2021 250 or 2021 KTM 150sx

DirtyThirty4
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Pierre Part, LA US
Edited Date/Time 9/23/2020 11:40pm
Really need help with this debate I’m having. I’m 5’5” and 155 Ibs. I currently ride a 2010 kx 250f and I love it. But I’m buying a new bike this year and I really miss riding 2-strokes. Any help or opinions would be greatly appreciated.
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Mx451
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Bozeman, MT US
7/29/2020 4:16pm
Really need help with this debate I’m having. I’m 5’5” and 155 Ibs. I currently ride a 2010 kx 250f and I love it. But I’m...
Really need help with this debate I’m having. I’m 5’5” and 155 Ibs. I currently ride a 2010 kx 250f and I love it. But I’m buying a new bike this year and I really miss riding 2-strokes. Any help or opinions would be greatly appreciated.
Hello doppelganger i am considering the very same thing. Except I'm 5'11 185lbs.
7/29/2020 4:22pm
I couldn't make up my mind so I'm planning on getting both - hopefully this weekend.
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wrc777
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7/29/2020 7:30pm
The 125/150 will have to be revved a lot more than the 250. Which way do you want to ride? The 250 has about 10 more hp, but I would think the 150 will be close to a 2010 250f.
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chump6784
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AU
7/29/2020 7:46pm
How old are you, are you still growing, what is your fitness level, what kind of riding are you doing?

I would say unless you are a vet rider that wants a play bike I would get the 250. The 250 is going to be more of a handful at first coming of a 250f but after some adjustment time you'll be fine.
If you are racing the 150 will be outgunned by the 250's and you'll be working hard to keep up and beat them.

Every now and then I take my wifes yz 125 for a spin and while its fun to ring its neck to clear jumps and just get around the track at a decent speed I could never get rid of my yz 250 for one
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The Shop

7/29/2020 7:48pm
I have an 18 250 and it's pretty badass. I'd imagine the 21 would be hard to go wrong.
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Ryan625
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Lynnwood, WA US
7/29/2020 8:29pm
I love my 17 TC250, but every time I ride a 150 I think about selling it for at least a week after...

Both is the only answer!
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7/29/2020 8:59pm
Really need help with this debate I’m having. I’m 5’5” and 155 Ibs. I currently ride a 2010 kx 250f and I love it. But I’m...
Really need help with this debate I’m having. I’m 5’5” and 155 Ibs. I currently ride a 2010 kx 250f and I love it. But I’m buying a new bike this year and I really miss riding 2-strokes. Any help or opinions would be greatly appreciated.
Mx451 wrote:
Hello doppelganger i am considering the very same thing. Except I'm 5'11 185lbs.
im 6 ft 188 pounds, and love my 150, perfect bike,
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TeamGreen
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Thru-out, CA US
7/29/2020 9:28pm
I've ridden all the new SX and TC models. Believe it or not, the 125s are faster than the 150s.
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JkopMx
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houston, TX US
7/29/2020 10:55pm
I’m 220-225Lbs. I rode a 150 for awhile . On hard pack or rutty tracks, that 150 had PLENTY to make it happen. On a few tracks I would run quicker laptimes on it than I have ridden the 450.

It is THE most fun bike I’ve ever owned , and will probally get another in the near future.
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7/30/2020 2:49am
TeamGreen wrote:
I've ridden all the new SX and TC models. Believe it or not, the 125s are faster than the 150s.
BS dude, the 150 is way faster than any 125 you can find.
Like some pro have said, riding the 150 is like riding a factory 125.
I had one for almost a year and i feel that it was competitive against 250F,
but the torque and the traction is not as good as a 4stroke.
The 250 SX on the other hand must have a lot of torque and you can ride a gear higher.
Regarding 2021 bikes, 150 are gonna be hard to find ! available in november (my ktm dealer told me this)
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kage173
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7/30/2020 4:23am
Your riding level and the type if riding are mire relevant than your weight and size.

Are you young and racing every weekend? Are you old and hitting practice days? Are A or C rider?
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DirtyThirty4
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Pierre Part, LA US
7/30/2020 6:08am
kage173 wrote:
Your riding level and the type if riding are mire relevant than your weight and size. Are you young and racing every weekend? Are you old...
Your riding level and the type if riding are mire relevant than your weight and size.

