Honda 400EX ATV Carb Rebuild & Cleaning | Partzilla.com
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- เผยแพร่เมื่อ 7 ก.พ. 2025
- Buy individual Honda TRX400 carburetor parts for your rebuild: bit.ly/TRX-carb...
Buy a TRX400 carburetor rebuild kit: www.partzilla....
Is your ATV hard to start or does it idle rough? This is the place. In this video from Partzilla.com, John will show you how to disassemble, inspect, and rebuild the carburetor on a Honda TRX400 EX. Above you’ll see two links. One offers a list of the individual parts you may need to address specific issues with your carburetor, and you’ll also see a link to a carburetor rebuild kit, which has many of the parts you’ll need.
Get a closer look with our Honda ATV parts diagrams. You can see all of the parts for your carburetor here: www.partzilla....
Read how to do this job step by step: www.partzilla....
Starting issues aren’t confined to the fuel system. Diagnose starting issues with your electrical system here: • Help! My ATV Won’t Sta...
Change the oil and clean the air filter while you’re taking care of maintenance: • How To: Honda ATV Oil ...
VIDEO HIGHLIGHTS
Carb disassembly - 4:06
Hose inspection - 4:44
Pre-filter inspection - 5:14
Pump diaphragm inspection - 5:36
Float bowl and float needle inspection - 6:08
Air/fuel adjustment needle inspection - 7:38
Main needle and idle jet inspection - 8:48
Cleaning the carb body - 10:34
Cleaning carburetor passages - 11:29
Carburetor rebuild - 13:16
Carburetor installation - 19:01
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In the video we’re working with a 2007 Honda TRX400 EX, but you may have similar steps for your Honda ATV. If you’re not sure whether these steps apply to your machine, leave a comment and we’ll get back to you.
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• How to Test ATV Stator...
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• ATV Chain Replacement ...
I don't even speak much English and just watching carefully do it helped me save more than 500 dollars. My family and I can't thank you guys enough! Muchas gracias!
your videos are the reason my quad runs accordingly lol.
I followed this video for partially rebuilding my 2006 TRX400EX carburator with the AllBalls rebuild kit. I honestly know next to nothing about carburetors, but this video helped. The video you have on the valve adjustment was key too. Quad runs perfectly now.
I hated that rebuild kit couple parts arent the right size compared to the oem the main was too small
I have never done anything like this before and your video made me 100% successful! Thank you.
Great to hear!
Watching your videos gives me the confidence to do it my self. I'm already a hvac mechanic but this is a different beast .
ruben flores just got into the HVAC trade. I am currently a new home installer
What cleaning solution do you use in your ultra sonic cleaner to clean carbs?
Great video, got my quad running thanks to a few of his videos.
Thanks your video helped me get my 2007 trx400ex going...
+Garth Morris: Glad to hear it, Garth! Happy to help.
These are the best videos to ever be made
Thanks! We think there should be some TH-cam Oscars or something.
A way to make an adjustment tool for the air-fuel needle on the bottom if the carb is on the bike or off.
Take a piece of hot glue melting it on the end jamb it up there letting it cool then trim off the excess on the sides.
Cut the hot glue to the length you need to get it in there. Put a mark right in front of you on the glue stick. Good to go:)
1/4 nylon tubing will work as well just get the tip of it rounded when hot before you push it up there.
Great video, this really helped me in cleaning my carb up and also finding my problem. My carb was missing the screw to the slider arm. It still ran but would not rev out and I couldn't figure out why. It has a ton more power now. Thanks for the great video.
Will rebuilding my carburetor stop my overflow tube from leaking when i have my quad turned on during idle?
I have a 2007 honda trx 400ex just gave the carb a good cleaning but cant figure out where the vacuum hose connects to. part number (95005-45001-50M ) It has a plastic Y piece close to the carb but got no clue where it goes on the other end. My stock petcock is not vacuum operated so where does it lead on the other end? It wasnt capped off. Cant remember taking it off when disassembling cant remember where it connected too...
You are a great mechanic I would rather watch these then tv luckily I don’t have any of these problems
This video worked on my 2000 Honda 400ex. Thanks!!
Why don't you have the "anti-cavitation device" in the float bowl? (the plastic piece around the main jet that helps keep the fuel from foaming at high rpm which will cause the carb to be lean)
Atv sounds as if it’s sucking air can that be possible a leak on the small hoses on the carb , it runs during the choke and without this video I was going to spend big money so thanks for the help , just one part of the float bowl wasn’t shown which was the plastic thing on the jet that’s very removable...
