KTM 125sx Keihin 38mm Jetting

Bart149
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Bart149
I need help. Hopefully Digger reads this. We are currently running two 2019 KTM 125SX's for my son. One is a practice bike. The other is the race bike. I am using the the jetting for the Mikuni's found on this forum. It works well for the Mikuni carb. But it is still not the best. Anyway I am modifying the race bike right now and bought a Keihin 38mm from JD jetting(only reason I purchased from JD is it was the same price as other places and you get there jetting kit). After taking the carb apart I noticed it comes with a 6.5 slide. The stock Keihin on the 2016 KTMs used to have a 7 slide. What one would be better for a modified 125? Should I us there jetting kit or just do my own thing? What are there mystery needle's? I have not used the carb yet so I can return it.
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digger
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digger 8/3/2022 10:42am
8/3/2022 10:42am
Bart149 wrote:
I need help. Hopefully Digger reads this. We are currently running two 2019 KTM 125SX's for my son. One is a practice bike. The other is...
I need help. Hopefully Digger reads this. We are currently running two 2019 KTM 125SX's for my son. One is a practice bike. The other is the race bike. I am using the the jetting for the Mikuni's found on this forum. It works well for the Mikuni carb. But it is still not the best. Anyway I am modifying the race bike right now and bought a Keihin 38mm from JD jetting(only reason I purchased from JD is it was the same price as other places and you get there jetting kit). After taking the carb apart I noticed it comes with a 6.5 slide. The stock Keihin on the 2016 KTMs used to have a 7 slide. What one would be better for a modified 125? Should I us there jetting kit or just do my own thing? What are there mystery needle's? I have not used the carb yet so I can return it.
That 6.5 slide should be fine. I wouldn't have a problem using it. As far as the JD jetting kit goes, it depends on which kit you got. He,JD, sells an optional needle for small bore bikes that works pretty good. It almost seems like a copy of an 00' Honda cr250 optional needle,685/289. The standard needle, I'm not so sure about. If you've gone this far, you might as well buy CCL and a CCM single taper needles. I know for sure they work.

Summer jetting; CCM in #2 or 3clip, 48 pilot, 178/180 main. Set the air screw at 1.5 and start from there.

Fall jetting: CCL in 2/3, 50 pilot, 182--185

CCM-- https://www.jetsrus.com/individual_parts/017-465_su.html

CCL- https://www.jetsrus.com/individual_parts/017-464_su.html

1
Bruce372
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Bruce372 8/3/2022 12:13pm
8/3/2022 12:13pm
I've used keihin carbs on multiple 125s and 150s, I would stay away from the straight taper keihin needles, I always had detonation issues.

The KTM Oem needles will work, NOZI or NIEF etc. The only issue is getting the needle diameter matched up perfectly with the pilot and slide.

Search dynodan on here, he posted the settings.

I have the Sam's carb on ktm 125 and 150 right now we are running the stic insert though.
Bart149
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Bart149 8/3/2022 12:15pm
8/3/2022 12:15pm
I'm not sure what the needles are it's just a kit that says 125/150cc that comes with the carb. There setting seam a little on the rich side. Since I am going for max horsepower I think I will try the CCL and CCM needles. Thank You for your help.
Bruce372
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Bruce372 8/3/2022 12:17pm
8/3/2022 12:17pm
2016 ktm125 is similar engine to 2019, so use that jetting starting point. I think it's 50p, 175 main and NOZI.

We also run the 2016 carb manifold and hose clamp that seats the keihin carb properly

The Shop

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Bart149
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Bart149 8/3/2022 12:20pm
8/3/2022 12:20pm
Do you Know what slide to use with the CCM and CCL needles? Are the CC needles straight taper?
Bruce372
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Bruce372 8/3/2022 12:35pm
8/3/2022 12:35pm
Bart149 wrote:
Do you Know what slide to use with the CCM and CCL needles? Are the CC needles straight taper?
I think those needles are straight taper.

