99 WR400 Leaking Carb Problem

[fadingfastsd]

Hey guys, I've got a problem I can't figure out.

I searched and read all the leaking carb threads I could find, and all had the same basic info.

I've got a 99 WR400, with the Kehin FCR (pos) carb.

As soon as I open the gas valve on the tank, wait a minute for the bowl to fill up, the carb starts a steady large drip out of the drain tube on the bottom of the float bowl. It will continue until I shut off the gas, and it drains the float bowl empty.

So, I pulled the carb today and went through the float bowl. Everything looks good. The needle valve is smooth and has no groove in the point. The valve seat looks good and smooth and clean. I sprayed it all out with carb cleaner and ran compressed air through it anyways. I checked the float level, which was a little off. The manual says 9mm, mine was around 7mm. I adjusted back to factory settings.

I put it all back together, turned the gas on, and 2 minutes later had a 1ft. diameter puddle of gas under my bike.

What the hell is going on!? If the needle and seat are in good shape, the float moves freely, there is not a spot dirt or gunk in the float bowl, the float is adjusted correctly....what the hell is allowing all this overflow!?

Any help will be much appreciated. I hate this carb, but after rejetting and a ZipTy fuel screw, I have it dialed in and working pretty damn well. I'm getting really sick of this problem though, and I'm about ready to junk the carb and get an Edelbrock rather than waste money rebuilding a POS.

Thanks!

Evan

[SXP]

Hey guys, I've got a problem I can't figure out.

I searched and read all the leaking carb threads I could find, and all had the same basic info.

I've got a 99 WR400, with the Kehin FCR (pos) carb.

As soon as I open the gas valve on the tank, wait a minute for the bowl to fill up, the carb starts a steady large drip out of the drain tube on the bottom of the float bowl. It will continue until I shut off the gas, and it drains the float bowl empty.

So, I pulled the carb today and went through the float bowl. Everything looks good. The needle valve is smooth and has no groove in the point. The valve seat looks good and smooth and clean. I sprayed it all out with carb cleaner and ran compressed air through it anyways. I checked the float level, which was a little off. The manual says 9mm, mine was around 7mm. I adjusted back to factory settings.

I put it all back together, turned the gas on, and 2 minutes later had a 1ft. diameter puddle of gas under my bike.

What the hell is going on!? If the needle and seat are in good shape, the float moves freely, there is not a spot dirt or gunk in the float bowl, the float is adjusted correctly....what the hell is allowing all this overflow!?

Any help will be much appreciated. I hate this carb, but after rejetting and a ZipTy fuel screw, I have it dialed in and working pretty damn well. I'm getting really sick of this problem though, and I'm about ready to junk the carb and get an Edelbrock rather than waste money rebuilding a POS.

Thanks!

Evan

Been there done that. The needle and seat are NOT in good shape. The rubber coating around the needle deteriorates with time and it's not quite evident to the naked eye. I fought that one for quite a while with both my 99s. A new needle/seat assembly (~$40) eventually solved the problem. BTW, I'd avoid getting carb cleaner on rubber parts (like the rubberized part of the needle valve) as it makes rubber swell.

Try sudco.com before you go to the dealer - quite a bit cheaper. Good luck.

[spidennis]

Well, it now appears I'm in the same leaking boat! I just installed an acerbis 6.6 tank and my float seems like it's stuck and not working, I got the same stinkin' puddle under my bike, dang........... I wanted to change out my leak jet anyway , here's my chance ......

[spidennis]

Is it possible to just drop the bowl cover to fix this stuck float problem ? or does the carb have to be taken out? I didn't see anything in the manual about this ....

I also have a #40 leak jet that I've been wanting to put in and wondering if all I have to do it drop the bowl cover to change out the leak jet.

Is this possible for both?

btw, I just washed the carb while on the bike before I started messing with all this, and now it's drying so I have some time to ask .....

[augino]

i had the same problem and just fixed my leak on my 2000 wr 400. the needle and seat looked goos so i removed the brass insert that the needle sits in and there was an o ring around it. i looked at it under a magnifying glass and found cracks. I replaced the o ring with a new one from one that i had on hand. done!

[spidennis]

well, had to turn the carb and actually pull it out from the airbox to remove the bowl cover. I did replace the stock leak jet easily enough with a #40 while I was in there.

Now my question is:

I want to check the operation of the float valve. so i put a piece of hose on the fuel intake and blew a breath of air into it and it flowed just fine, then I moved the float to the up/closed position and that stopped the air flow.

Is this a good test?

Since I was leaking fuel all over the ground, some part of the float had to be stuck, right? ..... and now I don't see any problem while it is apart......

guess I'll put it all back together again and see what happens .....

update: well, no more leaking ...... and the bike runs again, that's always nice to have happen! I still have the bog though ........

[H2OENG]

Remove the brass tube that the needle valve rides in. Your Oring is toast. I had the exact same problem, (just like Augino posted above). I went to every place in town looking for that Oring. Its a hard size to find. I eventually found one to work without paying the $40.

I have seen other versions (year or bike make?) that this piece is pressed in and there is no Oring. If yours is non removeable, I'd look closer at the needle valve. I found the parts blowup on Sudco.com to get the ring size.

Good luck.