400ex carb question [Archive]

ukweasel

11-18-2009, 10:31 AM

I recently bought a 2005 400ex that has been sitting in a garage for two years. I could get it running (sorta) but it would not idle, so i cleaned the carb. As I was cleaning i ran out of carb cleaner and was forced to use just wd 40 and very fine metal wire to clean the slow/pilot jet. When i reinstalled the carb it idled great and would do great at wot, but if you are just putting around or at an idle and hit the gas hard it will die. I wanted to see what yall thought before I took the carb off again....does this sound like a jet problem, meaning do i need to take the pilot out and let it soak, or should i try adjusting the fuel screw first (it has never been adjusted to my knowledge)?

next question, after doing some research on these forums I have decided my upgrades will be a lexx slip on (i'm on a budget lol) with a k&n filter and I will leave the airbox lid off. Does anyone have any suggestions on what pilot/main jet combo or needle setting would work best, or have a rough idea for where to start? I would like to keep from buying the whole kit if i can buy just a couple of individual jets. I saw the dyno jet instructions call this setup stage 2, which calls for a 170 main and needle position of 3 for my altitude (Huntsville, AL, app. 600ft). With these modifications would i even need to go up a size on the pilot jet? Does anyone know why the dyno jet kit comes with its own needle instead of using stock? Could it be because of the adapter? Thanks in advance for any advice.

ukweasel

11-18-2009, 10:34 AM

also thought I would share this site i stumbled across. i may have actually found it on the forums and forgot about it i don't remember. nonetheless, it appears to be a good resource for jets:

http://www.jetsrus.com/a_jet_kit_atv/honda_400_TRX400ex.htm

slightlybent47

11-18-2009, 11:21 AM

In my opinion the k&n filters are junk and let in to much dust and dirt for an atv.
Everyone I have talked to has had issues with k&n and I have seen for myself when a friend pulls off there k&n there is always some sins of dirt in the intake. Even if the k&n flows better it would be very minimal at best. I have done some test on my ex with the filter on and off and I can’t tell any deference at all between the two. I use the stock filter and use a foam sock over it with bell ray filter oil and I never see any sine’s of the filter failing to keep it clean. I have a full build on mine and I’m still running the stock filter.
In my opinion the k&n filters are a bunch of advertising hype and don’t help much if at all.

I would say no changes to the pilot jet with the mods you have. I did a 416 with a port job and cam and only changed the main jet to a 174 and it ran fine. And the plug looked good. I would soak it real good and blow it out good with a air hose.

honda400ex2003

11-18-2009, 11:29 AM

with a slip on and a filter at 600ft i would run about a 155 keihin, 38 pilot, 3rd clip position, and about 3 turns out on the f/a screw. I ran a 150 keihin (138 dj actually) with my t-4 and k and n with my box closed so you should be pretty close with that. 800 ft isnt going to make a huge difference in jetting like going from 600 ft to 3000 ft would. if you want to get a few jets from jets r us get 150-160 and you should be set until you do something a bit more radical like bore it. that should be around 4 or 5 jets. To each his own on the filter. I run a outerwear with mine and have had no problems in over 4 years of riding in just about any condition possible. On the machine running decent, if it has the stock jets in it and it has been sitting for that long make sure you put new gas in it and make sure the needle and everything is in the position and adjusted right. something may still be a bit loose inside there making it run funny. just an idea for you though. steve

slightlybent47

11-18-2009, 12:12 PM

All I can say is take the air filter off and ride it and see if you can tell any deference. I’ll bet if you'er honest you won’t be able to tell one way or the other. It’s a easy test and as long as you stay out of the dirt when you do it you will be ok.