Great video...might need to rebuild mine soon...the 400ex doesn't idle very well...
You should make a video on a 300ex. How to rebuild the bottom end.
At 13:50 you say the "spring follows" by the washer and o-ring. At 8:11 you take the needle out saying "there is your 0-ring and there is your spring" falling out last and you never mention the washer with that assembly. This just so happens to be the only reason I came to this site to find out the order as the sob fell out when I wasnt looking.
You put it back together wrong it looks like because the washer would have to prevent the spring from damaging the o-ring after the spring sealing it all in the carb.
Unless the washer and o-ring jumped over the spring while you carefully pulled that needle out.
Then again you had the needle out halfway when you said that and it looked like the o-ring was on the needle. ty
Had a crack in one of my vacuum lines
Would that make the bike run horrible? Didn’t have any debris in carb and all jets were clean. Thoughts?
I just bought a 07 400ex and oil change and spark plug i can take the carb out no big deal but put it in back in place man those really tiny things
The hoses that connect to that plastic "Y" port, what is the purpose of that line?
When I put my throttle cable back on the carb the idle speed went up. I can't figure out if I did something wrong or how to fix it.
There’s a hose on my 04 that I don’t know where it goes. It just hangs, when I shut off the quad it leaks gas. I plugged it off and now it wants to stall at idle. I looked everywhere for a place for it taking the length of the hose and searched all over for a location. Worked on cars all my life this has me baffled. Any thoughts???
Why didn't you check the holes on the sides of the Jets? Just because it sprays through the bottom of the jet doesn't mean it's getting vacuums through the side holes. Where do you get the mixture screw socket
Right by my choke, there is a spout that is spitting gas out when get on the throttle while I’m driving. There should be a line there but I don’t know where it goes
Will the rebuild kit become available again?
do u guys sell the air fuel flow d shaped key
Great video, you fill me full of confidence to perform repairs.
That's what we love to hear. Thanks for watching, Walter!
So many Thanks to you for these videos, I'm never to worried while buying n trading my atvs! Awesome Awesome explanations tips n great views n perfect part info just hit pause! Ty Ty
where does the Bulk Hose Vacuum Hose #45 connect to on the opposite end of the "Y"
Thanks for the videos you post , it really helps keep up the good work !
I think its hilarious at the end, it barely turns over, and he says There u go lol a no sir let it idle and we'll see
I felt cheated there at the end too. All that for some bs little bump.
Thanks for making the vid, very helpfull, and most detailed that I have seen so far. Got my carb off and about to start breaking it down.
+easttxtycoon: Awesome! Thanks for watching Easttxt. Shoot us a comment if you have any issues breaking down the carb and we'll do our best to help. We also have an OEM diagram page detailing how everything goes together on the 400EX carb: www.partzilla.com/parts/search/Honda/ATV/2007/TRX400EX+A/CARBURETOR/parts.html
Hello, on my trx400ex - yesterday I took my carb out for easy access to my starter which I rebuilt. After putting the carb back in along with the airbox - i turned the gas on, I immediately noticed that I am getting fuel in my airbox. This was not an issue prior to my taking the carb out. Can you tell me what the likely cause of this is? Thanks...you make great videos and raise my confidence level when working on my 2000 trx400ex
First things first, check your hose routing. You may have crossed something up
for the main jet the part that has the nut on it am i supposed to tighten it all the way down then tighten the nut
Where do the 2 hoses go from the carburetor? The one that T’s at the top and then there’s one on the bottom???
Im having the same problem lol did you figure it out?
I found the little black shock absorber looking gasket (.25" long about 1/8" diameter)/ bushing it's pictured in some of the rebuild kits, but you don't mention it, where does it go?
do you need the baffle plate? I took my carb apart apart and it didn't have the d hexed shaped bolt for the air screw it was a flat head screw with a gasket
Next video take out two bottom subframe bolts and push up! Giving you clear view of all of it!
I have the same bike you worked on I cleaned the carb completely used air and carb cleaner to blow out all passages all jets are clean and free of any debris drained all fuel from tank replaced with fresh fuel fires up fine with throttle revs fine but won't idle... Any suggestions?? Thanks
What do you use in you’re ultrasonic cleaner ?
the nipple on the right side of the carb,facing the back end is that a overflow hose? I have fuel leaking from there so im assuming i need to clean the car but need t know f im supposed to have a hose there & if so where does it route?
