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2012 250 sx detonating

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I got this bike a couple weeks ago and i noticed that it has a very low amount of detonation when i barely crack the throttle at low rpm and also WOT at high RPM.

Midrange feels perfect. The carb is still in its stock setup, i haven't touched anything. I do most of my riding in north Texas (about 400 feet above sea level). I use 93 octane (up to 10% ethanol) with maxima 927 castor at 40:1.

I'm thinking of going up one size on the pilot jet and one size on the main. what do you guys think?

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I would start buy talking to my local dealer's crew.I happen to have the best group of wrench slinger's at my local KTM dealer,3 guy's who just plain get it figured out and fixed.Talk to them first,they know what work's and what to do to fix your problem,Im sure they all ride and they hear all the skinny behind the scene's stuff that us mere mortal's don't have access to.My 2 cent's.........

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On my 2012 250sx I went with the rich needle # N1EH and the main jet I went to a # 160.

I run 93 mixed 40:1 Maxima Super-M

Runs good and clean no black oil out the back tail pipe and plug is light tan.

I ride in Fla. If that helps.

Ron.

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Just got mine this week, put 2 track days on it or about 2 1/2 hours. Mine was rich in the pilot and was loading up so I went to the 40 pilot (42 stock) and now it is very crisp. Also went to a 160 main, left the needle stock. Mine never pinged on WOT but does sound like it is pinging at idle. I'm now running a 50/50 mix of pump and 104 sonoco gt plus. It still has a slight pinging type sound but not as bad, I've come to the conclusion that this is how it sounds. Been riding 4 strokes too long. LoL

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All the modern 2 strokes that I've encountered when ridden hard on today's crap gas will ping some.

I had to add 30-50% leaded race fuel to my 100% stock '08 250SX for instance to prevent it.

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Buy a few richer sizes for your main and pilot. Should do the trick.

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I haven't changed anything yet but i went riding today and it was really cold outside about 40 degrees. the bike sounded like it was pinging more than usual. I'm going to take KJ55's advice and buy a few main and pilot jets and swap some brass. I'm not going to mess with the needle or clip just yet.

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MXA Test says you will need to go to a 160 or 162 Main and up one on the pilot if you are close to sea level.

You can alway's use the great little chart they have in the owners book. It's easy to figure out and usually spot on.

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i went with a 160 main jet and a 45 pilot. i also used the richer NE1H needle with the clip at position 4. i went out two turns from fully closed on the air screw. i rode the bike in a field and it feels ok but all the tracks rained out this weekend so i'll have to wait to post results.

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Im also in texas here, Ive only ridden once at rivervalley on my new bike. I have a 160 mj, 42 pilot, ne1h, 4 position, 1 1/2 air screw, 50:1 lucas semi-synthetic with iridium plug. ran great but didnt really do too much aggresive testing as I was breaking it in. Interested to hear about your results as soon as possible. Thanks

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I had the same issue on my 2008 250XC-W. I took it in to SMS racing to have them take a look. After linstening to the bike they suggested that I go up one size pilot. The stock on my bike is a 35 and the suggestion is to go to a 38.

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The first thing I would do other than jetting is buy some super M oil or anything other than the 927!

Yes I love the smell of castor oil too! But it makes a ton of carbon and will eventually cover the exhaust valves and can plug up the silencer.

super M is cleaner and cheaper! Just doesn't have that beautiful smell!

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Funny thing is i actually bought the bike from SMS and the tech told me to just run half race gas and half regular gas. I'm on a budget so richer jetting it is.

So far i've ridden at Underground MX twice and i rode at I-35 (gnarly sand track) when it was 38 degrees outside and the bike ran perfectly.

@kx137 i'm guessing you're pretty close to where i'm at, are you also riding a 250sx?

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The first thing I would do other than jetting is buy some super M oil or anything other than the 927!

Yes I love the smell of castor oil too! But it makes a ton of carbon and will eventually cover the exhaust valves and can plug up the silencer.

super M is cleaner and cheaper! Just doesn't have that beautiful smell!

yea i noticed my silencer is spooging a little bit. i've never experienced that with any bike i've owned. this is the first time i'm trying the castor oil. I bought the 1/2 gal jug so i'll use that up and buy something else.

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Does anybody use Amsoil ?

I ran it in my 200 for 3 year's,Never fouled a plug and powervalve and top end were spotless!!!I just mixed my 1st batch for the new 250sx,Gonna get Friday and Saturday to ride it!!Calling for 54 degrees and sunny,sorry to wander....Amsoil is good stuff!!:bonk:

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Amsoil dominator is all I use...
I ran it in my 200 for 3 year's,Never fouled a plug and powervalve and top end were spotless!!!I just mixed my 1st batch for the new 250sx,Gonna get Friday and Saturday to ride it!!Calling for 54 degrees and sunny,sorry to wander....Amsoil is good stuff!!:bonk:

Are you guys running the recommended 50:1 ratio or something else?

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Are you guys running the recommended 50:1 ratio or something else?

i think the manual for my 250 says 60:1 but i do 40:1. i get a feeling that the motor won't like so little oil running through it.

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