400ex wont go passed 1/2 Throttle, + Smoke under load?? Help please

[TL_2ENV]

Just picked up an 04 400ex for cheap, ran kind of choppy when i looked at it, i didnt test drive it.
anyway I took out the carb completely cleaned it out did all that, it idles great, i can give it full gas in neutral, no hesitation. However under a load when i gas it it seems that when i get to 1/2 throttle or more it just wont go stutters and it blows some smoke at the same time. It seems like just a main jet or something, but its super clean, and the bike is entirely stock. The smoke makes me think it could be something else.. valves or something/ I dont know too much about quads other then how to clean carbs, any help would be appreciated

[honda400ex2003]

what is the jetting at right now? should be 148 main, 28 pilot, and 3rd needle clip from the top (with the needle part down)
anything different than that would not work well lol.
steve

[TL_2ENV]

Says above^^
"Completely stock" Im basically at sea level or close to it. Draining oil now, pretty black and seems pretty full as well

I didnt check needle, i assume its never been taken apart before.. As for the pilot i put a 30 in it, (I do this to every 400ex i get, removes the requirement for a choke, or any cold starting issues) I buy n sell these..mainly so it looks good when it fires right up without a choke

[honda400ex2003]

Originally posted by TL_2ENV
Says above^^
"Completely stock" Im basically at sea level or close to it. Draining oil now, pretty black and seems pretty full as well

I didnt check needle, i assume its never been taken apart before.. As for the pilot i put a 30 in it, (I do this to every 400ex i get, removes the requirement for a choke, or any cold starting issues) I buy n sell these..mainly so it looks good when it fires right up without a choke

just cause it is stock doesnt mean nothing is changed. people do stupid things. you also put a 40 pilot in it not a 30 :D coil could be messed up a bit or a plug wire, main could still be clogged up a bit, it may not be getting enough gas up. lots of stuff it could be. Does it run any better with the choke on? I doubt it, but it worth a shot. steve

[honda400ex2003]

check for leaks too. esp around the head gasket and such. probably not it but could be. steve

[TL_2ENV]

Weird you mention spark plug, my boot is pretty badly ripped.. I just put fresh oil in, seems to do it alot less.. its really on and off..which maks me believe its the plug too, ill try to get a picture of the boot. Its pretty tore up. I also pressure washed the hell out of it yesterday, wondering if something maybe is still wet?? Either way it runs better then yesterday, it was doing it about everytime i got on it yesterday, today its maybe 1/5 times

[honda400ex2003]

i would replace it no matter what it is. get a multimeter and check for good continuity from the coil to the plug end and you will know if it is bad or not. if it doesnt have a good resistance it is bad. try a new dpr8z in it too and see how that works. is the filter cleaned good? it wasnt freshly cleaned right before it started doing it correct? it could be getting some oil through it and causing it to smoke and bog once it gets enough air through it. like i said it could be a number of things lol. steve

[TL_2ENV]

Here is a pic.. actually im not sure this would do anything the main contact is still all intact just not insulated, unless somehow its slipping off and not making a good condition because of that boot.
http://i17.photobucket.com/albums/b91/xz24cavalierx/spark.jpg

[honda400ex2003]

it could possibly jump spark over to the head from the uncovered area. unlikely but possible. steve

[TL_2ENV]

Thanks i forgot i have 2 other 400ex here, i guess i could try swapping the spark plug wire over, and plug

[honda400ex2003]

sounds good let us know. :D steve

[TL_2ENV]

Put a new plug, thought it was cured and it i was turning a corner and gassing it and it cut off again, its just like its starving for fuel or something. I really do not want to pull the carb back out i highly doubt the needle was changed. The only other thing i kind of notice is the rpms seems to fall slow, if i rev it, it seems a bit slower then what im normally use to , to fall back down. Im going to do rear brake pads for not and then maybe switch out a coilpack from another bike

When it does it the best i can describe is like a rev limiter..

