KTM 250 SX 2018

mx4all
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mx4all
Edited Date/Time 5/27/2020 5:03am


Bought a new bike recently so I figured I would do a thread in here to get some info on how to set it up.
Haven't ridden 2 strokes in 15 years.

Bought it with 20 hours on it. The previous owner put on a HGS exhaust and let a shop tune it and benched it.





I have done two practices on the bike and she hits like a mother f***er and screams like a bit*h.
I have never got this tired trying hold on to any previous bike. Got to put on a seat with better grip I guess.

I saw on the bench papers that I got the red spring in it so I will try the yellow and the green next time and see how it feels.
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opyguy
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opyguy 6/12/2019 7:54am
6/12/2019 7:54am
very interesting dyno's.
What does the term "varv" mean?
2varv, rod-4.5varv in?
r18b
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r18b 6/12/2019 9:16am
6/12/2019 9:16am
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1?

Or do i see it wrong?

If i remember right some one here was saying his 250sx was pulling 51hp with a pc pipe and some vp fuel. Now i see this i wonder how much difference there is in a dyno or that he was sucking his big thump to get those nummers.
mx4all
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mx4all 6/12/2019 9:28am
6/12/2019 9:28am
opyguy wrote:
very interesting dyno's.
What does the term "varv" mean?
2varv, rod-4.5varv in?
It means turns.
450, 42.5, 43-73/2, 2 turns, red spring, 2.25 turns in.
I guess it means
Main jet 450
Pilot 42,5
Needle 43-73, second position?
2 turns air screw ?
Red spring
2.25 turns in on powervalve?

I am not sure maybe someone with more experience of two strokes can tell us.

mx4all
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mx4all 6/12/2019 9:41am
6/12/2019 9:41am
r18b wrote:
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1? Or do i see it wrong? If i remember right some one here...
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1?

Or do i see it wrong?

If i remember right some one here was saying his 250sx was pulling 51hp with a pc pipe and some vp fuel. Now i see this i wonder how much difference there is in a dyno or that he was sucking his big thump to get those nummers.
44.4hp and 41m.N with the HGS exhaust and pump fuel yes.
40.4hp and 38.9mN stocker.
These figures are on the back wheel, his numbers maybe were on the engine?
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r18b
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r18b 6/12/2019 10:03am
6/12/2019 10:03am
Thanks.. but don't know he was just saying it not showing a dyno result like this. So in that way i take it always with some salt. Think he will read this lol

That are some nice nummers for a just a different pipe. HGS is always a good pipe. Enjoy the ride!
EnvyMedia 6/12/2019 11:57pm
6/12/2019 11:57pm Edited Date/Time 6/13/2019 12:00am
r18b wrote:
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1? Or do i see it wrong? If i remember right some one here...
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1?

Or do i see it wrong?

If i remember right some one here was saying his 250sx was pulling 51hp with a pc pipe and some vp fuel. Now i see this i wonder how much difference there is in a dyno or that he was sucking his big thump to get those nummers.
Seems pretty low. The owner of GL12 racing claimed their 250’s made 59hp. I thought stock was 48 or 49?
mx4all
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mx4all 6/13/2019 12:33am
6/13/2019 12:33am
r18b wrote:
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1? Or do i see it wrong? If i remember right some one here...
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1?

Or do i see it wrong?

If i remember right some one here was saying his 250sx was pulling 51hp with a pc pipe and some vp fuel. Now i see this i wonder how much difference there is in a dyno or that he was sucking his big thump to get those nummers.
EnvyMedia wrote:
Seems pretty low. The owner of GL12 racing claimed their 250’s made 59hp. I thought stock was 48 or 49?
If I find my gopro I can do a video of me riding it so you can hear her scream =)
sandman768
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sandman768 6/13/2019 4:13am
6/13/2019 4:13am
Lots of good info on here, as for the “hit” is the gearing stock? If so, try dropping 1 tooth on rear sprocket, it helps tame the hit in second gear and spreads out the shift points...at first I was not sure about the gearing change, give it some time, it will result in better lap times & less fatigue....nice bike...
EnvyMedia 6/13/2019 6:28am
6/13/2019 6:28am
r18b wrote:
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1? Or do i see it wrong? If i remember right some one here...
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1?

Or do i see it wrong?

