Ktm 250 sx 2016 jetting(uk)

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4/2/2018 4:11 AM

Hi all ive been searching for over a month on jetting for my bike.i do have the necj needle and have tried this spec jetting but it runs too lean on 42p 4th clip and 175main 1.5turns out.i keep getting pinging on 1/4 throttle. Any suggestions?or people from colder climates what jetting are you running.

I have tried 45p but runs rich then but pinging does stop.

Temperatures over here range from 5c to 20c in summer .

Im considering just going back to stock settings.

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4/2/2018 4:31 AM

What fuel mix ratio are you running?
What octane fuel?
Are you the original owner?
Has the engine had a top end job done? If so, when?
What compression do you have?

Paw Paw

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4/2/2018 4:38 AM

Its near enough new its only done about 2 hours max.

98ron super unleaded mixed at 40:1

Not sure on compression its all just stock.

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4/2/2018 8:10 AM

Is there no higher 102 octane available in the uk?

Better bring the bike away and let some one listen to it and adjust it before the engine is gone.

Thought it was always 2 turns out or with a ktm 1.5 turns out?

Lol my gf cr85 is already using a main of 165 so how can a sx250 have a main of 175.. just wondering...

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4/2/2018 8:35 AM

stychey7 wrote:

Hi all ive been searching for over a month on jetting for my bike.i do have the necj needle and have tried this spec jetting ...more

Speak to Roland at Hardcore MX, he knows everything about 2 strokes.

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4/2/2018 9:43 AM

stychey7 wrote:

Hi all ive been searching for over a month on jetting for my bike.i do have the necj needle and have tried this spec jetting ...more

Muscle-Milk-KTM wrote:

Speak to Roland at Hardcore MX, he knows everything about 2 strokes.

Thanks mate ,ill give them a call . I think might try going back to a 45 pilot and 2 turns out on AS. the slight ping is only when I come in to corners on 1/4 throttle on, then clears up mid to top .Its cold here at the moment at 5 degrees which doesn't help.

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4/2/2018 2:22 PM

That bike calls for a 60 to 1 fuel mix ration and with the mix your are running the jetting is causing a lean fuel mix to the engine. Go back to the 60 to 1 and stock jetting and see if that does not cure the problem.

Paw Paw

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4/3/2018 3:27 PM

I think the oil has a lot to do also. I had the best jetting on 50:1 with castor/synthetic. I would never run synthetic/petroleum again. 250sx loves a forged aluminum piston ran way better than any other piston.
I ran 100 octane on 50:1 with a good wiseco piston and I stopped haveing jetting issues. Bike was a rocketship I miss it like a high school girlfriend.

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4/3/2018 3:31 PM

My 250sx liked only the stock needle. I changed the main jet a few times. I had what I thought was a jetting isue and turned out to be timing. Really easy to check that.

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4/3/2018 10:08 PM
Edited Date/Time: 4/3/2018 10:12 PM

I Have this setup currently in my 2016 250SX:

#170 main
#48 pilot
N1EF needle in middle position

I have ridden with this setting whole winter in Finland without any problems but I think I might have to go with #45 pilot jet when the weather gets warmer. I tried the NECJ needle too, but it was way too lean

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