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2001 RM250 NECJ needle info?

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Not really sure what specific question to ask here, but basically I have been trying to educate myself on Suzuki's NECJ needle that everyone loves so much, but can't find any specific info (like what year RM's used that needle, what main/pilot/power jet sizes they ran with it, etc...). My 01 RM250 runs great, but spooges a ton. Seems to be rich under 1/2 throttle, but fine above 1/2 throttle. Idle screw is happy at 1 1/2 turns out so I believe my pilot is tuned correctly. Here's how I'm jetted currently:

Main - 155 (stock is 162)

Pilot - 45 (stock is 48)

Needle - Stock (N3WK), 2nd clip position

Power jet - Stock

Idle screw - 1 1/2 turns out

So basically I was wondering:

1) Would it be worth it to swap to the NECJ needle?

2) If so, what jetting should I start at? Don't know what other RM's ran that needle to compare to, and I'm afraid to accidentally run too lean.

Like I said, the bike runs great, but I feel like any leaner on the jetting and I'll be fine down low, but too lean up top. I guess I'm just looking for pros and cons before I decide to mess with it further.

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answer is yes worth the swap and they are from a 2004-2008 rm250 

part no. 

13383-37FE0 NEEDLE,JET(NECJ

if you ride in high temps like i do i would get the neDj and run clip 2

part no.

Suzuki 13383-37FM0 - NEEDLE, JET (NEDJ)

leave your pilot and main 

the ne needle will be the same as your n3 1/2 throttle to wot

Edited by kxrob
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Thanks so much, I appreciate the info. To clarify a little further, I do ride at mostly high temps (I want to say 70-90 degrees on average), at usually around 3-3500 feet. High desert of southern california, so it's hot most of the year, but gets quite cold during the middle/end of winter. So is the NEDJ a leaner needle than the NECJ? And are the NECJ/NEDJ needles leaner than my N3WK? Or is it more complicated than that? Sorry for the 20 questions, trying to learn as much as possible. If the NECJ/NEDJ is better, I'd like to know why.

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leaner clip position then the xxWx needle you got but in a good way as the xxWx needle you got is really rich 1/4 -1/2 throttle

difference between a xxCx needle and a xxDx needle is 1/2 clip position , the xxDx is actually 1/2 clip rich in same clip postion for example clip 3 , but if you run the xxDx in clip 2 it is the same as xxCx in clip 2.5

if you ride at 3000-3500 ft and in that temp range you might get away with a necj in clip 2

get both ( they are cheap ) and try them

the j in the needle code is a little bit rich then the k in you original needle but not by much , so slightly safer at 1/4 throttle

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If you search the subject there are a lot of posts that you can pick up some extra info from. The needles are only leaner (or richer) in the first, or top, of the needle. I've attached a pic to help, it's fro the Suzuki service manual.

ps: unfortunately many needle are no longer available. Search Google for them, you'll get JD Jetting, Jets are Us and a couple others I think. 

image.jpg

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Hey guys. I don't mean to resurrect an old thread, but I finally decided to pull the trigger on the NECJ needle swap, and figured I'd post here instead of starting a new thread for a small update.

So I swapped my N3WK needle for the NECJ, left all my current settings exactly the same. Riding at about 3000 feet, warm weather at 70 degrees or so. Honestly couldn't tell too much of a difference at first, but after a bit of riding I did notice some change. It seems a bit cleaner and snappier right where I expected it, at about 1/2 to 3/4 throttle. Very subtle, but noticeable. Still feels identical right off the bottom, and at 3/4 to WOT. I also noticed it spooged much less. It is definitely still a tad on the rich side, but I think with a bit more fine tuning it will be as good as I will ever need. The thing screams, I'm really just nit-picking at this point.

Just wanted to share my experience in case anyone else was considering swapping to the NECJ. Was there a drastic difference? No. Was it worth the swap? Yes. At least for my bike and my riding conditions.

 

20181007_153836.jpg

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8 hours ago, criggs88 said:

Hey guys. I don't mean to resurrect an old thread, but I finally decided to pull the trigger on the NECJ needle swap, and figured I'd post here instead of starting a new thread for a small update.