honda400ex2003

11-18-2009, 12:51 PM

If there is no difference then the K&n must be pretty good, if there is no turbulence to slow down the air then it is doing its job, it is cleaning the air and not slowing it down at all. this is the best of both worlds. :eek2: the less the motor has to work to pump air the more potential for power that can be had. If the motor is not leaned out with the filter off it means that it is running the best that it can by getting enough air no matter if there is a filter or not. try with your uni or whatever you have, see if it pops and backfires on you with it off. Oh wait it does, :eek2: wow, i bet it is getting more air without it then it is with it. Come on dude relax with the filters. Every post anyone has had in the last week it seems like someone has been on here with get a uni, if it cleans the air what does it matter. you may have had problems with your k&n, i havent, until then, ill keep it cleaned, oiled with the proper oil from k&n, and let it run. fi i have problems then i will think about switching after exhausting the possibilities of not having it oiled properly and having it clamped down right and coming to the conclusion that it was indeed the filter that caused my problems. :rolleyes: steve

ukweasel

11-18-2009, 01:09 PM

thanks for the responses everyone, the reason i was going with k&n is because i have one on my car and already have the supplies to clean/recharge with so im sticking with that. i guess for the time being i should clean the pilot and recheck to make sure the a/f screw is at 2 1/4 out (isn't that factory setting?).

when i order filter and slip on i guess i will do as suggested and go with the 155 keihin and reset needle to 3rd position with a/f at 3 turns out for starters.

steve if this setting worked for you with a similar setup, do you know why the dynojet kit recommends the dj170 which is equivalent to the keihin 190? im looking at dj's instructions here:
http://www.dynojet.com/pdf/Q107.pdf
and the conversion guide here:
http://www.exriders.com/vbb/showthread.php?s=&threadid=344906&highlight=%2Ajet+conversion
does it have to do with that dj adapter and needle taper perhaps?

thanks again to all for input

slightlybent47

11-18-2009, 01:37 PM

That’s all well and good but like I said it seems to run the same ether way on or off. And no it dose not pop or do anything deferent ether way. I did the same experiment with both the 400 carb and the 450 carb I have now, and it ran exactly the same ether way on both carbs filter on and off. Try it for yourself and make you own decision.

The gains can’t be that much better to warrant the money. It’s like buying a stereo and one sees it has 000.5% distortion and the other sees it has 0000.4% distortion. Yes there is a deference but one that can only be seen on a graph but in the real world you cant here the deference with the human ear.

Same with the filter yes you can see it on a graph but you cant feel it in the way it preformes.

slightlybent47

11-18-2009, 02:12 PM

A k&n would be ok in a car cuz there is not that much dirt in the air. But for off road in these conditions I want the most protection I can get. But that’s me, do what you want.

honda400ex2003

11-18-2009, 02:12 PM

Originally posted by slightlybent47
That’s all well and good but like I said it seems to run the same ether way on or off. And no it dose not pop or do anything deferent ether way. I did the same experiment with both the 400 carb and the 450 carb I have now, and it ran exactly the same ether way on both carbs filter on and off. Try it for yourself and make you own decision.

:eek2: you dont get it and obviously never will. if there is no difference the motor can not get anymore air then is already going through no matter what. The air filter is not going to make a difference at that point. I agree with the air filter i have them in 3 cars, i have the stuff to clean it and it beats getting full of gas and oil to clean a foam one. The dyno jet one is for a built machine running that, the one you need is around a 142 stage 1, it will run terrrible with the 170 in it. the mostly stock motor with a good aftermarket slip on exhuast. the lid wont make that much of a difference. If you would like to put that in and see how it works great. I tuned it to what it ran best with. I dont run a 170 dj in my 416 nor does just about anyone else. the taper is just about the same and the length is the same on the needle. it fits into the jets a bit different. I ran a dj kit for a long time, actually until i did my 416 where i could not tune it properly with the 155 because it was too rich so i bought a 170 keihin and put the stock needle back in. it is a bit smaller than a 155 so it works perfect. hardly a 440 will need a 170 dj or a 190 keihin sometimes depending on the situation. Steve

slightlybent47

11-18-2009, 02:33 PM

Well Steve I guess will just have to disagree on the air filter thing. If you want to believe the marketing hype and it makes you feel better then go for it. I just thought I’d put my experiences on here so the man can have more than one opinion. You said that my carb would back fire if I ran without the filter and you are so wrong on that, it runs fine ether way. But it is really simple to test, ride with the filter on and run it with it off and if you are honest with yourself I’ll bet you can’t tell ether. To each his own.

