13 KTM 250SX Jetting Help

Barnett117
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Barnett117
Edited Date/Time 2/13/2015 5:40am
I saw this post and got some good starting info:

http://www.vitalmx.com/forums/Moto-Related,20/2013-KTM-250-SX,1241842?p…


42 pilot
172-175 main
1.5 turns out on the air screw
3rd clip on a NECJ needle

My question is will this work at aprrox 700ft above sea level? I run good pump gas (93 octane), should I mix it 32:1 or 40:1?

The bike has FMF Fatty and FMF shorty.

Any help would be great!
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Paw Paw 271
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Paw Paw 271 2/11/2015 4:44pm
2/11/2015 4:44pm
The only way o know for sure is to perform chop test and do plug readings.

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swtwtwtw
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swtwtwtw 2/11/2015 6:16pm
2/11/2015 6:16pm
On my 2014 Husky....sea level to 2300'
50/50 gas at 44:1
165 main
stock needle 3rd clip
42 pilot
air screw 2 turns

Great plug readings and runs like a 2-stroke ought too. It will pull 3rd gear starts off concrete with stock gearing and revs to the moon.
digger
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digger 2/11/2015 6:45pm
2/11/2015 6:45pm Edited Date/Time 2/12/2015 2:27am
Barnett117 wrote:
I saw this post and got some good starting info: http://www.vitalmx.com/forums/Moto-Related,20/2013-KTM-250-SX,1241842?page=1 42 pilot 172-175 main 1.5 turns out on the air screw 3rd clip on a...
I saw this post and got some good starting info:

http://www.vitalmx.com/forums/Moto-Related,20/2013-KTM-250-SX,1241842?p…


42 pilot
172-175 main
1.5 turns out on the air screw
3rd clip on a NECJ needle

My question is will this work at aprrox 700ft above sea level? I run good pump gas (93 octane), should I mix it 32:1 or 40:1?

The bike has FMF Fatty and FMF shorty.

Any help would be great!
I would start out with an NECW needle, which is a little richer than the NECJ. A 40 pilot and 172 main would be close for warm weather settings. I would go 42-45 and 175/178 for colder weather. I like to start out with a W series needle in the 250's and a J in the 300's.
swedishfishmx
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swedishfishmx 2/11/2015 9:34pm
2/11/2015 9:34pm
I always found the manual to be a helpful start. At least it gives you a good base setting.

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Fearo
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Fearo 2/12/2015 1:08am
2/12/2015 1:08am Edited Date/Time 2/12/2015 1:11am
swedishfishmx wrote:
I always found the manual to be a helpful start. At least it gives you a good base setting.
Yeah, that's a no for KTM's though Smile . What's the stock jetting for a 250SX...155 main or something like that? Not a good base setting at all. My 2008 SX 150 came stock with something like a 175 main and we went to a 230(!) and it still wasn't rich. I remember those bike just grenaded after 10-15 hours on the stock jetting.

I would go with Digger's advice. See if it can pull a 45 pilot and stay over 170 on the main. Can't help you with the finetuning because I'm at sea level, but you'll figure it out.
Barnett117
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Barnett117 2/12/2015 9:13am
2/12/2015 9:13am
Thanks guys. What should I run my fuel at? I race woods and probably wont be wide open all the time. I mixed my 2012 150SX at 32:1 and got 50 hours out of a top end and ran great.
swedishfishmx
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swedishfishmx 2/12/2015 4:18pm
2/12/2015 4:18pm
swedishfishmx wrote:
I always found the manual to be a helpful start. At least it gives you a good base setting.
Fearo wrote:
Yeah, that's a no for KTM's though :). What's the stock jetting for a 250SX...155 main or something like that? Not a good base setting at...
Yeah, that's a no for KTM's though Smile . What's the stock jetting for a 250SX...155 main or something like that? Not a good base setting at all. My 2008 SX 150 came stock with something like a 175 main and we went to a 230(!) and it still wasn't rich. I remember those bike just grenaded after 10-15 hours on the stock jetting.

I would go with Digger's advice. See if it can pull a 45 pilot and stay over 170 on the main. Can't help you with the finetuning because I'm at sea level, but you'll figure it out.
That can't be right....230 for a main seems way too big, but what do I know.

I did go a little bigger on the main on my TC and went with the RM Needle and a 45 pilot for most weather conditions.

Fearo
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Fearo 2/13/2015 5:40am
2/13/2015 5:40am Edited Date/Time 2/13/2015 5:42am
I know, Swedishfish, 230 main seems crazy but that's the only way those bikes ran well. Me and a bunch of guys had to place a special order somewhere because no one even stocked 230s!

Keep running your fuel at 32:1 Barnett. I have been running that ratio in KTM's for 10 years in 125s, 150s and 250s with zero problems. If it smokes a lot or gets very greasy at the exhaust tip try leaning it out to 40:1 but I suggest you start with 32:1 and see how it goes. I have zero woods experience so it might be a little rich.

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