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I just bought a brand new 2014 SX 250 2 stroke, My Ktm dealer adjusted the jets for my climate and sea level but it still fouls the plug when I start it from cold, each time I have to take the plug out, swop it for a hotter plug (7) start and clear out the the engine then swop back to the cold plug (8). Then it runs ok when engine has warmed up, can't leave the hot plug in because it burns white (too hot). I've done 15hrs total, I'm running 50:1 Motorex 2T oil, Dealer recommends 60:1 but everyone at the track said that's too lean!
I'd rather be running at 40:1 but she loves fouling plugs and I'm afraid it'll get worse at that ratio??
Any help with carb specs and float levels would be appreciated.
Thanks,
Jono
Perth, Australia.
30deg Celsius (av. Temp)
100m above sea level
 

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I just bought a brand new 2014 SX 250 2 stroke, My Ktm dealer adjusted the jets for my climate and sea level but it still fouls the plug when I start it from cold, each time I have to take the plug out, swop it for a hotter plug (7) start and clear out the the engine then swop back to the cold plug (8). Then it runs ok when engine has warmed up, can't leave the hot plug in because it burns white (too hot). I've done 15hrs total, I'm running 50:1 Motorex 2T oil, Dealer recommends 60:1 but everyone at the track said that's too lean!
I'd rather be running at 40:1 but she loves fouling plugs and I'm afraid it'll get worse at that ratio??
Any help with carb specs and float levels would be appreciated.
Thanks,
Jono
Perth, Australia.
30deg Celsius (av. Temp)
100m above sea level
Pull the slide out of the carb and you need to pull the needle out....You'll see a small C-clip on the needle...Raise it one notch up that makes the needle go down into to jet and regualates how much fuel gets dumped in ....and see if it stops fouling....and if it still fouls raise it another notch
 

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Pull the slide out of the carb and you need to pull the needle out....You'll see a small C-clip on the needle...Raise it one notch up that makes the needle go down into to jet and regualates how much fuel gets dumped in ....and see if it stops fouling....and if it still fouls raise it another notch
@ hookuspookus,
If the book is saying the second notch from the top; should I stay with that? I too am still having a problem with my bike. It was running semi okay until I pulled the throttle needle out and inspected it.
 

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@ hookuspookus,
If the book is saying the second notch from the top; should I stay with that? I too am still having a problem with my bike. It was running semi okay until I pulled the throttle needle out and inspected it.
If it says 2nd notch then start with the 2nd notch.......You mite have to adjust it to your elevation
 

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Sounds good, so how would you adjust the elevation (man this bike is killing me)!
You paid the Stealership to have this done.......First I think the main jet is too big....Look at what the stock size was and then look what they put in......Elevation is set by jet and needle hight and size ....Do you have a air mixture screw on it ? You have to play with it until you get the right combo....I'd put the needle at stock setting then get the original size jet then complain to the dealer for doing a crappy job
 

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You paid the Stealership to have this done.......First I think the main jet is too big....Look at what the stock size was and then look what they put in......Elevation is set by jet and needle hight and size ....Do you have a air mixture screw on it ? You have to play with it until you get the right combo....I'd put the needle at stock setting then get the original size jet then complain to the dealer for doing a crappy job
Do you have a guest-a-mation of how much this will cost me (elevation)?
 

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Same problem with my ktm 250sx 2014

jono i too have recently bought a brand new ktm 250sx off the floor at my local dealer. i also live in western australia too and have had the same problem you have been having since i bought the bike. there must be an issue with the 2014. if you have a break through in what to do to rectify the problem please let me know mate. also if you want to PM me on Facebook to talk about it let me know mate because I'm ****ing sick of it especially paying 10400 cash for it.
 

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Guys, I live in the south-eastern US . We are pretty warm in our spring - fall and hot in summer, always humid. Our elevation is right at 200m above sea level. When I brought my bike home, it wouldn't start either. I am an engineer by profession but I have ridden MX since my youth and have acquired the knowledge in my life to repair anything on my bikes. KTM did change the jetting from '13 to '14 but what they did is the same needle change I had to do last year. Try this jetting with a new BR8ECM plug and your problems should go away:

Verify that the main jet is 158
Change the pilot jet from a 42 to a 40 (this will lean it out when starting)
Pull the needle and verify that is says N1EH on it
Place the needle clip in the 4th position from the top of the needle
The air screw needs to be 1 1/2 turns out (the gold color screw on the lower part of the carb next to the air intake boot.

Also, running Motorex Cross Power 2T @60:1 is correct. Just make sure it's Motorex Cross Power 2T as that is what the manual specs. I thought it was too lean as well but KTM knows more about their bikes than I do. I have always had chocolate brown plugs when I check them. Remember, if you have a 300 or 250, 60:1 is correct. However a 150 and lower is NOT 60:1.

I hope this helps you out!
 

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Hi guys I also have a 2014 ktm 250 sx that fouls plugs every time it comes out the shed. I literally don't even have time to rev it and try clear it from fouling. I have put a 40 idle jet in it and lowered the float level, still no difference.
Jono and toddy north I have red your posts and was wondering if you guys have managed to overcome this issue. Cheers
Also live in Western Australia
 

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This is very strange. From what I have read and heard from others who own a '14 model, KTM changed the power delivery to come on lower in the rpm range. To do this, they redesigned the cylinder head, advanced the ignition and other mapping adjustments, changed the stock jetting, and steepened the angle of the reed block. With these facts in mind, the engine is getting more fuel at lower rpm's and therefore fouling the plugs.

