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

Jayklash
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8/27/2019 2:34pm
Jayklash wrote:
I am trying to source one direct from mikuni as it is much cheaper. But they said they need the exact dimensions of the slide do...
I am trying to source one direct from mikuni as it is much cheaper. But they said they need the exact dimensions of the slide do you happen to know what they are please?
digger wrote:
Why do they need the exact dimension? There are 2 versions of that tmx-x , but the Oem KTM Mikuni is able to use both versions...
Why do they need the exact dimension? There are 2 versions of that tmx-x , but the Oem KTM Mikuni is able to use both versions. The Mikuni equipped TMX-x with TPI slides are a slightly different version. They have a semi filled port to allow the tpi to contact the slide, but both are the same dimension wise, with the exception on the filled port.
They said they have different variations of that slide and the only way to get the correct one would be to know the exact dimensions. I gave them the KTM code but they said their codes are completely different as ktm use there own codes
jwolfman317
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8/27/2019 2:49pm
digger wrote:
The best 125/150 jetting setup that I have come up with is: 42-74 needle start out in the #2 clip position https://www.motosport.com/oem-parts/part-number/284-14116-h4-00?mmysource=yamaha;yz125;2019&partgroup=carburetor S-4 needle jet #5-slide...
The best 125/150 jetting setup that I have come up with is:

42-74 needle start out in the #2 clip position https://www.motosport.com/oem-parts/part-number/284-14116-h4-00?mmysour…

S-4 needle jet

#5-slide, it's a must have item. IMO,


#5.5-#6 slides are to lean for the small bore bikes. You can either cut your #4 oem yourself, or you can purchase one from JD jetting.
https://jdjetting.com/product/jdmk02-mikuni-tmx-ktm-husq-carburetor-sli…

Main. 490

32.5--pilot
if you notch the front side of the slide, you will need a 30 pilot

You will also more than likely need a jet block gasket, as the oem ones deform over a very short amount of time.

https://jdjetting.com/product/jdmk05-mikuni-tmx-jet-block-kit/

air screw at 1.5 turns out to begin with.
If I was to use these exact specs but with these exceptions:

S-7 needle jet
42-75 needle , 3rd position

what would you expect the results to be? I was running that originally but it was too lean below half throttle and I’m still confused by it. The S-4 needle jet is .0006” smaller than the S-7, yet the 42-74 needle is only .0004” smaller than the 42-75, so it seems like it would flow less fuel, but it is definitely richer with your settings below half throttle.
digger
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8/28/2019 5:50am
Jayklash wrote:
I am trying to source one direct from mikuni as it is much cheaper. But they said they need the exact dimensions of the slide do...
I am trying to source one direct from mikuni as it is much cheaper. But they said they need the exact dimensions of the slide do you happen to know what they are please?
Here is the Suzuki part# for a #5 Mikuni slide, If you can't source one independently.

https://www.partzilla.com/product/suzuki/13551-36F50?ref=cf3fd997ae8f8e…
digger
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8/28/2019 6:00am
If I was to use these exact specs but with these exceptions: S-7 needle jet 42-75 needle , 3rd position what would you expect the results...
If I was to use these exact specs but with these exceptions:

S-7 needle jet
42-75 needle , 3rd position

what would you expect the results to be? I was running that originally but it was too lean below half throttle and I’m still confused by it. The S-4 needle jet is .0006” smaller than the S-7, yet the 42-74 needle is only .0004” smaller than the 42-75, so it seems like it would flow less fuel, but it is definitely richer with your settings below half throttle.
There is a bunch of overlap between those 2 tuning devises, but i would suspect that the needle jet would play a stronger roll than the leaner diameter needle. I never tried that route on the current KTM's.

The Shop

jpatz319
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9/3/2019 8:43am
AJ565 wrote:
I ride mine like a 125 too lol. 40:1 is more oil so it would be leaner fuel mix. I think so, digger posted in another...
I ride mine like a 125 too lol.