So I swapped my N3WK needle for the NECJ, left all my current settings exactly the same. Riding at about 3000 feet, warm weather at 70 degrees or so. Honestly couldn't tell too much of a difference at first, but after a bit of riding I did notice some change. It seems a bit cleaner and snappier right where I expected it, at about 1/2 to 3/4 throttle. Very subtle, but noticeable. Still feels identical right off the bottom, and at 3/4 to WOT. I also noticed it spooged much less. It is definitely still a tad on the rich side, but I think with a bit more fine tuning it will be as good as I will ever need. The thing screams, I'm really just nit-picking at this point.

Just wanted to share my experience in case anyone else was considering swapping to the NECJ. Was there a drastic difference? No. Was it worth the swap? Yes. At least for my bike and my riding conditions.

 

20181007_153836.jpg

AWESOME pic for sure!

What tires you runnin on your 250?

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Sounds about right. 

You do know that the last digit on these needles are the starting diameter which affects your 1/8-1/4 throttle position. Swapping a K diameter to a J you actually went RICHER 

Which throttle slide is in your carb? 

I suspect it’s a 6 or 6.5 since you had a K diameter needle to begin with.

Not cheap, but I would recommend a #7 slide and a NEDK needle for your elevation if the NECK is too lean going to clip 2

One thing most guys don’t consider is the needle jet (jet that needle drops into) wears with time.  Unfortunately this is not a replaceable item. The wear can be compensated for by running a larger starting diameter in older worn carbs. 

 

Edit;

Another thing is the RMs that use the NECJ needle came stock with a 168 main. The taper or tip of the needle changes which main jet is used. I would be stepping that up to no less than a 160. 162-165 should be about right at your elevation. 

When the YZ 250 guys use this needle they are swapping the 178 mains that they use with the thicker tip YZ needles for 168 mains suitable for the thin tipped Suzuki needle. 

Edited by Jeremyf1
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3 hours ago, Jeremyf1 said:

One thing most guys don’t consider is the needle jet (jet that needle drops into) wears with time.  Unfortunately this is not a replaceable item. The wear can be compensated for by running a larger starting diameter in older worn carbs. 

 

Edit;

Another thing is the RMs that use the NECJ needle came stock with a 168 main. The taper or tip of the needle changes which main jet is used. I would be stepping that up to no less than a 160. 162-165 should be about right at your elevation. 

Yeah, I figured this bike ran so rich originally because of this. I am down all the way to 155 main and 45 pilot, with the needle in 2nd clip, and it was still obviously rich at anything between 1/4 and 3/4 throttle. That's the main reason I swapped needles, because at WOT it's pretty dead on, and the air screw was set dead at 1.5 turns out for my pilot circuit, yet I was still rich in the middle. That's kinda what I meant when I said I have to a little more fine tuning. My hope was that the needle would only lean out 1/4 to 1/2 throttle range, and that being slightly richer off bottom I can correct with a smaller pilot if need be. Next time I go out I'll recheck the air screw and do another plug chop and see exactly where I'm at. Thanks for the additional info.

 

4 hours ago, ar2stroke said:

AWESOME pic for sure!

What tires you runnin on your 250?

 Thanks, haha, that was a tough one to get. The wind was blowing like crazy up there. Right now it has an old Maxxis Maxxcross IT 120/90R19 in the back that I am about to swap with a Shinko 505 Cheater 110/90R19. Heard some good things about it and couldn't afford much more, so figured I'd give it a try. I'm honestly not sure what exactly is in the front other than a Michelin that also is in need of a change =P.

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Yes you can rob a little off Peter to pay Paul, but only up to a point. Going to a smaller pilot is basically the same as opening up your air screw 1/2 turn. My 2000 RM had the same needle as you, but a #6 slide.

It also had the choke/Idle setup like the old PJs did. Terrible carb.... 💩 canned that carb and installed a 07 RM 250 carb with the #7 slide and NECJ needle I got from eBay. Sooo much better!!!

Son has the bike now... We ride mostly at sea level so the J diameter worked perfect. 

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Yeah, good point. I'll do some fine tuning and see how it goes, if it still seems like it needs more I'll try the NECK and see how it feels. I knew it'd be 1/2 clip richer at 1/8 throttle, but I was worried it might lean me out too much elsewhere, so I felt safer with it a tad richer off bottom. Like I mentioned it actually feels identical below quarter throttle and above 3/4, didn't notice any change at bottom or top. I just hope I'm on the right track =P.

