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

AJ565
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AJ565 8/25/2021 10:45am
8/25/2021 10:45am
swatdoc wrote:
AJ / Digger: Just to clarify - the 150 specs on the first page - for the pilot jet - is that with NO notch filed...
AJ / Digger:

Just to clarify - the 150 specs on the first page - for the pilot jet - is that with NO notch filed on the front of the #5 slide??

I have filed the front notch to Digger's specs - so if the page one specs are for NO notch, then the pilot jet baseline should therefore be 30 WITH the notch??

I've seen AJ mention a few times running a 500 main jet in the 150 - would you say try that first as the baseline?

How would all the settings differ for hot temps - it's running 90-100 in SoCal all this week.

Just got my cylinder and head back from Lynks so I'm gonna do the carb mods finally

Thanks
No notch should be the 32.5. The notch makes the pilot jet circuit more efficient so you’d need the bigger jet without the notch. Personally I’ve had good luck with the 500 main in the bikes. You may need to drop it down or even go bigger. These are just a solid starting point in the right direction compared to the terrible stock settings.
1
Pymmer637 8/25/2021 2:08pm
8/25/2021 2:08pm
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a 0-2000ft DA area. Would you recommend anything different than what’s added in at the beginning of the thread and edited in late 2020?
opyguy
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opyguy 8/25/2021 4:08pm
8/25/2021 4:08pm Edited Date/Time 8/25/2021 4:10pm
Pymmer637 wrote:
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a...
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a 0-2000ft DA area. Would you recommend anything different than what’s added in at the beginning of the thread and edited in late 2020?
Hey for what it’s worth I had a 17 and used AJ specs and it was awesome… However I have a 21 now with stock jetting, I haven’t touched it and it has run phenomenal.
If you get a chance try to stock jetting first and then post if you decide to change ....I’m curious how it runs with his specs as well
Pymmer637 8/25/2021 6:19pm
8/25/2021 6:19pm
Pymmer637 wrote:
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a...
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a 0-2000ft DA area. Would you recommend anything different than what’s added in at the beginning of the thread and edited in late 2020?
opyguy wrote:
Hey for what it’s worth I had a 17 and used AJ specs and it was awesome… However I have a 21 now with stock jetting...
Hey for what it’s worth I had a 17 and used AJ specs and it was awesome… However I have a 21 now with stock jetting, I haven’t touched it and it has run phenomenal.
If you get a chance try to stock jetting first and then post if you decide to change ....I’m curious how it runs with his specs as well
I’ve already got 11 hours on it. It runs a little rich and feels sluggish in the corners

