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Thread: how to adjust the needle on an '01 400ex

  1. #1
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    how to adjust the needle on an '01 400ex

    I need to know how to go about adjusting the needle on my carb. I know how to change all the jets and I am familiar with the setup but I am not quite sure which screws to pull to get that needle out and how to adjust it. Any help would be appreciated guys.

  2. #2
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    the two that have the mounting point in the top brass cover have to come out of the sleeve to get at the needle. it is not bad just dont strip them out and you should be good. I would suggest just taking the screw out of the arm that goes down inside the slide so you can get into it a bit easier too. good luck, steve
    2019 Maverick X3 XDS Turbo R
    2003 TRX 400EX
    2016 HONDA RANCHER

  3. #3
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    up leans it out and down richens it up too. that is with the clip position on the needle. if it is stock it should be in the 3rd position from the top. steve
    2019 Maverick X3 XDS Turbo R
    2003 TRX 400EX
    2016 HONDA RANCHER

  4. #4
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    I have an outerwear airbox lid, a pro design intake kit, choke removed, and spark arrestor taken out of my stock exhaust. my jetting is 42 pilot and 155 main, and about 2 and 1/2 turns out on the fuel screw. I am running at 5000 feet. I am a student so I don't have a whole lot extra to spend on mods so I just did some cheap stuff. what do you think about the jetting and should I leave that needle on the third?

  5. #5
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    you should be alright on the 3rd spot if it runs good. some good cheaper mods are a sparks key, a 450r carb, and a hotcam stage 1. I would say that the 42 is a bit rich but if it starts and idles good why mess with it. the main sounds to be pretty good with what you have. how does the plug look after a chop? steve
    2019 Maverick X3 XDS Turbo R
    2003 TRX 400EX
    2016 HONDA RANCHER

  6. #6
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    I haven't done a chop. Isn't that where you run it where you wanna test it and kill it and check the plug? Ya I thought a 42 was a little rich too but it's got balls off the line so I think it's ok. I have a sparks key on the way right now. Does it help quite a bit? I also backed the screw out a half turn but my friends ex is exactly the same as mine except I have a better intake and his pulls harder through the mid range up the hills. I am not sure if his needle is adjusted or not because he bought it used and hasn't checked. That's the only thing i think it might be. His jetting is the same too. Unless he has a sparks key and doesn't know it. Mine should just be faster and it's not. Slightly annoying. Could it have to do with taking the arrestor out and not having any back pressure? his is the same though so i dont know. Any suggestions? Oh and when installing the sparks key do I have to buy a massive allen wrench to get that big screw out of the middle so I can take the case off? I know I need a gasket and I ordered one.

  7. #7
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    i am not real sure on the key, since i have not put one in. That is how you do a plug chop just make sure you put in a new plug after it is warmed up and then test where you want. you can go to the 2nd slot on the needle to see if leaning it out a bit helps but taking the baffle out of the stock stuff is not real good since it does not have as much pressure but if it jetted good you should be alright. To get the plug out you should get a big allen socket it makes it much easier and is not as easy to strip or mess up. i have a whole set that is for a 3/8 socket set so that is what i use. Steve
    2019 Maverick X3 XDS Turbo R
    2003 TRX 400EX
    2016 HONDA RANCHER

  8. #8
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    First I wanna tell you thanks for all your replys to my questions. I really appreciate your help. Anyways, Today I was riding the dunes, and I switched from my 13t front sprocket to a 14 just because I like my second gear to be a little longer and towards the end of my ride my quad started acting like the choke was on! It was sputtering and crap just all of a sudden. Right through the mid range too. It wasn't in the pilot circuit, I think it is the needle. Like you said I think it needs lowered a notch to lean it out. But what was weird is I rode all day the other day with the jets the same as they are now and no sputtering. Sprocket maybe? I doubt that would do anything though. Kinda weird. I am going to lean out the needle a notch and see what happens. If that's where you think the problem is?

  9. #9
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    and by the way my choke is removed, so no possibility that it was on

  10. #10
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    I think it needs lowered a notch to lean it out.

    u may of made a typo but if u want 2 lean the needle out u want to raise the e-clip on the needle! For example if ur on the 3rd notch down from the top u would go to the 2nd notch from the top 2 lean her out. just wanted to make sure that u do it right cuz i personally dont like messin with those 2 shi*** screws that u have to take out 2 get 2 the needle-they strip very easy so take ur time!!
    2008 TRX 700XX- brand new and bone stock!!

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