40:1 is more oil so it would be leaner fuel mix. I think so, digger posted in another thread 1.5mm deeper and wider on the cut to turn a 4.0 into a 5.5. I have one that I cut that next time I go ride I'll swap into it and see what happens and if I have to change any other jetting. I have a 500 MJ that I need to try also.
I rode this weekend with some updated settings:

50/50 Pump Gas/C12
MJ 490
PJ 32.5
AS 2.0 turns out
Needle jet S4
Needle 42-75 on the 3rd clip
Slide 5.50
PV 1.5 turns in from all the way out
Fuel mix 60:1 with motorex oil

She ran get and is no longer running lean
opyguy
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9/3/2019 9:23am
posted this elsewhere, but I ran the Suzuki 17-62 needle in the Mikuni, 37.5 pilot and 450 main, bike now runs ridiculously good. I believe DEMI suggested the needle.
Dexter
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Limoges FR
9/4/2019 1:22am
Stock slide ?
opyguy
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9/4/2019 8:07am
5.75 slide
AJ565
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9/4/2019 8:59am
AJ565 wrote:
I ride mine like a 125 too lol. 40:1 is more oil so it would be leaner fuel mix. I think so, digger posted in another...
I ride mine like a 125 too lol.

40:1 is more oil so it would be leaner fuel mix. I think so, digger posted in another thread 1.5mm deeper and wider on the cut to turn a 4.0 into a 5.5. I have one that I cut that next time I go ride I'll swap into it and see what happens and if I have to change any other jetting. I have a 500 MJ that I need to try also.
jpatz319 wrote:
I rode this weekend with some updated settings: 50/50 Pump Gas/C12 MJ 490 PJ 32.5 AS 2.0 turns out Needle jet S4 Needle 42-75 on the...
I rode this weekend with some updated settings:

50/50 Pump Gas/C12
MJ 490
PJ 32.5
AS 2.0 turns out
Needle jet S4
Needle 42-75 on the 3rd clip
Slide 5.50
PV 1.5 turns in from all the way out
Fuel mix 60:1 with motorex oil

She ran get and is no longer running lean
I'll give it a try this weekend with a 500 MJ (oxygenated fuel) and the 5.5 slide and post up my results.
AJ565
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9/8/2019 5:03pm
jpatz319 wrote:
I rode this weekend with some updated settings: 50/50 Pump Gas/C12 MJ 490 PJ 32.5 AS 2.0 turns out Needle jet S4 Needle 42-75 on the...
I rode this weekend with some updated settings:

50/50 Pump Gas/C12
MJ 490
PJ 32.5
AS 2.0 turns out
Needle jet S4
Needle 42-75 on the 3rd clip
Slide 5.50
PV 1.5 turns in from all the way out
Fuel mix 60:1 with motorex oil

She ran get and is no longer running lean
Ok just got home. Swapped out the slide and MJ and it was a very good setup. I have a bit more high RPM pull and doesn’t fall off as much or soon. Temps today were in the high 90’s. I’m going to leave the jetting in and also update the first post with this info for those that are to lazy to read all the posts.

u4.4 oxygenated race fuel
MJ 500
PJ 35
AS 1.5 turns out
Needle jet S4
Needle 42-75 on the 3rd clip
Slide 5.5
PV 1.75 turns in from all the way out
Fuel mix 44:1
Jayklash
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9/27/2019 3:30am
digger wrote:
The best 125/150 jetting setup that I have come up with is: 42-74 needle start out in the #2 clip position https://www.motosport.com/oem-parts/part-number/284-14116-h4-00?mmysource=yamaha;yz125;2019&partgroup=carburetor S-4 needle jet #5-slide...
The best 125/150 jetting setup that I have come up with is:

42-74 needle start out in the #2 clip position https://www.motosport.com/oem-parts/part-number/284-14116-h4-00?mmysour…

S-4 needle jet

#5-slide, it's a must have item. IMO,


#5.5-#6 slides are to lean for the small bore bikes. You can either cut your #4 oem yourself, or you can purchase one from JD jetting.
https://jdjetting.com/product/jdmk02-mikuni-tmx-ktm-husq-carburetor-sli…

Main. 490

32.5--pilot
if you notch the front side of the slide, you will need a 30 pilot

You will also more than likely need a jet block gasket, as the oem ones deform over a very short amount of time.

https://jdjetting.com/product/jdmk05-mikuni-tmx-jet-block-kit/

air screw at 1.5 turns out to begin with.
Does the bike come stock with the S4 needle jet or an S1 needle jet?
Jayklash
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10/11/2019 7:16am
digger wrote:
The best 125/150 jetting setup that I have come up with is: 42-74 needle start out in the #2 clip position https://www.motosport.com/oem-parts/part-number/284-14116-h4-00?mmysource=yamaha;yz125;2019&partgroup=carburetor S-4 needle jet #5-slide...
The best 125/150 jetting setup that I have come up with is:

42-74 needle start out in the #2 clip position https://www.motosport.com/oem-parts/part-number/284-14116-h4-00?mmysour…

S-4 needle jet

#5-slide, it's a must have item. IMO,


#5.5-#6 slides are to lean for the small bore bikes. You can either cut your #4 oem yourself, or you can purchase one from JD jetting.
https://jdjetting.com/product/jdmk02-mikuni-tmx-ktm-husq-carburetor-sli…

Main. 490

32.5--pilot
if you notch the front side of the slide, you will need a 30 pilot

You will also more than likely need a jet block gasket, as the oem ones deform over a very short amount of time.

https://jdjetting.com/product/jdmk05-mikuni-tmx-jet-block-kit/

air screw at 1.5 turns out to begin with.
Ok so second attempt at removing the needle jet. This time it came out very easy now that I was pushing it out from the right end😪 I have put the carb back on the bike and have given it a quick start but haven't ran it yet as I can't where I live. You said to start out on the second clip position on the needle which I have done. Do you sometimes find the need to move up or down a notch ?
seth505
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SD, CA US
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10/11/2019 11:09am
FYI- after not dealing with it for a long time I finally replaced the block gasket in the stock Mikuni earlier this year and it definitely helped clean things up. Very happy from replacing that small dollar item.
2
AJ565
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San Antonio, TX US
10/11/2019 1:55pm
Jayklash wrote:
Ok so second attempt at removing the needle jet. This time it came out very easy now that I was pushing it out from the right...
Ok so second attempt at removing the needle jet. This time it came out very easy now that I was pushing it out from the right end😪 I have put the carb back on the bike and have given it a quick start but haven't ran it yet as I can't where I live. You said to start out on the second clip position on the needle which I have done. Do you sometimes find the need to move up or down a notch ?
Thats going to depend on temps and elevation. Second position is a good starting point. In my 250 I had to go to the 3rd clip to richen things up a little bit. Cooler air will require you to go richer, hot air will make you need leaner.
Jayklash
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10/11/2019 2:01pm
Jayklash wrote:
Ok so second attempt at removing the needle jet. This time it came out very easy now that I was pushing it out from the right...
Ok so second attempt at removing the needle jet. This time it came out very easy now that I was pushing it out from the right end😪 I have put the carb back on the bike and have given it a quick start but haven't ran it yet as I can't where I live. You said to start out on the second clip position on the needle which I have done. Do you sometimes find the need to move up or down a notch ?
AJ565 wrote:
Thats going to depend on temps and elevation. Second position is a good starting point. In my 250 I had to go to the 3rd clip...
Thats going to depend on temps and elevation. Second position is a good starting point. In my 250 I had to go to the 3rd clip to richen things up a little bit. Cooler air will require you to go richer, hot air will make you need leaner.
I am in the UK and temperatures are currently around 13'c so might need to go on the 3rd clip
digger
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10/11/2019 8:39pm
Jayklash wrote:
Ok so second attempt at removing the needle jet. This time it came out very easy now that I was pushing it out from the right...
Ok so second attempt at removing the needle jet. This time it came out very easy now that I was pushing it out from the right end😪 I have put the carb back on the bike and have given it a quick start but haven't ran it yet as I can't where I live. You said to start out on the second clip position on the needle which I have done. Do you sometimes find the need to move up or down a notch ?
AJ565 wrote:
Thats going to depend on temps and elevation. Second position is a good starting point. In my 250 I had to go to the 3rd clip...
Thats going to depend on temps and elevation. Second position is a good starting point. In my 250 I had to go to the 3rd clip to richen things up a little bit. Cooler air will require you to go richer, hot air will make you need leaner.
Jayklash wrote:
I am in the UK and temperatures are currently around 13'c so might need to go on the 3rd clip
Possibly, but start out in the 2nd clip position. Those temps are similar to what we have in NY right now and the bike I have set up now are only requiring small air screw adjustments.
Jayklash
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10/12/2019 7:00am
AJ565 wrote:
Thats going to depend on temps and elevation. Second position is a good starting point. In my 250 I had to go to the 3rd clip...
Thats going to depend on temps and elevation. Second position is a good starting point. In my 250 I had to go to the 3rd clip to richen things up a little bit. Cooler air will require you to go richer, hot air will make you need leaner.
Jayklash wrote:
I am in the UK and temperatures are currently around 13'c so might need to go on the 3rd clip
digger wrote:
Possibly, but start out in the 2nd clip position. Those temps are similar to what we have in NY right now and the bike I have...
Possibly, but start out in the 2nd clip position. Those temps are similar to what we have in NY right now and the bike I have set up now are only requiring small air screw adjustments.
So I just tested the bike for the first time and something isn't quite right. It bogs when I pull the throttle back quickly any ideas? I didn't change the float height could it need a bigger pilot?
Jayklash
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10/12/2019 8:22am
Can anyone help? Need to get this bike dialled this weekend
digger
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10/12/2019 6:13pm
Yes, try a bigger pilot.
Jayklash
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10/13/2019 12:53am
digger wrote:
Yes, try a bigger pilot.
Ok so I bumped the pilot jet up to 35 and went in half a turn on the air screw. Gave the bike a quick rev on the stand as I cannot run the bike properly where I live in a block of flats 🙄. Hard to tell if the bog has completely gone away as the bike was nowhere near warm but definitely sounded better. Might bump the pilot up to 37.5 to be safe. what do you think?
digger
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10/13/2019 4:40pm
Jayklash wrote:
Ok so I bumped the pilot jet up to 35 and went in half a turn on the air screw. Gave the bike a quick rev...
Ok so I bumped the pilot jet up to 35 and went in half a turn on the air screw. Gave the bike a quick rev on the stand as I cannot run the bike properly where I live in a block of flats 🙄. Hard to tell if the bog has completely gone away as the bike was nowhere near warm but definitely sounded better. Might bump the pilot up to 37.5 to be safe. what do you think?
Try it with the 35 pilot first.
Jayklash
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10/14/2019 1:53am
Ok I'll give it a try.
Bruce372
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10/16/2019 11:16am
digger wrote:
The best 125/150 jetting setup that I have come up with is: 42-74 needle start out in the #2 clip position https://www.motosport.com/oem-parts/part-number/284-14116-h4-00?mmysource=yamaha;yz125;2019&partgroup=carburetor S-4 needle jet #5-slide...
The best 125/150 jetting setup that I have come up with is:

42-74 needle start out in the #2 clip position https://www.motosport.com/oem-parts/part-number/284-14116-h4-00?mmysour…

S-4 needle jet

#5-slide, it's a must have item. IMO,


#5.5-#6 slides are to lean for the small bore bikes. You can either cut your #4 oem yourself, or you can purchase one from JD jetting.
https://jdjetting.com/product/jdmk02-mikuni-tmx-ktm-husq-carburetor-sli…

Main. 490

32.5--pilot
if you notch the front side of the slide, you will need a 30 pilot

You will also more than likely need a jet block gasket, as the oem ones deform over a very short amount of time.

https://jdjetting.com/product/jdmk05-mikuni-tmx-jet-block-kit/

air screw at 1.5 turns out to begin with.
If I was to use these exact specs but with these exceptions: S-7 needle jet 42-75 needle , 3rd position what would you expect the results...
If I was to use these exact specs but with these exceptions:

S-7 needle jet
42-75 needle , 3rd position

what would you expect the results to be? I was running that originally but it was too lean below half throttle and I’m still confused by it. The S-4 needle jet is .0006” smaller than the S-7, yet the 42-74 needle is only .0004” smaller than the 42-75, so it seems like it would flow less fuel, but it is definitely richer with your settings below half throttle.
Guys-

I am a little confused on this thread.... are these specs for the 125, 150 or 250?

thanks!

I am looking for a jetting spec for the mikuni on the KTM150 2018. T2 fuel (40:1)

thanks, Bruce
Jayklash
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10/16/2019 11:22am
The specs are for KTM SX 150 17 +. I also have the 2018 model. Does the fuel you use make a difference to jetting? I am in the UK and use shell v Power which is 99 octane
AJ565
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10/16/2019 12:26pm Edited Date/Time 10/16/2019 12:28pm
Bruce372 wrote:
Guys- I am a little confused on this thread.... are these specs for the 125, 150 or 250? thanks! I am looking for a jetting spec...
Guys-

I am a little confused on this thread.... are these specs for the 125, 150 or 250?

thanks!