2002 Honda 400EX. Backfires through carb will not idle stalls out. Runs fine up top pretty strong. Set for a while the person told me I purchased it from. Did a carb rebuild kit and still same issue. Help please!
I was blowing air through the pilot jet hole and a little rubber plug popped out. Can you tell me where it goes?
Hello I have Keikhin carburetor modeled KTB and it has two black adjustment handles can you please tell me what those are for and how they work together briefly you’re awesome thank you.
Good breakdown. But I want to hear it run, at least Idol for 10 second But I saved the video in case I have to work on mine someday.
do you have the hoses for sale as a package. I see I can buy all the individual pieces like clamps and hoses, but just wondering if I can buy all the hoses in one package. I do not need the fuel hose that goes to the petcock or the hose that goes from inside the throttle cover. just the two ports on the side of the carb and the other one by the bottom of the carb that is like an overflow or something
I'm just curious why would people show people cleaning the carb or replacing Jets and needles why on the 400 EX don't you guys ever speak of number 38 in the schematic JET, SLOW AIR (#110) you speak of the pilot jet the main jet the needle and it's clip positions but my 400 don't even have an adjustable needle. I just bought a jet kit and I realized after I bought it by looking in the schematic it doesn't show that number 38 I don't even see it being sold inject kits what is that for?
great video my carburetor leaks gas constantly from a small tube on the bottom facing to the rear what can that be even when its running
Most likely a stuck float or worst case a rebuild.
I don’t know if your still answer these but i’m hoping so. i just got a new carb for my 2002 400EX and it’s idle is very high . I know where the idle screw is, I just don’t know what to do
Turn it counterclockwise 1/4 turn at a time until your idle resolves.
So what happens if you don't have a screen filter for the incoming fuel?
Mine doesn’t , should be fine
Got a keihin carb can I take the jets out my old carb and use them in the new on I have moose racing cdi box airbox delete with k&n filter dmc alien slip on will I have to do additional tuning
What jets do you recommend for an open air box and a K&N air filter with a slip on white bros pipe?
Hey there, I cleaned out the ladies 400ex and while twisting down the throttle cable bolt to the carb i knowticed the mental tubing doesnt sit straight or to the right... it sits facing left when skrewed all the way down which interferes with the placement of the gas tank. Any ideas on what to do? Probably a no brainer but im having issues lol
Hello, I have a 2000 400ex. I rebuilt my carb tonight following your direction in this video. Thanks for the info. Question, when I got to the part where you use the d-shaped tool to remove the air/fuel mixture (at the 8 minute mark). On my carb it was not d-shaped and the head of it was practically flush with the top of what was screwed into. In other words, there was no where for me to turn it in (2.5 turns in your example) before backing it out. As a result, i don’t know how to set my air/fuel mixture precisely. Please sdvise. Thanks for your help.
The D Shape came in later years. Typically, you can put it at 2.5 to 3 turns out to start and adjust later if necessary.
Great video! Started tearing down my carb for cleaning and rebuild, realized the throttle stop cable was broken off the thumb screw. I ordered a replacement from you guys, is there a video from Partzilla that explains how to remove and replace the throttle stop assembly on a 400EX?
+Rob B Not yet. We had moved on from the 400EX but are going back to it to cover a couple more topics. I'll throw this one back into the list.
i didnt do a as though rough cleaning as this just the jets and bowl. I put it back together now it will not start at all just turning over once in a while get a small putt. There is spark and fuel going in what could it be??
Thanks for the great videos! It helped me with the carb rebuild. I have a question: I rebuilt the carb on a Honda trx 400ex 2006. When I started the atv, it was started and ran for a a minute or so. It started a couple times right there and then. However, after those few starts, now it doesn't start. The engine turns over but that's it. It's got a new battery as well just so you know. Could it be the carburator? Any ideas will be much appreciated. Thank you.
Hard to say...could be a pinched line, incorrectly connected or the air/fuel screw, needle valve...you could have missed some debris when putting it back together and clogged up the works. Best to just go back through it and see what you find.
if my quad dosn't rev all the way and bogs when i throttle it all the way down does that mea that i have to clean the carburetor
Hello what solution do you use inside of the ultrasonic cleaner thank you?
my 300ex jetted and stage 2 hot cam wants to idle fine at first for a few minutes then it starts idling way to high any ideas?
