00 WR400 carb mid case seal availabilty

Took on this project for a friend thats now turned into the usual nightmare.. 00 wr400 with a carb bowl full of green death. I've been able to get the carb bowl and jets clean, but my accelerator pump nozzle was plugged with gunk and not responding to my efforts to clean it. I was pretty much forced then to seperate the middle section of the carb to get at the passages in there. What i've found is all the black rubber seals are disintegrating and the rubber particles are plugging things up..The yamaha parts fiche does not even show them and after hours of searching on ebay and this forum, it seems the yamaha version of this carb has some unique seal shapes.. The mid case sealkits i see on ebay from K&L look real close but not exactly 100% right.





this second kit actually lists the 2000 wr400 as one of the bikes it fits ..





there kit says this 

The gaskets will not fit Yamaha model years 1998 thru 2002.

Called tech support at sudco today and they said Keihin refuses to allow anyone access to those mid case seals because they feel its too complicated to service them and only alternative is a new 600 carb. I'm gonna take a shot at making those k&l midcase seals work. The center bubble gasket and vent tube tower square seals look the same. The 2 maicase seals are a little different shape around the perimeter thamine but the 2 center oval seals look like they might work.. My perimeter seal looks ok the inn er 2 oval seals are messed up. I'll razor blade the 2 inner seals off the new ones and try to reuse my outer portion.


Foud this pic online (all credit to James Dean ) that describes my issue exactly . My seal is shaped like the bottom one.



Edited by Gen2


I was able to save this WR 400 carb with a little luck and inginuity


On a hunch, after studying the pictures of the 2 mid case seals available from different sources, i was pretty sure the outer perimeter portion of the large main seal was not going to fit properly, but after looking at my mid section seals outer portion, i felt mine was definately reuseable.


My inner oval shaped seals were the ones that were destroyed. Fuel is in direct contact with these 2 inner oval seals. The large outer portion of the seal is more of a dirt/dust seal between the carb sections and never makes direct contact with fuel.


So i ordered both available seal kits from jdjetting and once i receaved them and laid the new seal against my old,  i could definatly see the outer perimeter shape is not the same. But the 2 inner seals would work !!!


So with magnifying reader glasses on, i used a sharp straight pick to work the slimy sticky old inner seals out of there grooves. Then cleaned residue with a small brass brush.


I cut both inner oval seals off the 2 main seals and matched up 2 that would work .! Yahoo.!!


The 2 inner oval seals are not the same on each main gasket. Out of  each pair, one would be slightly longer . I needed the 2 hole oval seal off of one main gasket since it was longer, and the 3 hole main seal off the other main gasket since it was shorter.


The "bubble seal" and the 2 tower seals that came with the kit fit perfectly with no problems. 


To be sure the oval seals would stay in place during carb assembly, i took a tube of black 3m gasket adhesive, and put a little drip on a peice of paper and smeared it around with my finger to about the size of a quarter, set the inner oval seals, one at a time into the thin layer of adhesive then quickly lifted it out and pressed into into the midsection grooves. It worked great..


Got it together tonight and rode it around awhile. It rips ! No bog, no hesitation, instant throttle response..


Hope this helps someone who is in my same situitaion. $63 total invested from JDJetting and didnt have to buy a $600 + carb .. :ride:


You have some extra tower seals left over and one whole main midsection seal left over too. Have to order both kits to get all the seals you need.





Edited by Gen2

I'm glad you managed to get it to work. If you did need a new carb there are various options other than $600, FlowPro advertises fully rebuild (and upgraded) carbs on SMJ for 350EUR usually, obviously not cheap but significantly cheaper than a brand new one. 


I suspect a main cause of your problems was Ethanol, if you can get gas without any in it you should even if it costs more. Around here there's no other choice.

I ran into that same problem with an '01 250.  I did what most do for that and bought a carb from a newer bike.  I managed to get a carb with cables for $75.  The mid body seals were available for later years.  

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