[honda400ex2003]

i would try a new wire too not just a plug. maybe your main is clogged up. the needle wont have any effect there really so that wont matter. I just had my boat do it and it ended up being a bad plug wire. not saying that is your case but... does it still do it after you turn the choke on? if not then it is a gas issue. steve

[TL_2ENV]

Will try to ride it with choke on right now.. choke is going to block air so im assuming it wont even get up enough to get to the point where it does it anyway??

I went through the carb the day i get it, including taking out jets, sprayed with carb cleaner really well, and then compressed air..

[TL_2ENV]

ok doesnt run with choke on at all, as i didnt think it would. I can maybe give ie 1/10 throttle and it cuts out bad (from lack of air due to choke) Anyway have one more thing to add, it seems to do it alot if i shift at lower rpms, If i run it hard in first wind it out and then shift, and so on it doesnt really do it, however if im crusing in first, hit second and gun it it stutters for like 2-3 seconds and then picks up..like it has to catch up

I really didnt want to take the carb apart, that main jet has GOT to be clean, i went through it very well. But it sounds more like a carb issue does it not? Maybe the cleaner and air wasnt enough maybe i need a new jet or clean with a wire brush or something, i didnt bother to check the size but it has to be correct lol

[honda400ex2003]

Well at least you know it is not too lean lol. im not sure why it would do it more when it is running slower lol. It is getting tougher to diagnose now and i am not really sure what to do without being there to look at it. maybe someone else will be chime in. if it is all cleaned in the carb and all of the jets are correct then i would say that you have another issue with something else. did you try the coil yet? I would say that would be on the list along with the cdi box. since you have other 400s it will be easier to do some swapping to try different things. steve

[TL_2ENV]

Maybe its not a fuel issue what determines that? It could be running lean for all i know? i will do the spark plug wire thing soon, its all one piece along with the wire correct?

[honda400ex2003]

the end comes off of the wire but the majority is all one piece. I dont think it is a fuel issue either, that is why i am leaning toward a coil and other things that are not fuel related. do you have a multi meter? I would test some of the stuff first to see how it looks. I am in the process of buying one to have just for doing things like this. lol. steve

[TL_2ENV]

no i dont, i forgot i said it smoked, probably where the fuel thing started, but it doesnt look black, it looks like oil , white/blueish thats why i was wondering if it could be valves?

[honda400ex2003]

alright we can do some trouble shooting on the valve seals then too. does it some on initial startup and under hard accelerations? mainly on startup? you should get a compression tester and check that too to make sure it is good there. that will show if the rings are bad or not. it would smoke all the time if it was the rings. a leak down test would show if the valve seals are bad also. steve

[TL_2ENV]

Nothing on startup, idles great, i can gas it hard in neutral, no stutters or anything. Under a load it stutters, if i dont wind out a gear before shifting and then gas it hard right away

[hocman123]

maybe ur fuel filter is cloged if i rememer right we should have 2 one on the carb and one on the tank

[TL_2ENV]

ive never seen anything on the carb, when i cleaned the carb though i drained the gas tank, took out the petcock/filter thing and cleaned it as well.

[hocman123]

on the carb if u look in the pipe the fuel goes in there should be a srew that hold a second fuel filter and is hard to see if u don't know it is there

[TL_2ENV]

never heard/seen that in my life. That tube from the gas tank to the carb is completely hollow, you can and people do however add a fuel filter between those

[honda400ex2003]

it is in the gas intake of the carb, there are a couple of threads around that show hot to get it out of the carb. there is also one in the top of the petcock inside the tank. steve

[honda400ex2003]

http://www.exriders.com/vbb/showthread.php?s=&threadid=444274&highlight=filter+in+carb

this is the thread that has pics of the one in the carb. look at slightlybents posts. he has the pics of it. steve

[TL_2ENV]

Interesting, i learned something new, i def. blew carb cleaner in there but i never removed it, not sure if that would cause my problem or not but i guess i can try it. Im going on vacation for a week so ill piss with it after