If i remember right some one here was saying his 250sx was pulling 51hp with a pc pipe and some vp fuel. Now i see this i wonder how much difference there is in a dyno or that he was sucking his big thump to get those nummers.
EnvyMedia wrote:
Seems pretty low. The owner of GL12 racing claimed their 250’s made 59hp. I thought stock was 48 or 49?
mx4all wrote:
If I find my gopro I can do a video of me riding it so you can hear her scream =)
If I find my gopro I can do a video of me riding it so you can hear her scream =)
I bet she screams! Congrats on your nice ride.
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r18b 6/13/2019 12:40pm
6/13/2019 12:40pm
Dyno with a jvs pipe on a 2019-2020.

1
mx4all
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mx4all 6/14/2019 8:07am
6/14/2019 8:07am
What's up guys.

I will try some suspension tomorrow. Two different links and two shocks.
What sag numbers are you guys with the same bike running?
The owners manual says 35mm and 105mm I think but someone maybe done some testing already?
Have put on my conevalve fork too.


mx4all
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mx4all 6/14/2019 8:08am
6/14/2019 8:08am
EnvyMedia wrote:
Seems pretty low. The owner of GL12 racing claimed their 250’s made 59hp. I thought stock was 48 or 49?
mx4all wrote:
If I find my gopro I can do a video of me riding it so you can hear her scream =)
If I find my gopro I can do a video of me riding it so you can hear her scream =)
EnvyMedia wrote:
I bet she screams! Congrats on your nice ride.
Thank you Smile
mx4all
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mx4all 6/14/2019 8:10am
6/14/2019 8:10am
sandman768 wrote:
Lots of good info on here, as for the “hit” is the gearing stock? If so, try dropping 1 tooth on rear sprocket, it helps tame...
Lots of good info on here, as for the “hit” is the gearing stock? If so, try dropping 1 tooth on rear sprocket, it helps tame the hit in second gear and spreads out the shift points...at first I was not sure about the gearing change, give it some time, it will result in better lap times & less fatigue....nice bike...
I put 13x48 on so I use 3 gear in most corners, never have to use second. Third is taller and pulls pretty far out of the corners
kdubsteezey
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kdubsteezey 6/14/2019 9:00am
6/14/2019 9:00am
My 17 was a fire breather too.... I ran the stock PV spring (yellow?) 1 turn counter clockwise from stock setting (drawing a blank on what that was...) PC works pipe and really liked the stock silencer actually over the PC shorty. It made good torque, smoothed out the hit a little bit and made the power carry longer. The hit was fun but I realized unless your planning to go drag race quads at the dunes 🙄 The smoother longer power equaled faster lap times and charging harder late in Motos. Still the thing was wicked fast haha. I ran stock 49t sprocket and used the clutch and carried 3rd through most corners. kinda wished I tried a 48 though... just my 2 cents.
mx4all
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mx4all 6/14/2019 10:42am
6/14/2019 10:42am
Threw the yellow spring in the powervalve and put a different clamp on with phds bar mounts, takes away some harshness Smile



Also threw on a different shock and linkage. Set it up with 38 and 108mm sag. Had 35 and 105 with the other shock and felt like I got a lot of wheelspin and no traction so I hope this will work better.
mx4all
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mx4all 6/14/2019 10:50am
6/14/2019 10:50am
kdubsteezey wrote:
My 17 was a fire breather too.... I ran the stock PV spring (yellow?) 1 turn counter clockwise from stock setting (drawing a blank on what...
My 17 was a fire breather too.... I ran the stock PV spring (yellow?) 1 turn counter clockwise from stock setting (drawing a blank on what that was...) PC works pipe and really liked the stock silencer actually over the PC shorty. It made good torque, smoothed out the hit a little bit and made the power carry longer. The hit was fun but I realized unless your planning to go drag race quads at the dunes 🙄 The smoother longer power equaled faster lap times and charging harder late in Motos. Still the thing was wicked fast haha. I ran stock 49t sprocket and used the clutch and carried 3rd through most corners. kinda wished I tried a 48 though... just my 2 cents.
Nice! Thanks for sharing your setup and info.

