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Suzuki needle help

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Hello everyone, I have a 2011 250xc with the W trans gears swapped into it. It has a 2014 cylinder, cycle playground modded new style sx head at .045" squish, sx cdi,stock pipe and silencer and v force 4 reeds. I am running 50-1 pump fuel mix at sea level and app 80°.

Fresh top end with vertex piston.

 

Long story short I went from a lectron back to stock carb and a jd kit. I tried all I could with the jd kit with blue needle and could not get rid of a off idle sputter.

I called and emailed jd Friday but have not heard back. I put a nedj needle in that I had and the sputter immediately went away. Problem is it is lean on deceleration and pinging on loaded acceleration and deceleration. The pinging may be a octane issue I am thinking but also may be because it is lean. I am running a 40 pilot with a 165 main and the nedj needle on the third clip. I am thinking of trying some richer needles like a nech or nedh. Am I on the right track ? A lot of you guys seem real knowledgeable on the suzuki needles. Any help is appreciated.

Thank you everyone.

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It sounds right but try better fuel first off , make sure the pipe is sealed well at the cylinder and mid conection, if that don't help a NECJ might help or NEDH  might do it. 

Try a 42 pilot before any more needles You will want to get richer on the last or second to last # maybe both if the 42 don't cure it

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How, what method, are you tuning the air screw? Use the "whack the throttle" method. If the air screw dials in with best throttle response off idle, less than 1 turn out, go to a 42.

If you change the needle, retune the air screw.

The 2nd from last digit is the general needle taper. Going higher in the alphabet is richer. The last digit is needle starting taper. Going higher in the alphabet is leaner. Starting taper is the one that interacts with the pilot system and controls transition between the two. The difference between adjacent letters is 1/2 clip position, meaning that, if you were to go to an nech from your nedj, keeping the same 3rd clip position, that move would result in an equivalent change of 1/2 clip position "leaner" for the overall taper because you dropped 1 letter and a change of 1 whole clip position "richer" for the starting taper because you dropped 2 letters.

So what octane are you running? Sounds like you've modded the head for high compression. You may have modded yourself out of the ability to run pump gas. I think the highest pump gas I've seen at stations near sea level is 95.

I'm thinking your main is probably fine at a 165.

Edited by Trailryder42

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44 minutes ago, Trailryder42 said:

 

The 2nd from last digit is the general needle taper. Going higher in the alphabet is richer. The last digit is needle starting taper. Going higher in the alphabet is RICHER

Hey 42 I agree mostly but going higher in alphabit is going leaner...

It's debatable if starting diameter or or taper or fuel is the cause here of the problem, I would guess if it's not fuel and when he says roll off its a full roll off then it's pilot size or starting diameter. If his roll of is partial then I guess it's needle taper or clip position. Suzuki needles like a big pilot jet in my experience,

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9 minutes ago, peaceofwork said:

Hey 42 I agree mostly but going higher in alphabit is going leaner...

 

You edited my quote, then contradicted yourself.

Here's a chart that verifies my statement.

post-60022-0-74509600-1363838106.jpg

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Thank you for all the info so far ! The head mod was supposed to be ok on pump gas but I am doubting that now. I plan to get a few gallons of 100 or 110 octane to try. I am sure the aggressive sx cdi doesn't help the pinging either. If I have to mix some race fuel say 50/50 with pump fuel I am ok with that. 

With the 40 pilot I am out 2 turns on the air screw to have it run clean off idle. That was as of yesterday on a app 85 degree ride. If it's turned in anymore than that it will sputter right off idle. The bike is street plated so I ride it to the trails. The off idle sputter drives me nuts on the road. 

So if I understand correctly a nech needle would make it leaner on the pilot but richer on the transition ? I am kind of confused because a nech shows richer than a nedj. I understand the C being leaner than the D but H is before J. What am I not getting here lol?

So maybe try the nech and see if I can get my air screw turned in and see if it fattens it up on the decel ? Or am I better of trying a nedj with a 38 pilot ?

I did try raising the nedj to the fourth clip but I could not get the off idle throttle response to clean up with the air screw so I went back to the third position. I am setting the air screw by the throttle response off idle. 

Edited by horsinaround

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1 hour ago, horsinaround said:

So if I understand correctly a nech needle would make it leaner on the pilot but richer on the transition ? I am kind of confused because a nech shows richer than a nedj. I understand the C being leaner than the D but H is before J. What am I not getting here lol?

Look at the last digit. It represents the starting taper. Higher up the alphabet for the last digit is leaner, not richer like it is for the 2nd to last digit. So, J is leaner because it comes after H in the alphabet. It's confusing, I know. Get this, W takes the place of I. :banghead:

Look closely at the chart. Follow the last digit of the needles from richest to leanest and you see the alphabet goes up from F to L.

Then for each needle series, you have a 2nd digit variation of that series, C and D,  that represents the needles general taper. The D variation is richer the the C variation.

Just remember:

2nd from last digit, higher in the alphabet = richer

last digit, higher in the alphabet = leaner

The needle doesn't effect the "pilot" system except for that very small overlapping area where the pilots influence starts to drop off to nothing, and the needle starts to take over and move into the midrange; that's the starting taper, represented by the last digit. Get that dialed in first. Then determine if the general taper, C and D variations, that run the midrange and on into the main jets range is right or not.

When I put the Suzuki needle in my carb, I bought 9 different needles. Spent all day one day taking notes and swapping out needles and clip positions to find the best tune. Keep in mind, adjacent needles(C to a D, or J to K) are only 1/2 clip position in size difference. Imagine you had a needle on the 3 position and you wanted to move to a richer position but you think a whole clip position would be too much. You can't make 1/2 position moves with the clip. So you move to an adjacent needle in the chart. Putting the clip in the same 3rd position as the old needle gives you that 1/2 clip position difference that you couldn't make with the old needle.

You may not need to tune so precisely to get performance acceptable to you.

 

 

 

Edited by Trailryder42

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hey 42 no offence intended looks like i better reread it, i was thinking nech would be richer than necj ? and the farther down the alphabet you go the leaner you get ? and ya i had messed up on the quote

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40 minutes ago, peaceofwork said:

hey 42 no offence intended looks like i better reread it, i was thinking nech would be richer than necj ? and the farther down the alphabet you go the leaner you get ? and ya i had messed up on the quote

I guess it depends on what "UP the alphabet and DOWN the alphabet" mean to you. I take it as, toward A is DOWN the alphabet and toward Z is UP.

nech WOULD be richer than necj, on the "starting taper"

Want a headache, head over to KTM Talk and read the great sticky on Suzuki needles.

Edited by Trailryder42
  • Like 1

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Just to follow up with this thread. I currently have a nedw needle in the bike and it is working pretty darn good so far. Almost perfectly clean off idle but slightly rich mid range. I went back to a lectron for awhile but couldn't get it to run as clean as I wanted. I threw the pwk back on tonight. I also now mix 50/50 92 octane pump gas and 110 octane cam 2 race fuel. I mix a 50-1 ratio of golden spectro.

 

 

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