Are you young and racing every weekend? Are you old and hitting practice days? Are A or C rider?
I’m 25 and just ride for fun and might race every now and then. I’m a C rider. I rode all my life and stopped for about 10 years and just got back into it. I’ve been back riding for about a year and half now. I ride in south Louisiana. Only Mx tracks and some trails. I do however take my practice serious where I’m always trying to improve on lap times and 20-30 minute Motos. Thanks everyone for the help!
AH387
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Bridgeville, PA US
7/30/2020 6:21am
Knowing that, I'd say get the 150. I think 125/150s help make you a better rider. I think 250 2 strokes are not great at making you a better rider, but reward a skilled rider (if that makes sense lol.) The 150s are plenty fast. Since you aren't looking to race a lot then I'd get the 150. That way you have more confidence when you do race on occasion. The newer 250s are awesome, but to me they feel like a handful sometimes, compared to my own 2 personal bikes (YZ125 and FC350.) Just my opinion. Good luck.
wrc777
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7/30/2020 7:04am
TeamGreen wrote:
I've ridden all the new SX and TC models. Believe it or not, the 125s are faster than the 150s.
BS dude, the 150 is way faster than any 125 you can find. Like some pro have said, riding the 150 is like riding a factory...
BS dude, the 150 is way faster than any 125 you can find.
Like some pro have said, riding the 150 is like riding a factory 125.
I had one for almost a year and i feel that it was competitive against 250F,
but the torque and the traction is not as good as a 4stroke.
The 250 SX on the other hand must have a lot of torque and you can ride a gear higher.
Regarding 2021 bikes, 150 are gonna be hard to find ! available in november (my ktm dealer told me this)
HondaFan33
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Lawrence , KS US
7/30/2020 7:24am
TeamGreen wrote:
I've ridden all the new SX and TC models. Believe it or not, the 125s are faster than the 150s.
Could you please elaborate on this? I’m currently in the midst of the same debate. I’ve heard that the 150 doesn’t seem to pull as long but figured mods could sort that out if it bothers me.
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burn1986
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bossier city, LA US
7/30/2020 7:35am
Really need help with this debate I’m having. I’m 5’5” and 155 Ibs. I currently ride a 2010 kx 250f and I love it. But I’m...
Really need help with this debate I’m having. I’m 5’5” and 155 Ibs. I currently ride a 2010 kx 250f and I love it. But I’m buying a new bike this year and I really miss riding 2-strokes. Any help or opinions would be greatly appreciated.
I would go with the 250 with maybe a flywheel weight to smooth out the power.

The current KTM 150sx is a 125 with a big bore kit on it. The bigger piston is harder for the 125 motor to push, so it revs differently than a true 150. Before 2016, the 150 was a purpose built bike, with a different engine than the 125.

Here's the change in bore and stroke:
2015 - 56.0 x 55.84mm
2016 - 58.0 x 54.5mm

If you're looking for a purpose built 144, I would suggest the TM144mx (bore and stroke 56 x 58.2mm).




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Giraffe579
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Los Altos, CA US
7/30/2020 8:32am
At the age of 56 I bought a new 2013 150SX to save myself from dying on my '05 YZ250. Easy to ride, incredibly fun, still runs perfectly, looks awesome, and I have not died yet. Great bike.