I have only done 2 rides on it yet and feelt the suspension was harsh, I had no traction and the bike were very aggressive. So I hope changes on it and my testing tomorrow will get me some more confident on the bike and be able to ride it for longer.
I usually can do 30 min motos on a 450 sxf no problem but with this bike I can barely do a few laps in race pace duo to the powercurve and suspension.
opyguy
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opyguy 6/14/2019 11:29am
6/14/2019 11:29am
factory connection had me as low as 110 on rider sag
I'm 6'2" 195 and went up to the 4.5 spring from the 450sxf (stock is 4.2 on the 250sx)
110 worked well on fast tracks and sand tracks, hard pack I turned adjuster in 1 full turn and could feel front end bite better
lukemoto
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lukemoto 6/15/2019 6:29am
6/15/2019 6:29am
kdubsteezey wrote:
My 17 was a fire breather too.... I ran the stock PV spring (yellow?) 1 turn counter clockwise from stock setting (drawing a blank on what...
My 17 was a fire breather too.... I ran the stock PV spring (yellow?) 1 turn counter clockwise from stock setting (drawing a blank on what that was...) PC works pipe and really liked the stock silencer actually over the PC shorty. It made good torque, smoothed out the hit a little bit and made the power carry longer. The hit was fun but I realized unless your planning to go drag race quads at the dunes 🙄 The smoother longer power equaled faster lap times and charging harder late in Motos. Still the thing was wicked fast haha. I ran stock 49t sprocket and used the clutch and carried 3rd through most corners. kinda wished I tried a 48 though... just my 2 cents.
mx4all wrote:
Nice! Thanks for sharing your setup and info. I have only done 2 rides on it yet and feelt the suspension was harsh, I had no...
Nice! Thanks for sharing your setup and info.

I have only done 2 rides on it yet and feelt the suspension was harsh, I had no traction and the bike were very aggressive. So I hope changes on it and my testing tomorrow will get me some more confident on the bike and be able to ride it for longer.
I usually can do 30 min motos on a 450 sxf no problem but with this bike I can barely do a few laps in race pace duo to the powercurve and suspension.
I came off a 450 too and agree with you the 250 takes it out of you quick. One thing that really helped me was cleaning up the bottom end. Once I found the right jetting (needle position helped the most) the powerband comes on so seamlessly now and its much easier for me to stay loose and lay down smooth laps.

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lukemoto 6/15/2019 6:37am
6/15/2019 6:37am
opyguy wrote:
factory connection had me as low as 110 on rider sag I'm 6'2" 195 and went up to the 4.5 spring from the 450sxf (stock is...
factory connection had me as low as 110 on rider sag
I'm 6'2" 195 and went up to the 4.5 spring from the 450sxf (stock is 4.2 on the 250sx)
110 worked well on fast tracks and sand tracks, hard pack I turned adjuster in 1 full turn and could feel front end bite better
I'm the exact same stats as you, I have the front pretty dialed but still need to find a better shock setup. I'm running 105 sag, 15c, 15r, 2.5 high speed. It tracks very well but kicks a lot. I'm really wanting to try the pro circuit or sdi linkage next. Have any of you tried the complete knuckle and arm setup?
mx4all
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mx4all 6/15/2019 8:08am
6/15/2019 8:08am
Any 2 stroke guru that can tell me if my spark plug looks good, too lean or to rich?





mx4all
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mx4all 6/15/2019 1:01pm
6/15/2019 1:01pm
Tried the short linkage and a different shock and the bike works so much better. Also got a conevalve on so it feels pritty good, 100 times better than the air fork and stock setup.

Tried yellow and green spring in the powervalve and liked it much better than the red one. Much easier to ride it now. It was hot today but did a few 20 min motos and it feelt good, much better than my first two practises.
The red spring might be good on deep sand tracks though.

Love how easy the bike is in the air and in the corners! Played a bit in the end and did a few whips.. much fun today!
LaughingLaughing
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lukemoto 6/17/2019 1:04pm
6/17/2019 1:04pm
mx4all wrote:
Tried the short linkage and a different shock and the bike works so much better. Also got a conevalve on so it feels pritty good, 100...
Tried the short linkage and a different shock and the bike works so much better. Also got a conevalve on so it feels pritty good, 100 times better than the air fork and stock setup.

Tried yellow and green spring in the powervalve and liked it much better than the red one. Much easier to ride it now. It was hot today but did a few 20 min motos and it feelt good, much better than my first two practises.
The red spring might be good on deep sand tracks though.