I got a 2003 honda 400ex. It got a k&n air filter and k&n air box power lid with a big gun slip on exhaust. It spits back into the airbox when cold and floods on idle sometimes. when I rev it theres abit of black smoke witch would indicate flooding. What would be the recommended jetting for under 5000ft?
All the aftermarket additions change the jetting. There is no sure fire solution. Units react different per mod.
When I took mine apart there was another plastic holding the float. I put mine back together now it leaks all crazy. The rebuild kit I got has a seal that seems stretched, doesn't fit in the float bowl groove, is that normal? Carb leaks all crazy now.
Hi I was wondering about the mainjet I removed and cleaned it. But the little lock nut moved up or down. Does that matter and how should I seat the main jet now that nut has moved?
all you have to do is snug it back down. just tighten each nut on the main jet and it will be just fine!
What solvent do you use in the ultrasonic cleaner
Please do a build series on 2004 trx450r
Partzilla I’m lookin for a video for an 05 yfz450 carburetor rebuild. Thanks
I did this pretty much the same but I didn't mess with the air mixture screw. I got it all back together and now the bike is idling really high. As soon as I turn it on it seems like the throttle is pushed down. What could cause this?
Nevermind brain fart. I didn't twist the carb all the way onto the throttle cable when re installing it. Hope this might helps someone else
I know it's just a 250 compared to one of these 400 but can u please make a video on how to remove the stator of a trx 250ex? I cant seem to find a video on how to remove the stator.
The stator is on the front of the engine on that one, if I remember correctly, it's a little weird. I'll try to get a unit to do a video on.
Great video just wondering if this would be the same curb cleaning process for a 2004 Honda TRX 450r sportrax quad?
Regards
Process is the same, but the carb is slightly different, if I remember correctly.
Very good videos you make, thanks a lot.Does it take many hours to rebuild a carburetor like this?One working day?
One day
do you have a video showing how to replace a choke cable on a 2006 trx Honda rancher 400fa ?
We haven't done any Rancher videos yet, but choke cable is a good idea. We'll add it to the list of repair video ideas. Thanks for the feedback, James!
what is fuel is leaking out the overflow and wont stop? that the floater?
Yes
I just noticed gas is leaking during idle out of the drain port hose, i secured the bleed screw. It seems as if to much gas is in my float bowl, would this have to do with my needle jet or float valve any suggestions?
+Drago23 After removing float bowl I did find float valve dirty, cleaned and reassembled it, no more leaks!
So what about the jet set holder that goes under the main? Never seen it, but it's in diagram for it and I can't figure out how it goes in. 😤😤
The plastic piece? It just sits over the jet mount.
Great video! Question, before I remove the carb my honda sat for about 3 years any suggestions on how to clean the fuel tank? I removed the petcock assy/screen kit which will be replaced because it was disintegrated with that honey like tar build up you mentioned . When I removed the fuel line from the fuel tank I didn't see a screen prefilter and also found that same build up. I will most likely purchase the carb kit but any suggestions on how to assure my issue does not lie outside the carb?
+Drago23 Best way that I know is a bit old school, last time I looked in the mirror I think I' qualified. Spray a whole can of carb cleaner in the tank, add in a few nuts and bolts, shake it for a few minutes, then let it sit over night. That should break down the glue in there!
+Partzilla.com
Thanks for the advise, extremely helpful!
+Partzilla.comI Finally broke my carb down and thanks to your step by step procedure my 2005 ex is back up and running perfectly. That trick of the trade worked like a charm. Keep up the good work I will surely check back for upcoming videos.
There is a small hose that is connected to the carb below the choke...I rode yesterday and when I woke up today there was gas leaking out of that hose...and I can't find where it was connected to. Any help?
kyle bienia over spill drain maybe
those clips that hold the air box to the frame, were they used on earlier 400ex 's as well? I have a 2000 and I am not seeing on my air box the same clips
Might be slightly different on a 2000.
Nice... part of my pump diaphragm pieces went flying.
Where the D tool goes for the air fuel ratio, i dont have a D shape, its indented in a bowl shape what should i do?
Where can a person purchase that D style adjuster tool if you don’t mind me asking ?
Is this the same carburetor for the 300ex? I'm having trouble finding the rebuild kit for it.
thank you sir, it works perfectly for me on a TRX400EX 2012. It's an amazing tutorial!
Thank YOU for watching!
Does a Dynojet kit have all the things needed to also rebuild the carb? Like the rebuild kit that they sell?
