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Jet alteration

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I have a '99wr400 and the pilot jet is this shorter version of what Kiehn jets you can pick up at any dealer these days. The newer ones have a little nipple on the end of them and are that much longer. Can I just saw the nipple :thumbsup: off and use the new style jets?

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no,you need the correct style pilot jet.

I'm at 3 1/2 turns for a #48. I have to special order these jets. You think I'll be safe just ordering a 50, or should I get a 50 and a 55?

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the slide plate is broken or installed upside down.no way it needs bigger than a 48.

Hey dude thanks. Could it have been a durty 48? I blew through it with carb cleaner quite a few times and could see daylight through it. I put a 50 in there and now I can get it to idle smooth... I should mention, when I got the bike all stock it had the 48 in it. I put a pro circuit t4 pipe on it and a wide open YZ airbox.

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very possible the 48 was plugged up.

Sorry to keep buggin you, but your the only one that steps up and answers jetting questions.

I soaked the #48 in simple green all night, then blew through it with carb cleaner. It looks almost the same size as the 50 when held up to the light. Put it in and it still doesn't want to idle even with the pilot screw at 3, 3-1/2 turns out. I put the 50 back in and it idles. It seems to want to die when I get it somewhere below 1 to 1-1/2 turn. I went riding this weekend. It was in the mid to high 70's, my elevation is 430 ft. With it set to 2 turns I always have to choke it to start it. (even when warm) Sometimes it takes around 3 or 4 kicks. Also if we stop to talk for a second it never fails i'm gonna stall. Not so much while idling but more so when putting around in low rpm's. Also my idle speed seems to be all over the place, sometimes it sounds high sometimes it sounds its so slow it stalls. I'm thinking of taking the air cut valve off to stabloize jetting issues. Having said all that it sounds like it's running lean right? I could try the 50 at a full 2-3/4 turns. But I can't imagine I need a #52.... Maybe I need to break the carb down completely and soak it and clean it, and put it back together??? Any suggestions are welcome!

BTW I will take a picture of the slide plate tonight and post it :^)

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do not soak the carb in anything.there is very delicate seals in the carb that well be ruined if you do.

you wont be able to see the difference between a 48 or 50 with your eye.

you have a slide plate issue.

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I took a few photos and videos of the slide plate in action.

Here goes:

http://www.throwhome.com/1.mov

http://www.throwhome.com/1.jpg

http://www.throwhome.com/2.mov

http://www.throwhome.com/2.jpg

http://www.throwhome.com/3.jpg

http://www.throwhome.com/3.mov

http://www.throwhome.com/4.mov

http://www.throwhome.com/5.mov

http://www.throwhome.com/6.mov

http://www.throwhome.com/7.mov

Accelerator pump seems to work :^)

BTW sorry if the vidoes take a few minutes to down load. I tried to keep them short. They are around 3 to 4 megs.

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Here's some more pictures.

100_3511.jpg

100_3512.jpg

100_3514.jpg

100_3515.jpg

100_3516.jpg

100_3517.jpg

100_3518.jpg

100_3519.jpg

100_3520.jpg

Starter jet

100_3521.jpg

Current pilot 50

100_3522.gif

previous pilot 48

100_3523.jpg

100_3525.jpg

Float level, held at just enough of an angle that it rests on needle valve

100_3526.jpg

100_3527.jpg

100_3529.jpg

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you need to spray brake cleaner (not carb cleaner) in the fuel screw hole.

it should come out the pilot jet hole,pilot air jet and the bleed hole in the carb throat.

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you need to spray brake cleaner (not carb cleaner) in the fuel screw hole.

it should come out the pilot jet hole,pilot air jet and the bleed hole in the carb throat.

Great! Ill try it out tonight. Also someone pointed out that I am missing a tiny little washer that goes between the spring, and the -oring on my pilot screw. I looked it up on the microfiche and there is an extra part there that I do not have. Anything to be concerened about? Been looking for an excuse to buy something aftermarket anyway.