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I always tune from the bottom up. Your pilot and air screw setting is a bit richer than what we ran here in Washington at sea level, so it’s got to be rich for you with the elevation and temps. 

When was the last time your crank seals were replaced?

Pretty sure the ‘01s got a 6.5 slide, so that’s also richer. You’ll have to check the # on the bottom of your slide...

Something to consider when you doing the plug chop tests is that if your getting spooge at  low throttle positions, that means your plug is running black. All your really seeing is how much of that is getting burned off... Your way better off fixing the low throttle position issues before choosing your main.

Ya gotta figure the RM was jetted for motocross. Not trail riding. For MX rich slides and starting diameters help get the fuel moving while throttle transitions from closed to wide open. Better throttle response. Not the best for trail riding. 

Personaly based off my ‘00 I’d be running a 42 pilot, NEDK #2, #7 slide, or you could try a NEDL with the 6.5 slide(heck buy them both), and bring that main up. 162 would be a good one to try. It’s always good to be a tad rich WOT for that extra bit of safety margin...

Edited by Jeremyf1

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On 10/8/2018 at 5:14 PM, criggs88 said:

Hey guys. I don't mean to resurrect an old thread, but I finally decided to pull the trigger on the NECJ needle swap, and figured I'd post here instead of starting a new thread for a small update.

So I swapped my N3WK needle for the NECJ, left all my current settings exactly the same. Riding at about 3000 feet, warm weather at 70 degrees or so. Honestly couldn't tell too much of a difference at first, but after a bit of riding I did notice some change. It seems a bit cleaner and snappier right where I expected it, at about 1/2 to 3/4 throttle. Very subtle, but noticeable. Still feels identical right off the bottom, and at 3/4 to WOT. I also noticed it spooged much less. It is definitely still a tad on the rich side, but I think with a bit more fine tuning it will be as good as I will ever need. The thing screams, I'm really just nit-picking at this point.

Just wanted to share my experience in case anyone else was considering swapping to the NECJ. Was there a drastic difference? No. Was it worth the swap? Yes. At least for my bike and my riding conditions.

 

20181007_153836.jpg

You running clip 2 ?

 

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Yup, 2nd clip position. I tuned from the bottom up, as well. I'm running the pilot circuit the way it is because it idles best at 1.5 turns out. I always assumed that was how the pilot was tuned. With the original 48 pilot, it needed to be at 2.5/3 turns out, so I dropped it down to the 45 pilot, and it was dead on at 1.5 turns. Wouldn't I start going too lean if I went any lower? Also I ride mostly above 1/2 throttle, and I was getting spooge dripping down off the bottom of the silencer by the end of a single hour long ride, and it was super sputtery at 1/2 to 3/4 throttle. The NECJ has helped quite a bit, but it still seems a tad on the rich side, even with the 155 main still in it. I'll definitely consider the NECK, but it really seems pretty damn close as it sits now. Also, according to my service manual, I've got a #7 slide.

The bike came with a 160 main (stock is 162), and it ran extremely rich. 

As far as crank seals, I was told by the PO that engine was rebuilt and had about 10 hours on it. I've put probably 20 hours on it since. The bike does not consume any gear oil, at least not enough to notice between regular oil changes.

Like I said, next time I go out I'm going to re-dial the pilot and see where it's at with the new needle. Throttle response and snap off the bottom seems fantastic, so I can't imagine it's far off.

Edited by criggs88

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17 hours ago, criggs88 said:

Yup, 2nd clip position. I tuned from the bottom up, as well. I'm running the pilot circuit the way it is because it idles best at 1.5 turns out. I always assumed that was how the pilot was tuned.

Correct. The ideal pilot has your air screw 1-1/2 turns out

With the original 48 pilot, it needed to be at 2.5/3 turns out, so I dropped it down to the 45 pilot, and it was dead on at 1.5 turns.

Now this sound odd to me. Typically a jet change of one size changes your air screw setting 1/2 (+ -) turn. A change of 1 to 1-1/2 turns leads me to suspect you may have a air leak that got worse at the time you changed jets, or you bought one of the clone Keihin jets. Genuine Keihin jets have a “K” on them before the #

Wouldn't I start going too lean if I went any lower?