Oh yeah - 6'3" 178lbs.
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JohnMatrix
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Irvine, CA US
7/30/2020 10:32am
I have a '17 150sx and '19 250sx. I think the 250 is by far a more versatile bike and would suggest that. The 150sx is super fun but it is more challenging to ride fast. Some days I just don't want to put in the work with that bike. As others mentioned, it's a big bore 125 and you have to ride it like a 125. Bottom end is pretty gutless on the 150 but has a huge mid-range hit. It can be tiring. The modern 250sx is really smooth and easy to ride. You wouldn't be disappointed with the 250 in my opinion.
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7/30/2020 11:44am
TeamGreen wrote:
I've ridden all the new SX and TC models. Believe it or not, the 125s are faster than the 150s.
HondaFan33 wrote:
Could you please elaborate on this? I’m currently in the midst of the same debate. I’ve heard that the 150 doesn’t seem to pull as long...
Could you please elaborate on this? I’m currently in the midst of the same debate. I’ve heard that the 150 doesn’t seem to pull as long but figured mods could sort that out if it bothers me.
It pulls enough for making it competitive against 4stroke, do you think a 40hp motor does not pulled enough? It's not because it has a 58 mm piston that you have no rev, ktm did a motor that pulls mid-range to top end with a better torque than a 125. If you really want to know just try one, it doesn't need extras, it's really powerful out if the box!
7/30/2020 11:45am Edited Date/Time 7/31/2020 7:01am
150 SX does not need a pipe, stock pipes are good, it just need a good setup with the carb and revalved suspensions...
That's a good start, riding it stock!
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IanMac138
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West Linn, OR US
7/30/2020 11:48am
My 19 150sx is a blast to ride. Lots of power and requires a lot of technique to ride it to its full potential. I race occasionally and when I'm on it, I can hold off and even pass 250f's. I'm 5'8 175lbs. Again, your technique will definitely improve on a bike that doesn't let you slack off.
IanMac138
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7/30/2020 11:53am
She's a beaut. And fast. ;-)
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skeef
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7/30/2020 12:20pm
IanMac138 wrote:
She's a beaut. And fast. [img]https://p.vitalmx.com/photos/forums/2020/07/30/441233/s1200_Screen_Shot_2020_07_30_at_11.51.50_AM.jpg[/img] ;-)
She's a beaut. And fast. ;-)
What swingarm protectors are those? I have a black frame 2020 and that looks sharp!
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kage173
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TX US
7/30/2020 12:23pm
I’m 25 and just ride for fun and might race every now and then. I’m a C rider. I rode all my life and stopped for...
I’m 25 and just ride for fun and might race every now and then. I’m a C rider. I rode all my life and stopped for about 10 years and just got back into it. I’ve been back riding for about a year and half now. I ride in south Louisiana. Only Mx tracks and some trails. I do however take my practice serious where I’m always trying to improve on lap times and 20-30 minute Motos. Thanks everyone for the help!
Go with the 150.

The 150 will be more fun and you will improve your riding at a faster rate on it. If you were racing every weekend, I'd say 250 just because of the starts, but other than that you will get more out of the 150 (you can still get decent starts on 150, but just need to be more on the ball)

BTW - I'm 5'7" - 160lbs. I own a 250SX and have ridden my buddy's 150 several times. I often think about jumping to a 150 and am likely to do so.
burn1986
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bossier city, LA US
7/30/2020 9:03pm Edited Date/Time 7/30/2020 9:06pm
TeamGreen wrote:
I've ridden all the new SX and TC models. Believe it or not, the 125s are faster than the 150s.
BS dude, the 150 is way faster than any 125 you can find. Like some pro have said, riding the 150 is like riding a factory...
BS dude, the 150 is way faster than any 125 you can find.
Like some pro have said, riding the 150 is like riding a factory 125.
I had one for almost a year and i feel that it was competitive against 250F,
but the torque and the traction is not as good as a 4stroke.
The 250 SX on the other hand must have a lot of torque and you can ride a gear higher.
Regarding 2021 bikes, 150 are gonna be hard to find ! available in november (my ktm dealer told me this)
Edited

(Double post)
IanMac138
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West Linn, OR US
7/31/2020 12:38am Edited Date/Time 7/31/2020 12:39am
IanMac138 wrote:
She's a beaut. And fast. [img]https://p.vitalmx.com/photos/forums/2020/07/30/441233/s1200_Screen_Shot_2020_07_30_at_11.51.50_AM.jpg[/img] ;-)
She's a beaut. And fast. ;-)
skeef wrote:
What swingarm protectors are those? I have a black frame 2020 and that looks sharp!
Thanks! The swingarm protectors are from Polisport. They snap on tight, and are secured with a two zip ties on each side. I remove them every few rides depending on how muddy it gets when I wash, then just snap them on and put new black zip ties in. Love 'em.

Polisport KTM Swingarm Protectors
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IanMac138
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7/31/2020 12:52am Edited Date/Time 7/31/2020 12:55am
If you buy the 150, I recommend throwing the Mikuni carb away and getting a Lectron or ANYTHING other than the POS Mikuni that comes on it. I would also recommend adding 1 tooth to the rear sprocket (stock is 48 so go to 49) along with the Moto Tasinari V Force 4 reed valve system.