6.5 and 7 slide are quite similar, slide overlaps with pilot and needle diameter so that is a tuning option
Bart149
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Bart149 8/3/2022 1:21pm
8/3/2022 1:21pm
Bruce, I read in one of your other posts that you run the FMF pipe and silencer. Have you tried the PC pipe and silencer? I spoke to a guy at XPR motorsports, they have a build on you tube and he said the HGS made the best power on the dyno and the only other combo that made good power was a Pro circuit pipe with a FMF silencer. I would go with the HGS but they are harder to get.
Bruce372
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Bruce372 8/3/2022 2:21pm
8/3/2022 2:21pm
Bart149 wrote:
Bruce, I read in one of your other posts that you run the FMF pipe and silencer. Have you tried the PC pipe and silencer? I...
Bruce, I read in one of your other posts that you run the FMF pipe and silencer. Have you tried the PC pipe and silencer? I spoke to a guy at XPR motorsports, they have a build on you tube and he said the HGS made the best power on the dyno and the only other combo that made good power was a Pro circuit pipe with a FMF silencer. I would go with the HGS but they are harder to get.
On the 2018 150, fmf main pipe makes a small improvement. But all silencers apart from pc shorty are worse than stock. The 150 likes a big opening at the end of the silencer! On 150, HGS we dynoed made less power apart from maybe 0.5hp over stock for about 500rpm at peak... where no one rides!

Not sure about 125, but we have gone back to stock on everything. I am over aftermarket stuff, I've got a box full of cracked fmf pipes.

We have 2018 tc125, and sx150. Stock everything, apart from oem 2016 carb manifold and a stic fitted keihin carb. The bikes really rip.
Even the stock reeds are fine IMO. One thing I wanted to do was get new head inserts made to reduce the squish gap slightly, but the guy fell through. So even head and cylinder is stock.

I did follow threads here and dialed in the mikuni on thr 150 really good, nice crisp and clean carburetion, very good for trial riding. For mx, imo the stic works best. On the 125, I managed to dial it well for pump gas with supplied jets, but it doesn't run on oxy race fuel.

These bikes are so good, and once setup are reliable. I am over all the aftermarket stuff, it rarely fits right or runs right.
opyguy
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opyguy 8/3/2022 5:40pm
8/3/2022 5:40pm
Bart149 wrote:
I need help. Hopefully Digger reads this. We are currently running two 2019 KTM 125SX's for my son. One is a practice bike. The other is...
I need help. Hopefully Digger reads this. We are currently running two 2019 KTM 125SX's for my son. One is a practice bike. The other is the race bike. I am using the the jetting for the Mikuni's found on this forum. It works well for the Mikuni carb. But it is still not the best. Anyway I am modifying the race bike right now and bought a Keihin 38mm from JD jetting(only reason I purchased from JD is it was the same price as other places and you get there jetting kit). After taking the carb apart I noticed it comes with a 6.5 slide. The stock Keihin on the 2016 KTMs used to have a 7 slide. What one would be better for a modified 125? Should I us there jetting kit or just do my own thing? What are there mystery needle's? I have not used the carb yet so I can return it.
digger wrote:
That 6.5 slide should be fine. I wouldn't have a problem using it. As far as the JD jetting kit goes, it depends on which kit...
That 6.5 slide should be fine. I wouldn't have a problem using it. As far as the JD jetting kit goes, it depends on which kit you got. He,JD, sells an optional needle for small bore bikes that works pretty good. It almost seems like a copy of an 00' Honda cr250 optional needle,685/289. The standard needle, I'm not so sure about. If you've gone this far, you might as well buy CCL and a CCM single taper needles. I know for sure they work.

Summer jetting; CCM in #2 or 3clip, 48 pilot, 178/180 main. Set the air screw at 1.5 and start from there.