[TL_2ENV]

just got back into town, think there is anything else i need to check while in that carb? Really dont want to do it again, would the fuel screw make a difference? Is there a guide use to set that? Ive never done one

[idk123]

take off the airbox lid

[TL_2ENV]

wish it were that easy, bike is completely stock, if it was meant to be without one it wouldnt of came with it. im going to go through the carb again tomorrow and hope for the best
I could not get that filter out of the carb today, that thing must be stuck in there pretty good

[TL_2ENV]

Well took it all apart again, thought for sure i found the problem, it appeared as if something was blocking the float thing, it didnt look like they were moving correctly, so i thought that was it, took it apart cleaned it out and blew it out, floats look good now but same damn problem. I can ease into high rpm, but if i push it hard it just stumbles..only under load. I can have it in neutral rev it all the way up and back down quickly without a problem

[beck125]

mine is the same damn problem i am with you on this one, it runs fine in high rpms just sitting but when i get on it and shift up it coughs and stutters and backfires, like when you try to run with the choke on. I am starting to think its the pilot in my carb, but im not sure, i am running 91 pump gas and i may try a lower octane to see i feel like mine is running rich, not sure

[idk123]

beck125 its not the pilot jet is for

idle to 1/8 throttle

[idk123]

just try to take the airbox lid off and see what happens

[honda400ex2003]

Originally posted by beck125
mine is the same damn problem i am with you on this one, it runs fine in high rpms just sitting but when i get on it and shift up it coughs and stutters and backfires, like when you try to run with the choke on. I am starting to think its the pilot in my carb, but im not sure, i am running 91 pump gas and i may try a lower octane to see i feel like mine is running rich, not sure

lower octane gas isnt going to do anything but make it ping and run worse. :eek2: steve:blah:

[TL_2ENV]

Originally posted by idk123
just try to take the airbox lid off and see what happens

Well ur my hero, either that or i got lucky right now lol. I just took it off and took it for a spin and seems to run perfect. What could be causing this since its completely stock? Ill try again in an hour or two see if i have same results

[hocman123]

maybe your a/f screw is agjusted poorly and causeung the problem

[TL_2ENV]

That was my next guess, must be that. Either way it runs fine now so im just going to leave it, im trying to sell it anyway!

[idk123]

im not sure my quad did that to i took the lid off to see the filter and i took it for a ride and i was all fine lol my quad is alll stock with a pipe and air filter

[MidnightBlade]

sounds like the main is too big and the a/f screw is wrong, turn the screw till it bottoms out and back it out 2 1/2 turns then experiment with it from there

[TL_2ENV]

Originally posted by MidnightBlade
sounds like the main is too big and the a/f screw is wrong, turn the screw till it bottoms out and back it out 2 1/2 turns then experiment with it from there

Bike is stock, so are jets

[MtnEX]

Rich and lean can sometimes be hard to distinguish between.

Is it still running good with the lid off?
If so, you might be able to blame that on your pilot work.
Changed the jet but didn't adjust the pilot screw.
Adjust it.

If it had you fooled on the lid thing, here are a few things to look at.

First, take off the left side panel. Start it up and watch what goes through the fuel line while it idles... if it has a clear fuel line you will see if there are any air bubbles, water, or if it leaks. Ride it and take a look at the line just before you know it is going to do it's thing.

Next, pull the top of the carb pull the guts out and have a look at the needle setting. Sometimes one will rev clean despite being lean on the needle... because of the shot from the accellerator pump. Sometimes one will run crappy because it is rich on the needle under steady throttle, but will still rev clean because the butterfly comes open so quick. Lots of possibilities.

Next, take the thing off, remove the float and inspect it. Put it in gas and make sure it floats. Sometimes they get messed up.

Last, pull the gas tank on off and do a compression test. If the compression is low, no telling how it will react... which just tricks you and keeps you chasing your tail at the carb.