It should come with a variety of jets and parts, but I don't think it comes with gaskets. It would depend on what you need for your carb or how much you're rebuilding. If you don't have leaks and it has just sat for a long time, you should be good.
Partzilla Thanks for the response. The problem I'm having is my 400ex won't idle when cold. I read that it should be jetted to a 42 pilot jet.
Using that kit should put you on the right track. Sounds like the jet is clogged.
I just purchased a 2005 400EX that had been sitting in a garage for a couple of years. The quad runs strong but it won't idle. It will turn off within a second or two if throttle is let go. It has fresh gas. What can I do to make sure it idles properly? Thanks.
Clean the carb! Anytime it sits for awhile, the jets are probably clogged.
We’re is the carb drain for a 2005 trx 400ex
Hey John the plastic part under the main jet when you pull off the bowl diagram 25 on your website what is it for...mines was sitting on the bottom of the bowl when I pull it off to rebuild it with a new kit....I didn't put it back in....will that cause fuel to overflow out of the overflow tube.
#25 on the diagram is the float gasket. Is that what you're talking about?
www.partzilla.com/catalog/honda/atv/2007/trx400ex-a-trx400ex/carburetor
Partzilla #27 i meant...sorry
For the air fuel mixture. If I buy a new carb will I next to set it or will it already be set?
OEM carbs come set to stock settings. You may need to adjust regardless.
Partzilla ok I have one more question. I have it running now but after a minute or so while running it the pipes start to get red hot. Any suggestions?? Thanks in advance
Bread Winner Running too lean. Might need to adjust more or rejet.
Im looking to buy the seat for the float needle that you've got in the video. The problem is it doesn't show up on any parts diagrams. If anyone knows where i could find one it would be very appreciated.
Put a new carburetor on my 2005 Honda rancher 400 and it won't start. What should I do?
Quick question, I have 99 Honda TRX400EX, There is a small outlet or port at the bottom of the carb toward the back of the quad that was pouring gas out of it the other day and I'm trying to get the correct answer as to where the hose that was connected to that port/outlet goes to? I'm being told it connects to nothing and that its just and overflow. Also, on the side of the carb, there is two short hoses that connect to a Y or T and goes to one long hose, it was also hanging down. Can you tell me where that connects to exactly? Thanks
If there is a hose, it doesn't connect anywhere. It is basically an overflow to vent fuel. If it's pouring fuel out consistently, your float could be sticking or it's time to tear down the carb. The 2 into 1 hose is the vent hose. It goes in the hole in the splash guard behind the fuel tank.
Ok, Thank you for the information. It was a brand new carb, only had a few hours on it. I have ordered another one to install in its place. Thanks again!
so I tried so many things to fix mine at first it was leaking second I had to push the gas so it would turn on third I bought a new carburetor from amazon and it started to rive hella nasty last thing I cleaned the old carburetor and it didn't work
What about the little “hat” thing that sits over the main jet is it nessassary?
Yes
You arerallyclear in what you do. Can you do one about a Yamaha raptor 660 2002
Added to the list!
how do you remove the fuel hose so easily? someone help!
is there something called a baffle plate inside the carb because I looked in the manual and it says there is something called a baffle plate and mine doesn't have it
Not sure what that is referring to. Here is a diagram and parts list for the carb. www.partzilla.com/parts/search/Honda/ATV/2007/TRX400EX+A/CARBURETOR/parts.html That might narrow it down.
I have a 350 warrior with a full big gun exhaust a uni air filter with a 3in x 3in square cut in the lid with a screen. My question is how do I jet it for that stuff is there a kit I buy or just certain jets?????
You can adjust per the specs of the exhaust and filter, but once you start cutting holes, you will have to jump to trial and error. No one has specs for "custom" modifications.
Partzilla I’m pretty sure I’m running lean my plug is white ish and my header was glowing red at idle yesterday for a cold start so what do I do put in bigger main and pilot jet???
If you buy a kit, you can test them. Sounds like you need to go up a size or two.
Partzilla Yea I’m gonna try that. And I just rebuilt my quad last week I just finish my first tank I been babying it my question is could I have damaged anything running it lean like that??? And is it bad that my header was glowing red?? Thanks for the help.
I just got a new carb and put it on but one of the black hoses just leaks gas out of it any suggestions
Is the hose damaged or is it draining fuel out of the drain hose?
it drains out the end
Float could be stuck.