I am looking for a jetting spec for the mikuni on the KTM150 2018. T2 fuel (40:1)

thanks, Bruce
First page has specs. for both. The part you quoted was for a 125/150. With T2 being oxygenated you may need to richen up the main and the pilot.
AJ565
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10/16/2019 12:30pm Edited Date/Time 10/16/2019 12:31pm
Jayklash wrote:
The specs are for KTM SX 150 17 +. I also have the 2018 model. Does the fuel you use make a difference to jetting? I...
The specs are for KTM SX 150 17 +. I also have the 2018 model. Does the fuel you use make a difference to jetting? I am in the UK and use shell v Power which is 99 octane
Yes it does. T2 like he was asking about and u4.4 which is what I run both need bigger main and pilot jets because of the oxygen content in the fuel. Pump gas or non oxygenated race fuel like C12 you'll be fine with the jetting digger is telling you to run.
Lowlander
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10/16/2019 9:53pm
Jayklash wrote:
The specs are for KTM SX 150 17 +. I also have the 2018 model. Does the fuel you use make a difference to jetting? I...
The specs are for KTM SX 150 17 +. I also have the 2018 model. Does the fuel you use make a difference to jetting? I am in the UK and use shell v Power which is 99 octane
Shell power 99 is about the same as 93-95 in the states.

Different scales for knock. RON vs AKI (RON+MON/2)
Jayklash
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10/20/2019 9:34am
Jayklash wrote:
Ok so I bumped the pilot jet up to 35 and went in half a turn on the air screw. Gave the bike a quick rev...
Ok so I bumped the pilot jet up to 35 and went in half a turn on the air screw. Gave the bike a quick rev on the stand as I cannot run the bike properly where I live in a block of flats 🙄. Hard to tell if the bog has completely gone away as the bike was nowhere near warm but definitely sounded better. Might bump the pilot up to 37.5 to be safe. what do you think?
digger wrote:
Try it with the 35 pilot first.
So I took the bike to the track today for the first time I'm since rejecting to your specs. As I said previously 32.5 pilot was too small and would bog when I pull the throttle quickly. I went straight to the 37.5 pilot instead of the 35 as I didn't really want to have to reject at the track with the bike all dirty if the pilot was still a bit lean. So I went two turns in on the air screw with 37.5 and the bike ran crisp and clean. The jetting was spot on throughout the entire range. Thanks again. another bike jetted perfectly 👊🏼
digger
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10/20/2019 8:50pm
Jayklash wrote:
So I took the bike to the track today for the first time I'm since rejecting to your specs. As I said previously 32.5 pilot was...
So I took the bike to the track today for the first time I'm since rejecting to your specs. As I said previously 32.5 pilot was too small and would bog when I pull the throttle quickly. I went straight to the 37.5 pilot instead of the 35 as I didn't really want to have to reject at the track with the bike all dirty if the pilot was still a bit lean. So I went two turns in on the air screw with 37.5 and the bike ran crisp and clean. The jetting was spot on throughout the entire range. Thanks again. another bike jetted perfectly 👊🏼
With the 37.5 pilot, is that with the front side of the slide notched ? Can you list your current carb specs ?
Jayklash
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10/20/2019 11:48pm
Jayklash wrote:
So I took the bike to the track today for the first time I'm since rejecting to your specs. As I said previously 32.5 pilot was...
So I took the bike to the track today for the first time I'm since rejecting to your specs. As I said previously 32.5 pilot was too small and would bog when I pull the throttle quickly. I went straight to the 37.5 pilot instead of the 35 as I didn't really want to have to reject at the track with the bike all dirty if the pilot was still a bit lean. So I went two turns in on the air screw with 37.5 and the bike ran crisp and clean. The jetting was spot on throughout the entire range. Thanks again. another bike jetted perfectly 👊🏼
digger wrote:
With the 37.5 pilot, is that with the front side of the slide notched ? Can you list your current carb specs ?
42-74 needle 2nd clip
S4 needle jet
Slide 5.0
MJ: 490
PJ: 37.5
Air screw 2 turns out

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