Fall jetting: CCL in 2/3, 50 pilot, 182--185

CCM-- https://www.jetsrus.com/individual_parts/017-465_su.html

CCL- https://www.jetsrus.com/individual_parts/017-464_su.html

digger any decent 250sx settings for the Keihin?
2021 sea level...I hear the NECJ but always interested in opinions
thx!
Bart149
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Bart149 8/4/2022 5:00am
8/4/2022 5:00am
I could not find anything from Dynodan. How do I know if it is detonating.
digger
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digger 8/4/2022 5:03am
8/4/2022 5:03am
Bruce372 wrote:
I've used keihin carbs on multiple 125s and 150s, I would stay away from the straight taper keihin needles, I always had detonation issues. The KTM...
I've used keihin carbs on multiple 125s and 150s, I would stay away from the straight taper keihin needles, I always had detonation issues.

The KTM Oem needles will work, NOZI or NIEF etc. The only issue is getting the needle diameter matched up perfectly with the pilot and slide.

Search dynodan on here, he posted the settings.

I have the Sam's carb on ktm 125 and 150 right now we are running the stic insert though.
I haven't noticed any more detonation issues using the single taper CCx needles in the Keihin, than I did using the Mikuni. These engines are right on the edge of detonation from the factory, and just a little bit of bad gas will push them into it. I've only seen 1 piston, out of a 21' 125, that had to be replaced due to detonation. He now mixes 1.5 gal of C12 to 3.5 gals of 93. I have a STIC setup for him after he locks up his GNCC class championship. The detonation was with the Mikuni on the bike.

I really don't like that NOZx and it's 1/2 clip position brother N1Ex triple taper series. That's quite the span that you have listed, I (W)--F starting diameters. I get what they are trying to do with the short straight section, on the small bore bikes, which can be made to work, but I really don't like it on the bigger bikes. I just think it's easier, and more consistent to get the straight taper needles to work in the small bore bikes.

Honda made a triple taper needle that worked really well in the small bore bikes, but it's no longer available. I've tried using the duel taper Yamaha N3xx series needles in the small bore KTM's, but I couldn't get them to work with a 6.5/7.0 slide. I suspect they need a 6.0 slide to make them work correctly. I have used 6.0 slide in a 21' Sherco 125 along with the Duel taper N3Cx needle, and that bike runs really well.

digger
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digger 8/4/2022 5:05am
8/4/2022 5:05am
Bart149 wrote:
I could not find anything from Dynodan. How do I know if it is detonating.
The engine will rattle. It will almost sound like a spray paint can noise.
digger
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digger 8/4/2022 5:14am
8/4/2022 5:14am
opyguy wrote:
digger any decent 250sx settings for the Keihin?
2021 sea level...I hear the NECJ but always interested in opinions
thx!
That NExx needle is a great series needle for that bike, because it helps smooth out the transition from low to mid. That engines handle the J diameter pretty well, where as some of the other MX 250's don't really. So long as you are using a 6.5 or 7.0 slide, I would start off with the NECJ in #3 clip, 40 pilot, and 172 main. A/S at 1.5. This will get you pretty close.
Bruce372
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Bruce372 8/4/2022 6:50am
8/4/2022 6:50am
Bruce372 wrote:
I've used keihin carbs on multiple 125s and 150s, I would stay away from the straight taper keihin needles, I always had detonation issues. The KTM...
I've used keihin carbs on multiple 125s and 150s, I would stay away from the straight taper keihin needles, I always had detonation issues.

The KTM Oem needles will work, NOZI or NIEF etc. The only issue is getting the needle diameter matched up perfectly with the pilot and slide.

Search dynodan on here, he posted the settings.

I have the Sam's carb on ktm 125 and 150 right now we are running the stic insert though.
digger wrote:
I haven't noticed any more detonation issues using the single taper CCx needles in the Keihin, than I did using the Mikuni. These engines are right...
I haven't noticed any more detonation issues using the single taper CCx needles in the Keihin, than I did using the Mikuni. These engines are right on the edge of detonation from the factory, and just a little bit of bad gas will push them into it. I've only seen 1 piston, out of a 21' 125, that had to be replaced due to detonation. He now mixes 1.5 gal of C12 to 3.5 gals of 93. I have a STIC setup for him after he locks up his GNCC class championship. The detonation was with the Mikuni on the bike.