I put a Lectron on my bike and have never looked back...gave more low end torque and spread out the power. Adding 1 tooth to the rear sprocket allows me to carry tighter corners in 3rd gear with a slight feather of the clutch if needed before the afterburners kick in. The 48 tooth had me shifting down to 2nd in tight corners, which made me have to blow through 3rd and click to 4th on jump faces. Not fun. Now I can lug it in 3rd, feather the clutch and click to 4th before a jump face with ease.

Lastly, I recommend the FMF 2.1 Powercore silencer and FMF pipe. This combo, along with the Lectron and V4 reed cage made my bike bark, never bog and straight up changed the power delivery from the stock. She sounds like a screaming dragon and runs super clean. Oh, and I run 50/50 clear 92 octane with VP 110. She rips.

Cheers.
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goose1229
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Syracuse, NY US
7/31/2020 5:10am
I've got a '17 150 and have had 250 two strokes in the past. By far the 150 is the most fun bike I have ridden. Do you actually have to ride the bike? Yes. So if you don't want to shift all that much then the 250 two stroke would be a better fit. From cornering to jumping I feel like I hit everything harder and faster on the 150 because you can man handle the bike vs. the bike getting away from you.

In regards to the carb and jetting, there are some awesome specs in the race shop section of the forum which clean up the mikuni carb. I have a full PC exhaust system, Vforce 4R reeds and followed the jetting set up to a T and the bike screams with no hiccups at all. The bike sounds like a factory machine running 100 octane pump gas.
AJ565
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San Antonio, TX US
7/31/2020 6:23am
IanMac138 wrote:
If you buy the 150, I recommend throwing the Mikuni carb away and getting a Lectron or ANYTHING other than the POS Mikuni that comes on...
If you buy the 150, I recommend throwing the Mikuni carb away and getting a Lectron or ANYTHING other than the POS Mikuni that comes on it. I would also recommend adding 1 tooth to the rear sprocket (stock is 48 so go to 49) along with the Moto Tasinari V Force 4 reed valve system.

I put a Lectron on my bike and have never looked back...gave more low end torque and spread out the power. Adding 1 tooth to the rear sprocket allows me to carry tighter corners in 3rd gear with a slight feather of the clutch if needed before the afterburners kick in. The 48 tooth had me shifting down to 2nd in tight corners, which made me have to blow through 3rd and click to 4th on jump faces. Not fun. Now I can lug it in 3rd, feather the clutch and click to 4th before a jump face with ease.

Lastly, I recommend the FMF 2.1 Powercore silencer and FMF pipe. This combo, along with the Lectron and V4 reed cage made my bike bark, never bog and straight up changed the power delivery from the stock. She sounds like a screaming dragon and runs super clean. Oh, and I run 50/50 clear 92 octane with VP 110. She rips.

Cheers.
Man, thats a bit harsh on a really good carb just because you don't know how to jet it.

Everyone I know that put a Lectron on for moto took it back off because it deadens the hit and doesn't pull as hard.
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mxstate
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8/28/2015
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FL US
7/31/2020 6:49am
AJ565 wrote:
Man, thats a bit harsh on a really good carb just because you don't know how to jet it. Everyone I know that put a Lectron...
Man, thats a bit harsh on a really good carb just because you don't know how to jet it.

Everyone I know that put a Lectron on for moto took it back off because it deadens the hit and doesn't pull as hard.

What he says...
I had a 17 TC250 that I couldn’t figure out because only worked with Keihin in the past. Threw one in the bike and it worked fine , ($300 + later)
Got a 19 after a failed experiment with a 250SXF.
Stock jetting was much better but yet not what I was expecting. Came across AJ thread, got in touch with him and he put me in the right direction.
Slide is cheap change and you can even modify the OEM.
I am super happy with the way the TMX runs now.
No more erratic behavior during the day with temp/humidity changes. No more gargle low/mid
I know that some mags have been bashing hard the Mikuni, I saw JA 21 TC 250 fitted with the Keihin but I’m no JA21.
All choices are valid as long as set up properly.
I rode a husky 125 with a lectron and was not blown away.
The Mikuni has been on the YZ125 for quite some time and I don’t recall any drama about the way that bike runs.

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