Carb leaking

Hello everyone,

I just brought home my first dirt bike in 2 decades an '02 XR400. What a beaut !! Anyway, got home, unloaded the bike ,took the bike for a quick spin on the yard. Ran fine. When I parked it in the garage, I notice that a significant amount of gasoline was comming out out the carb fuel drain line. I had to shut the gas valve off the stop it. I have a basic understanding how a carb works. My first thought was that the float was stuck. I'm not sure how to proceed. Any ideas ? I would love to hear from you.

Also, got any advise on what manuals to buy?? I already have the Honda Service manual.



I would try and tap the side of the carb with a screwdriver handle first. The float might be stuck and might come free when you do this. Keep it simple first.

i have the manual in pdf form..its 100 mb so too big to email. i can send you a CD if you want... just PM me.

in teh mean time, your float is stuck. you probably have a small piece of dirt stuck in the valve (a rubber nipple looking thing on the top of the bowl). just take apart the carb and inspect. in the process of doing so you will probably dislodge the the particle.

try parking the bike leaning against a wall (this will make it more level)to see if the gas stops leaking

if it does it could be as you said float level .

OR it can be a piece debris in the needle jet seat , it can also be that if there has not been fuel in the carb for a while the rubber tip of the needle jet may have dried up.

Try running it outside up curbs and stuff, as the typical screwdriver may not do the job. Happened on my old XR250 as well.

I've tried tapping with no sucess. I'll be taking the carb out next. I'm sure that once is out the problem and cure will be straight forward. Do you guys replace the bowl gasket every time? have you found a source for them without having to buy the entire gasket kit?

just be careful with the gasket and you shouldnt have to replace it. if worse comes to worse use a petroleum safe RTV gasket sealer in place of the old gasket.

I've tried tapping with no sucess. I'll be taking the carb out next. I'm sure that once is out the problem and cure will be straight forward. Do you guys replace the bowl gasket every time? have you found a source for them without having to buy the entire gasket kit?

Bit of dumb idea but has worked for me on my 250 more than one time when it had the same problem. Mine spewed gasoline everytime the engine is idling

maybe it was leaking even when i was running but hey! there was nobody on my tail to notice it :p

I used to remove the fuel line from the tap and blow air into it while pulling on the throttle... This has worked for me about 3-4 times... I assume that this dislodges any dirt particles that are not letting the needle jet seat properly causing the overflow...

Downside is that you get gasoline breath :applause:

just my 2 C :ride:

Ok, the carb is out (piece of cake). When I took the bowl apart the problem was evident. A entire bowl is lined with gas residue and a smal hard piece was jamming the bowl valve. The previous owned left the bike sit around for too long and dried up the carb. I sprayed it with regular, highly flamable, carb cleaner but it did't do much. Any recommendations for an effective and perhaps non-flamable carb cleaner? I'm guessing I will have to take it apart even more and soak it for a while? I'll be buying the gasket kit tomorrow since the bowl gasket was also cut and patched. Is there anything in the carb that I shouldtakeapart for a good cleaning?

I almost forgot, I took the muffler off, and the manual mentions replacing the muffler gasket (where it connects to the header). How do I remove the old one, which is well seated inside the muffler?

Also, those little hose clamps that Honda loves to use are a btich to take off. What is the proper tool or technique to loosen them and get them out of the way?

Tia for the info



I have the exact same problem on an 2002 XR250. The guy I bought it from left gas in it for a long time time and was ridden very little. I think the carb is similar. I have taken the bowl off and there is gas residue all inside the bowl. Even fine little particulates. Not sure if this was a good idea, but I poured some carb cleaner (the kind you use in a car) into gas tank and ran it through using the drain screw. Idea is to let it sit up for a few days to desolve the residue. I want to remove the carb keeply and clean as you did. Was the carb hard to remove?

The carb was easy to remove, you just have to follow the directions from the Service manual or Clymer to the T and you'll be fine. I was a bit intimidated at first, because you have to remove so many components to get to it, but is really no big deal. I remove the seat, the side panels and the the subframe and the mufler. It took me about an hour but if I had to do it again, it would prob only take about 20 minutes.

For the subframe, afteryou take out the top screw, just loosen the bottom ones instead of taking them out. As soon as you loosen them the whole thing will swing out of the way.

I had the hardest time with the little spring clamps that all the hoses have, they area real bitch to take off. I guess you have to have the right tool. I wish I knew what tool that was.

My Honda mechanic, told me that he uses a purple cleaner, such as purple power to disolve all the gunk. Apparently works very well, but it is caustic, so you cant let the body sit on it for very long and you must rinse it very, very well.

Yesterday, I bought a paint size can of carb cleaner at Advance Auto PArts, which is non-flamable and it includes a basket to soak the parts. I plant o take the carb apart this weekend and soak it well.

You will have to buy the gasket replacement kit forthe carb (around $23 from Honda) and the mufler gasket.

got to go to work, good luck.


While you have the carb off, take a look at the pilot jet. They clog and gum up easily due to the small passageway. I usually use carb cleaner to remove dried up gas from the jets and float bowl, but on really bad cases have used paint stripper (Kleen Strip). If you use the stripper, don't leave it on very long and clean it off completely with soap and water. However you clean it, spray some carb cleaner into the passageways (jets, float and slide assembly removed) and blow it out with compressed air. If the carb is exceptionally cruddy,soaking overnight in parts cleaner and then blowing out with air is also effective in most cases.

Was able to get the carb out in about 30 minutes. 1st time. Anyway, removed bowl and it was not all that dirty. Removed float pin, then removed float assembly to reveal the float valve. Looked fairly clean, no sign of damage or scoring. Look back up inside the carb through the hole where the float valve rides in and found a fairy good sized piece rubber (maybe from fuel line???) lodged at the top. I pretty sure this is my problem, as the valve can't close all the off with this peice in there. Anyway I'll do a good cleaning and report back after I get it back together.

That is the exact same thing that my 97 cr250 done.I"ve been around bikes all my life so i knew what was up right away,hell,one of my best moto head buddy"s own"s the motorcycle shop in my home town.I loosened up the carb and twisted it sideways and pulled the bowl (you can get away with this on the cr) sure enough,there was a small piece of plastic that had shreded off the fuel line,it had to come from the line because it was the same color.Anyway i blew it out and ooops,dare it is!Mucho Gusto XRRon

My XR400 was dribbling out the overflow vent.

Yet another vicitm of debris in the carb.

Seems pretty common with this carb.

You might want to replace the fuel line and clean out the gas tank if you thing the fuel line caused the problems.

You'll enjoy the XR400. A fun bike. :applause:

Spring clamps are no problem with a regular set of needlenose pliers. You grab them from an angle and then squeeze as the clamp turns in the pliers. If you did it right, you will be holding the clamp open with the ends flat in the pliers. It takes a little practice, but it's really easy once you figure it out.

:applause::ride::p Amigo, Pull that carb and soak it in some Gunk or other parts house de-greasers,if need be,you can push out the small passages with a tip cleaner from a cutting torch,and lets not forget,the trusty old air compressor! XRRon

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now