I really don't like that NOZx and it's 1/2 clip position brother N1Ex triple taper series. That's quite the span that you have listed, I (W)--F starting diameters. I get what they are trying to do with the short straight section, on the small bore bikes, which can be made to work, but I really don't like it on the bigger bikes. I just think it's easier, and more consistent to get the straight taper needles to work in the small bore bikes.

Honda made a triple taper needle that worked really well in the small bore bikes, but it's no longer available. I've tried using the duel taper Yamaha N3xx series needles in the small bore KTM's, but I couldn't get them to work with a 6.5/7.0 slide. I suspect they need a 6.0 slide to make them work correctly. I have used 6.0 slide in a 21' Sherco 125 along with the Duel taper N3Cx needle, and that bike runs really well.

Did anyone complain about ktm125 jetting for the 20 years before they swapped to mikuni? I can't remember, lol.

But Nozi and NIEF have come as oem needles for the ktm125 for a very long time so thats why I am suggesting it as a starting point. If you have a better setting then cool.
digger
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digger 8/4/2022 8:45am
8/4/2022 8:45am
Bruce372 wrote:
Did anyone complain about ktm125 jetting for the 20 years before they swapped to mikuni? I can't remember, lol. But Nozi and NIEF have come as...
Did anyone complain about ktm125 jetting for the 20 years before they swapped to mikuni? I can't remember, lol.

But Nozi and NIEF have come as oem needles for the ktm125 for a very long time so thats why I am suggesting it as a starting point. If you have a better setting then cool.
I imagine that most people with those bikes were using them for MX, and they work fine, once off the first taper. I just don't like how they work at 1/4 throttle and under. They(tuners) are trying to compensate for that super rich/short 1st taper by using , what I consider a lean starting diameters, W/K, for a small bore bike. I'm trying to make the bike work from 0 to 100% . I'm thinking of the guys that are using the bikes for GNCC/HS as well as MX.

If I was going to try a triple taper needle that I thought would work, the way I want it to, I would try a Kawasaki/Suzuki N3y/wG needle.
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jcp411 8/7/2022 5:25pm
8/7/2022 5:25pm Edited Date/Time 8/7/2022 5:50pm
Bart149 wrote:
I'm not sure what the needles are it's just a kit that says 125/150cc that comes with the carb. There setting seam a little on the...
I'm not sure what the needles are it's just a kit that says 125/150cc that comes with the carb. There setting seam a little on the rich side. Since I am going for max horsepower I think I will try the CCL and CCM needles. Thank You for your help.
I’m using the same jetting that digger gave you and it works very good. Just make sure you set the float level to 8mm. I fought jetting for awhile till i figured out the float level was set to high.
Zeb Steele
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Zeb Steele 4/13/2023 1:30pm
4/13/2023 1:30pm

Have a question used the jetting recommendations from above 

Elevation 5500'

temp 30-70 degrees

Main Jett 175

Pilot 50 

Needle CCL 4th clip down 

Float height 8mm

1mm of squish 

Fuel run 91 with 112 Sunoco 1 gallon to 4.  

Also run U4.4 at races and Jett accordingly to elevation and fuel 

Have a stutter about 3/8 to 1/2 throttle in every gear when you hold it steady.  It powers through it no problem. Bike is crisp other than that.  Have messed around with pilot from 42-50, needle from CCL-CCM  The current setup seems about the best.  

Pit Row

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digger
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digger 4/13/2023 7:37pm
4/13/2023 7:37pm
Zeb Steele wrote:
Have a question used the jetting recommendations from above  Elevation 5500' temp 30-70 degrees Main Jett 175 Pilot 50  Needle CCL 4th clip down  Float height...

Have a question used the jetting recommendations from above 

Elevation 5500'

temp 30-70 degrees

Main Jett 175

Pilot 50 

Needle CCL 4th clip down 

Float height 8mm

1mm of squish 

Fuel run 91 with 112 Sunoco 1 gallon to 4.  

Also run U4.4 at races and Jett accordingly to elevation and fuel 

Have a stutter about 3/8 to 1/2 throttle in every gear when you hold it steady.  It powers through it no problem. Bike is crisp other than that.  Have messed around with pilot from 42-50, needle from CCL-CCM  The current setup seems about the best.  