The Shop

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swatdoc
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swatdoc 8/25/2021 6:36pm
8/25/2021 6:36pm
Thanks AJ - I'll start with the 30 PJ since I have the notch, and go with the 500 MJ for the initial setting.
AJ565
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AJ565 8/25/2021 6:43pm
8/25/2021 6:43pm
Pymmer637 wrote:
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a...
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a 0-2000ft DA area. Would you recommend anything different than what’s added in at the beginning of the thread and edited in late 2020?
The last new bike I messed with was a ‘21 and it perfected the 5.75 slide and 500 main that I have on the first page. It didn’t like it too much with oxygenated race fuel. I haven’t been able to test anymore with it tho. So the settings are a good start, but you might have to fine tune.
Pymmer637 8/25/2021 7:01pm
8/25/2021 7:01pm
Pymmer637 wrote:
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a...
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a 0-2000ft DA area. Would you recommend anything different than what’s added in at the beginning of the thread and edited in late 2020?
AJ565 wrote:
The last new bike I messed with was a ‘21 and it perfected the 5.75 slide and 500 main that I have on the first page...
The last new bike I messed with was a ‘21 and it perfected the 5.75 slide and 500 main that I have on the first page. It didn’t like it too much with oxygenated race fuel. I haven’t been able to test anymore with it tho. So the settings are a good start, but you might have to fine tune.
I take it this is with stock internals and no mods? Thanks for reply!
AJ565
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AJ565 8/25/2021 9:51pm
8/25/2021 9:51pm
Pymmer637 wrote:
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a...
Hey AJ, I just picked up a 2022 250 sx, I got a fmf factory fatty and 2.1 shorty silencer for it. I live in a 0-2000ft DA area. Would you recommend anything different than what’s added in at the beginning of the thread and edited in late 2020?
AJ565 wrote:
The last new bike I messed with was a ‘21 and it perfected the 5.75 slide and 500 main that I have on the first page...
The last new bike I messed with was a ‘21 and it perfected the 5.75 slide and 500 main that I have on the first page. It didn’t like it too much with oxygenated race fuel. I haven’t been able to test anymore with it tho. So the settings are a good start, but you might have to fine tune.
Pymmer637 wrote:
I take it this is with stock internals and no mods? Thanks for reply!
Correct.
yota
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yota 8/28/2021 11:21am
8/28/2021 11:21am
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to loosening the carb clamps and pulling the carb back towards the airbox to remove but this airbox boot does not seem to flex at all. did not want to force it.
AJ565
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AJ565 8/28/2021 11:26am
8/28/2021 11:26am
yota wrote:
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to...
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to loosening the carb clamps and pulling the carb back towards the airbox to remove but this airbox boot does not seem to flex at all. did not want to force it.
Yes. However you can do all the work needed just turning the carb sideways.
yota
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yota 8/28/2021 12:15pm
8/28/2021 12:15pm
yota wrote:
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to...
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to loosening the carb clamps and pulling the carb back towards the airbox to remove but this airbox boot does not seem to flex at all. did not want to force it.
AJ565 wrote:
Yes. However you can do all the work needed just turning the carb sideways.
thanks a lot AJ.
oldslownewb
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oldslownewb 8/28/2021 2:16pm
8/28/2021 2:16pm
Recently having a hard time starting from cold. 32.5 490 5.5 50:1. Changing plugs doesn’t do anything. Only thing that kind of works is choke on about 5-6 real slow pushes with hand on kick starter then normal kick and it sometime it starts. Sometimes seems to flood then shut off gas lean it over kick it gas on then try repeating hand kick procedure? Its somewhat random what works, never almost starts, it’s nothing or fires instantly. Runs great after it starts, only 17 hours on 22 tc250, have had carb apart and cleaned a couple times still the same cold start issue. Any help appreciated my first two stroke.
AJ565
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AJ565 8/28/2021 2:58pm
8/28/2021 2:58pm
oldslownewb wrote:
Recently having a hard time starting from cold. 32.5 490 5.5 50:1. Changing plugs doesn’t do anything. Only thing that kind of works is choke on...
Recently having a hard time starting from cold. 32.5 490 5.5 50:1. Changing plugs doesn’t do anything. Only thing that kind of works is choke on about 5-6 real slow pushes with hand on kick starter then normal kick and it sometime it starts. Sometimes seems to flood then shut off gas lean it over kick it gas on then try repeating hand kick procedure? Its somewhat random what works, never almost starts, it’s nothing or fires instantly. Runs great after it starts, only 17 hours on 22 tc250, have had carb apart and cleaned a couple times still the same cold start issue. Any help appreciated my first two stroke.
Did you check the float height?
oldslownewb
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oldslownewb 8/28/2021 3:38pm
8/28/2021 3:38pm
Yes float set to 8mm
Jon Bingham
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Jon Bingham 8/28/2021 6:23pm
8/28/2021 6:23pm
yota wrote:
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to...
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to loosening the carb clamps and pulling the carb back towards the airbox to remove but this airbox boot does not seem to flex at all. did not want to force it.
You're probably gonna want to change the jet block gasket too..... get the one from JD jetting. The stock gasket is junk and even at 10.5hrs. it is probably already deformed.
AJ565
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AJ565 8/29/2021 6:35am
8/29/2021 6:35am
oldslownewb wrote:
Yes float set to 8mm
I’m not sure what 8mm looks like on that carb. I’ve always set it so the float is perpendicular to the bottom of the carb when the plunger just starts to touch.
yota
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yota 8/29/2021 2:02pm
8/29/2021 2:02pm
first ride today on 2021 TC125 with 10.4 hours. had to try the stock jetting it came with and confirms everything you guys have come up with. bike will rev pretty cleanly once the crankcase clears out but if you stop revving it loads up again pretty fast. blubbery and maybe a touch lean at the very top if you hold it there. will be ordering stuff tonight.
yota
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yota 8/29/2021 2:37pm
8/29/2021 2:37pm Edited Date/Time 8/29/2021 2:51pm
neva mind. (:

Pit Row

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fredmotokx 8/29/2021 2:40pm
8/29/2021 2:40pm
yota wrote:
neva mind. (:
KTM or Yamaha part numbers have pretty much all the option jet. For the slide, you can buy one from JDjetting or cut it yourself.
yota
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yota 8/29/2021 2:50pm
8/29/2021 2:50pm
yota wrote:
neva mind. (:
fredmotokx wrote:
KTM or Yamaha part numbers have pretty much all the option jet. For the slide, you can buy one from JDjetting or cut it yourself.
found the stuff at Motosport right after I posted this. thanks.
AJ565
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AJ565 8/29/2021 5:08pm
8/29/2021 5:08pm
yota wrote:
neva mind. (:
fredmotokx wrote:
KTM or Yamaha part numbers have pretty much all the option jet. For the slide, you can buy one from JDjetting or cut it yourself.
The Yamaha parts are a little cheaper for the same part which is why those are listed.
yota
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yota 8/30/2021 4:48am
8/30/2021 4:48am
yota wrote:
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to...
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to loosening the carb clamps and pulling the carb back towards the airbox to remove but this airbox boot does not seem to flex at all. did not want to force it.
Jon Bingham wrote:
You're probably gonna want to change the jet block gasket too..... get the one from JD jetting. The stock gasket is junk and even at 10.5hrs...
You're probably gonna want to change the jet block gasket too..... get the one from JD jetting. The stock gasket is junk and even at 10.5hrs. it is probably already deformed.
I did order that. thanks.
digger
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digger 8/30/2021 6:09am
8/30/2021 6:09am
yota wrote:
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to...
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to loosening the carb clamps and pulling the carb back towards the airbox to remove but this airbox boot does not seem to flex at all. did not want to force it.
I just worked on one of these bikes, TC 125, 2 weeks ago. It wound up very close to the specs that have been listed here many times.

New jet block gasket.
42-74---in clip #2
5.0 slide. I modified the oem #4 into a #5. I notched front side with a 5/32 or 4mm file. I do recommend that you do it, but it isn't totally necessary.
30--pilot jet---use this as the starting point, with the air screw @ 2 turns out.
The bike is being used for off road/ GNCC racing, so we used a 490 main, which i feel is large enough for that type of racing/riding at this time of year.
Him and his father were very happy with the final settings.
yota
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yota 8/30/2021 8:00am
8/30/2021 8:00am
yota wrote:
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to...
just got a 21 TC125, completely stock with 10.4 hours on it. does the subframe need to come off to remove the carb? I'm used to loosening the carb clamps and pulling the carb back towards the airbox to remove but this airbox boot does not seem to flex at all. did not want to force it.
digger wrote:
I just worked on one of these bikes, TC 125, 2 weeks ago. It wound up very close to the specs that have been listed here...
I just worked on one of these bikes, TC 125, 2 weeks ago. It wound up very close to the specs that have been listed here many times.

New jet block gasket.
42-74---in clip #2
5.0 slide. I modified the oem #4 into a #5. I notched front side with a 5/32 or 4mm file. I do recommend that you do it, but it isn't totally necessary.
30--pilot jet---use this as the starting point, with the air screw @ 2 turns out.
The bike is being used for off road/ GNCC racing, so we used a 490 main, which i feel is large enough for that type of racing/riding at this time of year.
Him and his father were very happy with the final settings.
thanks digger. your help and AJ's has been great for everyone. yesterdays ride was 94F and humidity almost 90%. elevation is 50 to 100 ft above sea level.
3
Pymmer637 8/30/2021 12:47pm
8/30/2021 12:47pm
AJ I see you live in New York. I live in Ontario and weather is quite similar. When it’s gets colder out starting middle of September-ish what have you changed that’s worked the best for you compared to the 500 main and all that stuff?
AJ565
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AJ565 8/30/2021 3:01pm
8/30/2021 3:01pm
Pymmer637 wrote:
AJ I see you live in New York. I live in Ontario and weather is quite similar. When it’s gets colder out starting middle of September-ish...
AJ I see you live in New York. I live in Ontario and weather is quite similar. When it’s gets colder out starting middle of September-ish what have you changed that’s worked the best for you compared to the 500 main and all that stuff?
I’m not sure why it says that, but I live in Texas. As far as colder temps when it gets in the 30-40’s here I have to bump up the pilot and move the clip down one.
Pymmer637 8/30/2021 4:17pm
8/30/2021 4:17pm
Pymmer637 wrote:
AJ I see you live in New York. I live in Ontario and weather is quite similar. When it’s gets colder out starting middle of September-ish...
AJ I see you live in New York. I live in Ontario and weather is quite similar. When it’s gets colder out starting middle of September-ish what have you changed that’s worked the best for you compared to the 500 main and all that stuff?
AJ565 wrote:
I’m not sure why it says that, but I live in Texas. As far as colder temps when it gets in the 30-40’s here I have...
I’m not sure why it says that, but I live in Texas. As far as colder temps when it gets in the 30-40’s here I have to bump up the pilot and move the clip down one.
Okay thanks, I’ll have have to fuck around with it once it starts to cool off here, probably around low 60s here soon
AJ565
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AJ565 8/30/2021 5:45pm
8/30/2021 5:45pm
Pymmer637 wrote:
AJ I see you live in New York. I live in Ontario and weather is quite similar. When it’s gets colder out starting middle of September-ish...
AJ I see you live in New York. I live in Ontario and weather is quite similar. When it’s gets colder out starting middle of September-ish what have you changed that’s worked the best for you compared to the 500 main and all that stuff?
AJ565 wrote:
I’m not sure why it says that, but I live in Texas. As far as colder temps when it gets in the 30-40’s here I have...
I’m not sure why it says that, but I live in Texas. As far as colder temps when it gets in the 30-40’s here I have to bump up the pilot and move the clip down one.
Pymmer637 wrote:
Okay thanks, I’ll have have to fuck around with it once it starts to cool off here, probably around low 60s here soon
I normally don’t need to change anything until the 40’s.
1
huckster mcplush 9/1/2021 11:28am
9/1/2021 11:28am Edited Date/Time 9/2/2021 11:32am
huckster mcplush wrote:
Ok, heading out riding tomorrow with another fuel/oil test on my 2017 ktm 150xcw (TMX 38)... As suggested by many on vital, I am trying out...
Ok, heading out riding tomorrow with another fuel/oil test on my 2017 ktm 150xcw (TMX 38)... As suggested by many on vital, I am trying out a new premix oil with a lower flash point to hopefully better suit my riding style. I am going to try Amsoil Interceptor mixed at 50:1 (as per the recommendation on the bottle, thoughts?) My jetting is the same as the 150 specs listed on the 1st page. I did try in a separate test, going back to the stock silencer from the fmf turbinecore 2.1 spark arrestor (both paired with a fmf fatty pipe)... Seems to rev quicker and have better bottom end. I don't get the chance to ride often, so I should have done a back to back test in the same session, but I was pressed for time Sad With that silencer, having it want to rev quicker makes me want to try the green PV spring with it, as I don't spend a lot of time in the upper rpms...Hoping it will give me more gear to play with before I puss out and short shift the thing Tongue My test setup for tomorrow will be as follows:

PJ - 32.5
MJ - 490
Needle Jet - S4
Needle - 42-74
clip pos 2
AS 1.5t out
slide 5.0 *no notch on front
PV 3 turns in from fully CCW (to delay hit/lengthen gears)
Yellow PV spring
RKtek insert milled for 88oct
Marathon "recreation fuel (non ethanol 90)"
Amsoil Interceptor @50:1

Will write back post-test... Hoping that someone else who rides like I do can either help or be helped by my tinkering Smile Thanks.

Okay finally got to test this setup out. I also fitted the Green spring at 3.5 turns in paired with the stock silencer. As before the stock silencer does seem to let the bike Rev quicker and freer then with the spark arrestor. I found myself being in a gear lower up technical hill climbs with that setup which makes me feel something that I changed took away some low end grunt. Going to try going back to the yellow spring with the turbine core. From a spooge standpoint with the interceptor oil, I rode for about 3 hours with speeds from trials crawling lug fest to moderately ringing it out on the track. Seemed to smoke much less and there wasn't any drool coming out the silencer at the end of the day. I still feel that I am a bit rich on the pilot though. I did a little experiment with the air screw yesterday and aside from turning it all the way in which of course made it die, no matter how far I turned it out, it did not cause a change in the idle speed. So just to test further I kept unscrewing till I got the needle completely out, then the idle went up so I'm thinking about going down to a 30 pilot from a 32.5 to see if I get a response from the air screw. Looking at the spark plug tells me I am rich somewhere, guessing it is the pilot since that's where I spend most of my time. Mid-range seems fine and it doesn't seem to load up or gurgle at any point once it's fully warmed up. I also want to eliminate any possibility of jet and confusion by doing a leak down test. If anything it could be a clutch side crank seal. I would think my spark plug would tell me otherwise if I had an air leak. Maybe I'm just being too picky and expecting it to run super clean like a 4-stroke haha. Sorry I said the f word :-) anyway I've rambled long enough.

Any thoughts Digger or AJ? Thanks guys.



swatdoc
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swatdoc 9/1/2021 5:18pm
9/1/2021 5:18pm Edited Date/Time 9/1/2021 7:29pm
oldslownewb wrote:
Yes float set to 8mm
AJ565 wrote:
I’m not sure what 8mm looks like on that carb. I’ve always set it so the float is perpendicular to the bottom of the carb when...
I’m not sure what 8mm looks like on that carb. I’ve always set it so the float is perpendicular to the bottom of the carb when the plunger just starts to touch.
Just checked my float height while re-jetting my carb. Stock was way off: 4mm.

Reset mine to 7mm, which is right at the point where the floats are parallel to the bottom edge of the carb (like AJ describes). Had to tweak that arm that holds the needle valve quite a bit.

Replaced the jet block gasket too - what a PITA - ended up using a tiny bit of grease to hold it in place while finagling it back into place. The gasket looked fine, although I only have 4 hrs on my bike - but might as well do it now when I have the carb off. Would have had to do it sooner or later anyway.

Post a reply to: 125/150/250/300 KTM/HUS/GG jetting thread