Love how easy the bike is in the air and in the corners! Played a bit in the end and did a few whips.. much fun today!
LaughingLaughing
I love the cone valves easily my favorite upgrade so far. The rk tek head is super nice also!
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AJ565
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AJ565 6/19/2019 11:08am
6/19/2019 11:08am
r18b wrote:
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1? Or do i see it wrong? If i remember right some one here...
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1?

Or do i see it wrong?

If i remember right some one here was saying his 250sx was pulling 51hp with a pc pipe and some vp fuel. Now i see this i wonder how much difference there is in a dyno or that he was sucking his big thump to get those nummers.
Your jetting is to rich causing the low numbers. Stock pipe MXA had 47hp and with a PC pipe and silencer 49hp on a chassis dyno. My bike with a rejet, PC setup, and u4.4 made almost 51hp.
mx4all
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mx4all 6/26/2019 11:21am
6/26/2019 11:21am
What's up everyone

What weight and spring rates do you guys have?
The numbers in the manual is with gear on, right?

I weight 196 and I got a 4.8nm spring and I get 35mm sag and 105mm race sag.

mx4all
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mx4all 6/26/2019 11:25am
6/26/2019 11:25am
r18b wrote:
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1? Or do i see it wrong? If i remember right some one here...
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1?

Or do i see it wrong?

If i remember right some one here was saying his 250sx was pulling 51hp with a pc pipe and some vp fuel. Now i see this i wonder how much difference there is in a dyno or that he was sucking his big thump to get those nummers.
AJ565 wrote:
Your jetting is to rich causing the low numbers. Stock pipe MXA had 47hp and with a PC pipe and silencer 49hp on a chassis dyno...
Your jetting is to rich causing the low numbers. Stock pipe MXA had 47hp and with a PC pipe and silencer 49hp on a chassis dyno. My bike with a rejet, PC setup, and u4.4 made almost 51hp.
U think so? Looking at the sparkplug the bike doesn't seem that overly rich?
opyguy
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opyguy 6/26/2019 11:31am
6/26/2019 11:31am
mx4all wrote:
What's up everyone What weight and spring rates do you guys have? The numbers in the manual is with gear on, right? I weight 196 and...
What's up everyone

What weight and spring rates do you guys have?
The numbers in the manual is with gear on, right?

I weight 196 and I got a 4.8nm spring and I get 35mm sag and 105mm race sag.

195 naked running the 4.5nm from the 450.
35/105 is pretty much perfect, FC recommends running 108/110 for sand/longer tracks
1 turn out and you should be there (108/38)
as long as free sag is between 35-45 after your rider sag you should be good.
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mx4all
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mx4all 6/26/2019 11:35am
6/26/2019 11:35am
r18b wrote:
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1? Or do i see it wrong? If i remember right some one here...
40.4 with the original pipe? 44.4 with a hgs?? Torq 38.1 and 40.1?

Or do i see it wrong?

If i remember right some one here was saying his 250sx was pulling 51hp with a pc pipe and some vp fuel. Now i see this i wonder how much difference there is in a dyno or that he was sucking his big thump to get those nummers.
AJ565 wrote:
Your jetting is to rich causing the low numbers. Stock pipe MXA had 47hp and with a PC pipe and silencer 49hp on a chassis dyno...
Your jetting is to rich causing the low numbers. Stock pipe MXA had 47hp and with a PC pipe and silencer 49hp on a chassis dyno. My bike with a rejet, PC setup, and u4.4 made almost 51hp.
mx4all wrote:
U think so? Looking at the sparkplug the bike doesn't seem that overly rich?
I got Main jet 450
Pilot 42,5
Needle 43-73, second position
2 turns air screw
Green spring
2.25 turns in on powervalve.

I saw pro circuit recommendations was
450, 35 , 3 clip
mx4all
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mx4all 6/27/2019 4:07am
6/27/2019 4:07am
I want to try to get a better pull from the bottom, I got 40 and 37.5 pilot jet so I figured I would try the 37.5 today. The bike wont seaz because of the pilot huh?
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lukemoto 6/27/2019 7:29pm
6/27/2019 7:29pm
Any of you running the trax shock? I finally landed one and I'm itching to get out and dial it in. Its currently set up for a pro rider same weight and bike so I guess I'll just check sag and go from there.
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lukemoto 6/30/2019 4:26am
6/30/2019 4:26am

Trax shock is a huge improvement imo for this bike. the stock shock is really good and there is no way I needed a trax but the cool factor helped me decide to try it.

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