Which # slide-are you using ?

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Zeb Steele 4/13/2023 9:00pm
4/13/2023 9:00pm

It’s a 6.5 slide 

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Zeb Steele 4/18/2023 9:31am
4/18/2023 9:31am

Same jetting tried CCL Needle 5th clip down mid range studded almost not there.  

Tried CCM needle 2nd clip up, terrible studder at around 1/4 to 3/8 throttle.  

My question is will a 6.0 slide help?  

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FGR01 4/18/2023 10:37am
4/18/2023 10:37am
Zeb Steele wrote:
Same jetting tried CCL Needle 5th clip down mid range studded almost not there.   Tried CCM needle 2nd clip up, terrible studder at around 1/4...

Same jetting tried CCL Needle 5th clip down mid range studded almost not there.  

Tried CCM needle 2nd clip up, terrible studder at around 1/4 to 3/8 throttle.  

My question is will a 6.0 slide help?  

What exact bike are we talking about here?

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Zeb Steele 4/18/2023 12:10pm
4/18/2023 12:10pm

FGR01

We are talking about 2022 Husky 125 with Keihn 38mm carb, two post above is the jetting specs

 

Bart149
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Bart149 4/18/2023 12:20pm
4/18/2023 12:20pm

FYI. I jetted mine per the manual on a 2016 KTM125 with a Keihn and it runs great.

Bart149
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Bart149 4/18/2023 12:30pm
4/18/2023 12:30pm

2023-04-18 14h26 05.png?VersionId=7bB2ZD.OYE.x

 2023-04-18 14h26 30.png?VersionId=gfgDopUpBR

 

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Zeb Steele 4/18/2023 12:35pm
4/18/2023 12:35pm

Thanks I will try a N1EG Needle 

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FGR01 4/18/2023 12:51pm
4/18/2023 12:51pm
Zeb Steele wrote:

FGR01

We are talking about 2022 Husky 125 with Keihn 38mm carb, two post above is the jetting specs

 

So, there is the "mystery prob" with the 2022+ bikes.  For some reason, some of them just don't seem to jet the same as the 2016-2021 bikes.    In this thread, I made a post about a 2023 GG-MC125 I recently jetted.   The takeaway is that I ended up much leaner on the needle than would be expected.  Also, I am in AZ at probably similar elevation and conditions to you.  Some info for you to consider.

https://www.vitalmx.com/forums/Tech-Help-Race-Shop,42/KTM-HUS-125-150-2…

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Zeb Steele 4/18/2023 1:11pm
4/18/2023 1:11pm

FGR01 

Thanks I will try a N3CK Needle as well 

digger
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digger 4/18/2023 1:29pm
4/18/2023 1:29pm
Zeb Steele wrote:
Same jetting tried CCL Needle 5th clip down mid range studded almost not there.   Tried CCM needle 2nd clip up, terrible studder at around 1/4...

Same jetting tried CCL Needle 5th clip down mid range studded almost not there.  

Tried CCM needle 2nd clip up, terrible studder at around 1/4 to 3/8 throttle.  

My question is will a 6.0 slide help?  

You're going in 2 different directions there. The CCL needle has a richer starting diameter than the CCM, so CCL in clip position #5 is much ,much richer than CCM in #2. That N3CK needle is quite a bit leaner than either of the CC L or M needles.  I use a #7 slide with the CCx needles in the KTM based 125/150's. 

I wish I could give you better/ more definitive info to help, but something change on the 22+ KTM small bores, and I'm not really sure what. They simply do not jet consistently. 

The new 125 Yamaha's, with the Keihin and #7 slide, like to use a DCL or DCM needle, which has a richer taper than the CCx needles.

 

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FGR01 4/18/2023 1:50pm
4/18/2023 1:50pm
Zeb Steele wrote:

FGR01 

Thanks I will try a N3CK Needle as well 

Pay attention to what Digger has said - N3CK is a very lean needle.  Notice I am on a 188 main.  That's 5 sizes bigger than your 175.    Don't drop the N3CK in with a 175 main.

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