WR400 Replacement Carb

I have a '00 wr400 and I'm sick of it gumming up and having to work on it every spring to get it half way rideable.

It has the "won't run without choke" & "no idle" issues. (I've soaked and cleaned which helps for just a little while, maybe a month)

I have added a fuel filter, stabilizer, run the carb dry, etc...frankly, just tired of working on it and want to ride more than wrench.


Is there a recommended replacement carb for this model year?



Any carb you use will have the same problems.


You just need to clean it correctly once, and then always treat your gas and empty the carb of all gas before storing. 


The carb from the WR450, any year, is the go-to replacement.

I'm not sure if other carbs will work with it due to the throttle sensor that plugs into the carb, but then again I've never tried it before... As for my wr426 I've had the same problems, and I just go out and start it every 2 weeks, let it warm up with the choke on, then take it for a 5 minute ride, running it at low Rpm's, then sparratically giving it gas and doing wheelies... Until it runs the way I like it, then I put it up and do the same thing on the next best day... It's hard in the winter with the cold weather and all. But that's the best way I've found to keep from having to wrench on it...

The TPS is not critical on these bikes

You can dissconnect it if you want

When it comes to fine tuning the ignition curves, the TPS comes into play

Since the WR curves are so messed up anyway, many leave the TPS unplugged forever.

Thanks for responses.  I suppose I am spoiled to my XR650R(the AK47 of reliability, but heavy).


My existing WR carb has been poked and prodded so much by others trying to get it cleaned that I will probably look for a WR450 takeoff.

What jetting mods would be needed for a WR450 carb on a WR400 (riding in MO, roughly 700-1000 ft elevation, w/ YZ mods)



ncvs needle

50 leak

tokyo mods apump linkage spring

short rivet apump diaphragm (2007 crf450r)


..better than Fuel Injection

Sweet, thanks!

check the tank with a flash light for brown goo- if the gas has gone bad, the problem may be lurking in the tank. So even though you cleaned the carb, sludge sits on the bottom and goes right back into the carb. 


I learned this the hard way-

Edited by Team_Oatmeal_Pie

...and pull the clean the tank petcock and screen

And the fuel line.  Learned the hard way.

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