I would try the following to see if this helps the problem: 1-Change the needle out from the stock N1EH to the leaner N1EI (this is what the '13 bike had in as stock). Set the needle clip 3 from the top 2-Verify the 40 pilot jet is installed 3-Set the airscrew to 1-1/2 turns 4-Mix Motorex Cross Power 2T at 60:1 and use a minimum 93 octane (95 is the spec so if you can get some racing fuel around 100 octane, add 1 gallon to 4 gallons (3.785 L 100 and 15.141 L 93) Where I live, I just use 93. The good thing about Motorex Cross Power 2T is that you can buy 1 bottle (1L or 33.814 oz.) and split the bottle into 3rds and mix with 5 gallons (18.927 L) to get right around 57:1. This makes Motorex less expensive than other premixes and it doesn't harm the KTM 250SX engine 5-Verify the air filter is clean and properly serviced

If you are still having issues, consider changing the main jet from 158 to 155. As you are trying different jetting, MAKE SURE TO CHECK THE PLUG FOR PROPER COLOR!
Go to this site,
http://www.duncanracing.com/TechCenter/KeihinCarbJetting.pdf
and download this Keihin jetting guide from Duncan. This is by far the best "how to" that I have ever read to properly jet the Keihin carb. Good luck to all of you. These things can be very frustrating.
 

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This is very strange. From what I have read and heard from others who own a '14 model, KTM changed the power delivery to come on lower in the rpm range. To do this, they redesigned the cylinder head, advanced the ignition and other mapping adjustments, changed the stock jetting, and steepened the angle of the reed block. With these facts in mind, the engine is getting more fuel at lower rpm's and therefore fouling the plugs.

I would try the following to see if this helps the problem: 1-Change the needle out from the stock N1EH to the leaner N1EI (this is what the '13 bike had in as stock). Set the needle clip 3 from the top 2-Verify the 40 pilot jet is installed 3-Set the airscrew to 1-1/2 turns 4-Mix Motorex Cross Power 2T at 60:1 and use a minimum 93 octane (95 is the spec so if you can get some racing fuel around 100 octane, add 1 gallon to 4 gallons (3.785 L 100 and 15.141 L 93) Where I live, I just use 93. The good thing about Motorex Cross Power 2T is that you can buy 1 bottle (1L or 33.814 oz.) and split the bottle into 3rds and mix with 5 gallons (18.927 L) to get right around 57:1. This makes Motorex less expensive than other premixes and it doesn't harm the KTM 250SX engine 5-Verify the air filter is clean and properly serviced

If you are still having issues, consider changing the main jet from 158 to 155. As you are trying different jetting, MAKE SURE TO CHECK THE PLUG FOR PROPER COLOR!
Go to this site,
http://www.duncanracing.com/TechCenter/KeihinCarbJetting.pdf
and download this Keihin jetting guide from Duncan. This is by far the best "how to" that I have ever read to properly jet the Keihin carb. Good luck to all of you. These things can be very frustrating.
bump this!!

My '14 250sx came set up at sea level and I live in the Rockies, and yes, I paid the dealership a "set up fee" which I promptly asked be returned....

the Duncan racing guide is awesome. Helped me out a ton, got her purrrrring real good.

The cool thing about the gear bag is that it comes with a few jets and a few needles, so you can really get her dialed in. I have had a hell of time screwing around with the power valve springs! fun to see the crazy dif b/t the green and red! I do a lot of single track and a lot of desert, so I leave the yellow in and installed a kreft power valve dial and that is sick!!!
 

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Discussion Starter #14
Hi Todd, sorry I haven't logged on for months.
How did you go with the jetting??

I changed to the RM needle NEDW(clip3 position), IJ40, MJ160, red spring...

BUT I had to replace the bottom end bearings!! Only done 40hrs on the bike so KTM agreed to do it under waranty...awesome!

She runs ok now, I'm on 49hrs.

Do you ride at Coastals?

Cheers,
 

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Discussion Starter #15
jono i too have recently bought a brand new ktm 250sx off the floor at my local dealer. i also live in western australia too and have had the same problem you have been having since i bought the bike. there must be an issue with the 2014. if you have a break through in what to do to rectify the problem please let me know mate. also if you want to PM me on Facebook to talk about it let me know mate because I'm ****ing sick of it especially paying 10400 cash for it.
Try the RM needle NEDW pos clip 3
 

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I've had problems with my 2010 fouling plugs also. Make sure you maintain a clean air filter, as a dirty filter can cause fouling
 

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I just bought a brand new 2014 SX 250 2 stroke, My Ktm dealer adjusted the jets for my climate and sea level but it still fouls the plug when I start it from cold, each time I have to take the plug out, swop it for a hotter plug (7) start and clear out the the engine then swop back to the cold plug (8). Then it runs ok when engine has warmed up, can't leave the hot plug in because it burns white (too hot). I've done 15hrs total, I'm running 50:1 Motorex 2T oil, Dealer recommends 60:1 but everyone at the track said that's too lean!

I'd rather be running at 40:1 but she loves fouling plugs and I'm afraid it'll get worse at that ratio??

Any help with carb specs and float levels would be appreciated.

Thanks,

Jono

Perth, Australia.

30deg Celsius (av. Temp)

100m above sea level


60:1 is rich not lean. It becomes leaner with more oil in which is an oxymoron I know but that’s how it is. Mate get necj 35 pilot and 165 main and your done with air screw at 1.5-1.75.


Sent from my iPhone using Tapatalk
 
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