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I got the Zip Ty fuel screw. So to test this out step by step I tried this first with the 48 pilot jet and the old fuel screw in there, after I cleaned out the fuel tube with brake cleaner. (Saw the cleaner shoot up through several places) The bike wouldn't even start. So I put the new fuel screw in with a #48 pilot screw, and I still couldn't get the bike to start... So I thought maybe this bike just needs to run a little richer than other bikes of the same model. So I went straight to a 52. Bike still wouldn't start. The spark plug looked like it might be fouled out. Replaced it, but still wouldn't start. I then remembered I had completely backed out the throttle knob earlier when I had the carb out. I opened up the idle knob a little and it started. I set the idle to a slightly high idle and the fuel screw to 2 turns. Then went and rode it around to warm it up. I kept it at a high idle. And tried turning the fuel screw in and out. It didn't really seem to make too much of a difference where I set it. Maybe I just don't know what to listen for. Also after having the bike nice and warm I still have to use the choke to start it. So I remembered that I really never gave the #48 a fair chance sense I had the idle turned all the way down. So, I put in the #48. I was able to start it. I drove it around and re-warmed it up. It was pretty touchy to the idle knob. If I didn't have it set just a tad high sounding, it wanted to die. I began trying to find the point of turning in the fuel screw that made it sound as if the bike was about to die (with intensions of then thurning it back in until it reached it's highest idle point), when in fact it did die. Then I got interrupted and had to quit for the evening. Can give it some more tries tommorow. But I'm beginning to get a little frustrated. Sorry for the long post.

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my brother has a WR400 and it backfire like crazy and the exhaustpipe turns bright red and gets real hot , he said it needs to be rejetted, so if i take into the dealers how much will it cost to get it rejetted

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my brother has a WR400 and it backfire like crazy and the exhaustpipe turns bright red and gets real hot , he said it needs to be rejetted, so if i take into the dealers how much will it cost to get it rejetted

It's almost always $40 an hour no matter what your having them do. There is usually a half hour minimum. On a 400 they almost have to take the carb out of the bike each time they try a different jet (time consuming). They may try and talk you into doing a dyno test if they have the machine. If they do those are usually $100. So with dyno test I'd say $140-200. Without a dyno test I'd say $75-$120... That's totally just a guess though. Call them and ask, they can usually give you a ball park idea of the cost over the phone.

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Manther - been following this on both the WR forum and here.

Did you ever get to try the ZipTy fuel screw, because if you're still dealing with your normal fuel screw minus the washer, you haven't eliminated that portion of the equation, you should eliminate the fuel screw washer issue and just go straight to the ZipTy permanently - the tips are identical, so it won't mess with your # of turns in/out at all, it's the same part just longer so you can reach it without tools. Besides, It'll make trying to get this thing running a LOT easier since turning the pilot screw (which you're doing a lot of right now) becomes a cynch!

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Manther - been following this on both the WR forum and here.

Did you ever get to try the ZipTy fuel screw, because if you're still dealing with your normal fuel screw minus the washer, you haven't eliminated that portion of the equation, you should eliminate the fuel screw washer issue and just go straight to the ZipTy permanently - the tips are identical, so it won't mess with your # of turns in/out at all, it's the same part just longer so you can reach it without tools. Besides, It'll make trying to get this thing running a LOT easier since turning the pilot screw (which you're doing a lot of right now) becomes a cynch!

Yes sir the last three attempts were with the new Zip Ty fuel screw in use (including it's washer). Matt thanks for keeping in touch on this problem. I hope to have to situated before this up and coming weekend. I'm not ready to say the new fuel screw hasn't fixed my problem. I may now just need to learn how to choose the right jet and set the screw.

Also on a different note. Someone mentioned that a lean main jet could be contributing to this problem. From what I have read about throttle position and carb circuits, I have a hard time believing that anything outside the pilot circuit could be involved here, but maybe my thinking is flawed. I should be able to try any new suggestions tonight. All suggestions are welcome. I guess my first step tonight should be to decide wether or not a #48 is too lean...

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Ok got the #48 to work now. With the idle knob set correctly and the new fuel screw, the #48 is in and is responding to changes in the fuel screw position. Sounds about the best at 2 turns out. And now I can start it warm without the choke. I'm going to do some plug tests to make sure the main circuit is not lean. (That is just for testing the main circuit right?).

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