Now on the main jet I honestly don’t know what brand jet the 400 carb had in it but I do know it was a 174 and the pilot was stock and it ran just fine.
That’s with a 416 12; 1 - S2 cam and head port with a wbmx4 slip on.

honda400ex2003

11-18-2009, 02:37 PM

i did not say your carb would back fire your motor may if it is running too lean. no more on the filters either one will work take care of them, maintain them correctly, get an outerwear if you ride in a ton of sand for both if you like. they can be found on dennis kirks site. the main in a stock 400ex is a 148 keihin jet, the pilot is a 38, the needle is on the 3rd notch if it has them, the newer 05 + ones do not you have to use washers to tune it, the f/a screw is 2.25 turns out stock for future reference purposes. steve

slightlybent47

11-18-2009, 02:44 PM

That’s cool everyone’s entitled to there own opinion. I'm done with that. Agreed Let’s move on.

TRXRacer1

11-18-2009, 04:24 PM

The only people that have dirt slip past a K&N are the people that don't know how to maintain them......... period!

slightlybent47

11-18-2009, 05:30 PM

Man I got to disagree on that. My friends used one for a while and stopped because he had dirt come through his. And trust me no one keeps there bike and all the parts to it as spotless as he dose all the time. To the point of being anal about it. And I have seen the way it was mounted and it looked solid. But like I said to each his own. If you like it then that’s cool to no big deal. But don’t try and tell me it wasn’t well maintained.

kennyo1

11-18-2009, 07:16 PM

I have a 2005 also( It also has a K&N) I have has similar problems after cleaning the carb. Idled fine, put around fine but open the throttle and it falls on its face. The problem is that the carb sometimes slips out of the boot. When you open the throttle it sucks too much air and kills the motor. Hope this helps. CHECK THOSE CARB BOOTS. :)

honda400ex2003

11-18-2009, 07:51 PM

Originally posted by TRXRacer1
The only people that have dirt slip past a K&N are the people that don't know how to maintain them......... period!

amen, i assume you have read the whole thing. it may be a losing battle but maybe if we just keep telling it how it should be maybe it will sink in. Almost like,
All I can say is take the air filter off and ride it and see if you can tell any deference. I’ll bet if you'er honest you won’t be able to tell one way or the other. It’s a easy test and as long as you stay out of the dirt when you do it you will be ok. funny stuff. right there is how the dirt got in. :p :p lol. sorry, i am not going there again. steve

slightlybent47

11-18-2009, 08:06 PM

Hold a k&n filter up to the light and you can see right through it. It’s full of holes, dust and dirt go down to 000.5 microns and if you can see through a filter then dirt can surely get through.
And if a filter is so fragile that it can tear and let in dirt what good is it.
I won’t risk trashing a good motor because I used a filter that can let in dirt.
And for what 1/8 of one hp, it isn’t worth it.
Sorry but you won’t convince me otherwise.

ukweasel

11-18-2009, 08:43 PM

So I'm soaking the jets right now in cleaner bout to put them back in after I've gone over them once more for good measure. Does the 05 require a special tool to adjust the a\f screw, cuz what I'm looking at looks like a round lil tit that sticks up with a flat side on it. If it does require a tool then I know its never been adjusted cuz I know the original owner. Any input? Thanks

honda400ex2003

11-18-2009, 09:09 PM

i believe it requires a certain d shape tool to do it but you can make your own out of a certain type of bullet shell. I would do some searching for the 2005 carb adjustment tool on here, i know someone has made one to do this. you may be able to get something makeshift to do it too though. steve

TRXRacer1

11-19-2009, 06:41 AM

Originally posted by honda400ex2003
amen, i assume you have read the whole thing. it may be a losing battle but maybe if we just keep telling it how it should be maybe it will sink in. Almost like, funny stuff. right there is how the dirt got in. :p :p lol. sorry, i am not going there again. steve Steve that's so far out there I think we've said enough. You won't win a debate when logic has been replaced with comical reasoning. Sorry bent, but you've got one skewed view on this topic.

ukweasel

11-19-2009, 07:24 AM

i put everything back together and just put the carb back on. I left the airbox boot off and throttle off and just opened it with my finger. No difference from before, still falls on its face from an idle if you pound the throttle, there is even a little bit of popping and slight backfiring until it gets completely warmed up. The gas in the tank is fresh and i've only ridden it with the current spark plug once. I guess I will have to buy the "D" tool and see if any adjustment there will help. I should prolly explain in detail what I did when I cleaned the carb originally in case I overlooked something important:

The thing sat for about a year maybe two. I pulled the carb and cleaned the bowl, removed the jets and cleaned them, cleaned where the jets are seated, removed the float and cleaned it and its seat (it moves very freely). I did not completely disassemble the entire carb and soak it as I have done to some carbs in the past. I didn't buy a rebuild kit, I reused the original gaskets when i reassembled it. Assuming the a/f screw has never been adjusted (which i think is a safe assumption) is there anything I have overlooked that I should check until the "D" tool gets here? Thanks guys

slightlybent47

11-19-2009, 10:08 AM

Originally posted by TRXRacer1
Steve that's so far out there I think we've said enough. You won't win a debate when logic has been replaced with comical reasoning. Sorry bent, but you've got one skewed view on this topic.

What is the purpose of an air filter?
An air filter is designed to trap dirt and dust from entering the engine and causing damage. If two filters are the same size and one flows better that the other then it would stand to reason that the holes in the one are bigger than the other. How do I know the holes are bigger? “I can see them” And if the holes are bigger, then it would also stand to reason that it will let in larger dust and dirt particles. And it would stand to reason that the larger particles will do more damage and could be more of them getting in.
And like I said in my earlier statement yes the k&n may show some small gains in air flow but at what price? “Your engine” k&n doesn’t say it filters better, they claim I flow’s better. Why do they do this? To sell you there filter.
Why do you think all manufactures put the foam filters on there new bikes instead of the so called better flowing filters? Because they are better at protecting the motor and that is why the filter is there in the first place.

Sorry I don’t know about those magical wind vortices and such nonsense.
They have been using that gimmick on cars for years by selling you some magical device that changes the air flow and make more power. If that were true don’t you think the engine manufactures would pick up on that and put it on there motors to make more power? It’s all marketing.

Call me crazy but for what small gains you may get from the k&n filter is not worth risking my motor. I’ll take a small loss in power to keep my expensive motor in one piece. I don’t see how that’s so hard to understand.

Sorry ukweasel - I don't meen to step on your threed.

grovesbm

11-19-2009, 08:02 PM

drain gas tank, swish new gas around in there couple times pour it out, get some 93 octaine and let her rip i had the same problem and prolly never even neded to take carb off

f4iracer

11-21-2009, 10:18 AM

ukweasel, your thread has been jacked by a filter argument!

How is the quad running now? I'm interested to know because i also have the same model quad.

ukweasel

12-06-2009, 04:18 PM

Thought I'd give an update, all my parts came in and I installed the pipe, filter, and jet kit. I put the needle on the third position, a/f screw at 3 1/2 turns out, and used the dj142 main. I couldn't ride it so I was limited to just testing it as it was sitting. I was pleased with the sound. I just ordered a 40 pilot becuase I have a slight stumble if i hit the throttle hard from an idle. I was pleased with the tone, but will probably remove the quiet core becuase I like loud pipes. The only thing that was odd about the pipe install was that the mid pipe doesnt fully connect to the header pipe. I will attach pictures of it. Has anyone else encountered the same issue with the LEXX? does anyone know where I can order a new idle screw (mine broke) or an old-style a/f screw that will work with a flat head screw driver instead of that odd D tool?

honda400ex2003

12-06-2009, 05:34 PM

sounds like you got it pretty close. the only thing i dont care for is taking out the arrester. not only will it change your powerband it will also make it louder:( . otherwise, i think you may be a bit rich if you have a stumble but i guess it is hard to tell. you may want to try the second clip position and see how it goes instead. just an option and opinion for you. steve

ukweasel

12-06-2009, 08:28 PM

Thanks for the input, i was thinking i was too lean on the pilot jet becuase if I run it with half choke it doesn't stumble when I stab the throttle from an idle. I have no idea if I'm close on the main yet with the 142 becuase I wasn't able to run it outside the garage. I will hopefully dial it in this coming weekend though. Is my reasoning sound on the pilot jet issue? I'll add another pic of the whole lexx system installed in case anyone cares to see it.