg C. I’ll get an 37,5 as well Smile  

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