Yes you would, but the affect is at mostly idle position. When you said you would lower your pilot the lean out your 1/4 throttle positions my suggestion was try opening up your air screw and try it. Air screw and pilot affect idle A/F ratios. You’ll find the affect at 1/4 throttle is little to none... Same as changing clip position. Clip affects primarily 1/2 throttle and the affect of this obviously bleeds over to the straight diameter, and needle taper. It’s not always that simple and things can get confusing when dealing with different multiple taper needles vs the old single taper needles...

Also I ride mostly above 1/2 throttle, and I was getting spooge dripping down off the bottom of the silencer by the end of a single hour long ride, and it was super sputtery at 1/2 to 3/4 throttle. The NECJ has helped quite a bit, but it still seems a tad on the rich side, even with the 155 main still in it. I'll definitely consider the NECK, but it really seems pretty damn close as it sits now. 

Well if your happy with your present jetting, then I’m happy.  Was just trying to make suggestions that would make it run even better. I would have never suggested running a larger straight diameter when you said your low throttle positions were too rich. Step in the wrong direction if you ask me..

The bike came with a 160 main (stock is 162), and it ran extremely rich. 

The main your bike came with is irrelevant when you change needles. As I said earlier the RMs that use the NEC(X) needles came with a 168 so you should be choosing your main based off the NEC(X) series needle, not the N3 series. 

Main affects your WOT and has (depending on needle) very little affect at 3/4 and below. You shouldn’t be changing a main to correct a 3/4, or any other throttle position problem other than Wide open.

Also, according to my service manual, I've got a #7 slide. 

I would be checking what # is on the bottom of your slide. Parts micro fisch says otherwise. The 37F00 slide is shown to only be used in the 01-02 RMs. If it was the same as the 37F80 #7 slides used on the 05-08 it would be the same part number, and shown to fit the 05-08s too...

As far as crank seals, I was told by the PO that engine was rebuilt and had about 10 hours on it. I've put probably 20 hours on it since. The bike does not consume any gear oil, at least not enough to notice between regular oil changes.

Unless Previous owner is someone you know, I’ve found PO’s can’t be 100% trusted...

Like I said, next time I go out I'm going to re-dial the pilot and see where it's at with the new needle. Throttle response and snap off the bottom seems fantastic, so I can't imagine it's far off.

Going back to a K diameter is going to basically the same as the K you pulled out. Just off idle throttle position will be the same. Now since the tapers are totally different, obviously everything in between 1/4-3/4 will differ (for the better with the NE needle), but if I were looking to clean up low throttle jetting I’d go with the larger straight diameter.

Sounds to me like you have a 6.5 slide, or a really worn needle jet..

Happy trails!!! Brapppp :ride:

 

Edited by Jeremyf1
Damn autocorrect lol
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On 10/12/2018 at 2:44 PM, Jeremyf1 said:

 

Ok, so this definitely helped clarify something that I didnt realize. I appreciate you taking the time to go into more detail. Ive always been comfortable adjusting jet sizes, but im totally new to swapping needles. The only reason I tried the NECJ is because I've heard good things about it.

Off the bottom the bike FEELS good. I am definitely going to recheck my pilot circuit next time I go out just to be certain.

My big question at this point is: should I stick with the NE needle for now, or should I go back to my old N3? 

I do trust the PO, I do not suspect any air leaks at this point.

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No the NECJ is a great needle.... When used with #7 slide, 45 pilot, 3rd. clip, 45-50 powerjet, and 168~ main, at or close to sea level, with average temps 70F~

Since your at 3k and somewhat warmer temps I’d think just slightly leaner than the above would be perfect for ya. 

Sounds like the NE is helping ya, so stick with it for now. Next time you order parts pick up a NEDK and NEDL... Some larger mains too :)

Make sure you float height is correct (6.5mm) if you haven’t done so already. 

Also, helps to figure out which circuit is out of whack if you mark your throttle grip so it’s easier to tell how far throttle is open. 1/4, 1/2 & 3/4 can sometimes be hard to guess. 

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Yeah, float height is good, I re-check it every time I pull the carb just to be certain. So I guess the part I've been super confused about is won't 1/2-3/4 throttle range be affected at least somewhat by the main jet? Or is it more affected by the pilot? When I lowered my main to the 155 I noticed a big improvement, but I also lowered the pilot to the 45 that same trip (was using stock N3WK in 2nd the entire time). I have 38-42 pilots and 155-170 mains I can try whenever, just trying to understand as best as possible so I can keep carb work to a minimum, haha. Thanks again for all the help.

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