Used 1999 WR 400

12 replies to this topic
  • timvv51

Posted October 21, 2003 - 06:00 PM


Hi I am bidding on a used 1999 WR400 that is on Ebay and is 350 miles away. All I have seen are pictures and it looks pretty clean and the seller says it is a good bike. Would anyone care to give me some advice on what to look out for on this old of a bike. These bikes could be a bear to start if the got flooded couldnt they. I have owned lots of bikes and currently own a WR450 but have no experience with a 1999 400 Will a YZ rear fender will fit on it? What I am looking for is a good used 4 stroke in the 2500 dollar range for a son. Thanks. Tim


Posted October 21, 2003 - 07:16 PM


All of the YZ Plastic will fit perfect....You can put the YZ Tank & Seat on it as well. I have one of these bikes, and the only thing that I felt needed to be updated was the clutch...I put a 426 complete clutch into it. I had to replace the covers so the larger clutch assembly would fit, but it works well. If your son is racing, or is an aggressive rider he will burn up the stock clutch.

I later installed the 426 Rod & Cylinder, and did an .80 Over BIG BORE, I use the YZ Timing ,and it runs great, it measures out to be about 444cc. :)

  • jchantzWR400F

Posted October 22, 2003 - 06:21 AM


I've got a 99 wr400. Great bike. Just change the oil. Do the free mods if they are not already done. Very reliable bikes IMO. I paid around $3200 for mine slightly used in March/April of this year. Bike was cared for very well. I have not regreted a cent of what I spent on this bike.

  • daleb

Posted October 22, 2003 - 07:38 AM


I am aking delivery of a WR400F very soon, what 'Free mods' need doing ?



  • MOmilkman

Posted October 22, 2003 - 10:28 AM


If your son is racing, or is an aggressive rider he will burn up the stock clutch.

Why would you have to replace the stock clutch unless someone has abused it? If you dont ride the bike like a two stroke then the clutch will be fine. The only time I have had to ride the clucth a little was on a extremely steep hill climb to keep the front end down.

Mines a 99 and still has stock plates.

  • jchantzWR400F

Posted October 22, 2003 - 10:53 AM


you can do a search for "free mods" and that should help. They include, Shaving the throttle stop, Opening the air box lid, and uncorking the exhaust. Also, most people cut or disconnect the grey wire coming out of the cdi box.

I think that pretty much covers it. Rejetting the carb will be necessary, but it is not a free mod.

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  • MN_Kevin

Posted October 22, 2003 - 11:20 AM


You can also modify the accelerator pump to mimic the BK mod done to the 2K and newer bikes.

There is my own mod, and there is the Taffy Mod for the 98/99 accelerator pumps. Both work, although the Taffy mod is not intrusive to the carb body as my mod (KL mod) is.

This sets the duration of the AP squirt. Stock, the squirt can last up to 4 seconds, which is waaaaaaay too long. Generally, 0.25 > 0.5 seconds is optimal.

There is also the blue wire mod which cuts voltage or something if the bike is in neutral. Reports have indicated cutting the blue wire eases starting.

  • MOmilkman

Posted October 22, 2003 - 01:04 PM


Reports have indicated cutting the blue wire eases starting

I did this mod about 6 months ago and I can attest that it does work. I used to foul plugs all the time when the bike was warming up. But it hasnt since.

And instaed of cutting the wire, Kevin means "unplug it" :)

  • MN_Kevin

Posted October 22, 2003 - 01:46 PM


And instead of cutting the wire, Kevin means "unplug it"

You can cut the wire right at the neutral switch near your countershaft sprocket. If you trace the wire to the harness under the tank, you WILL find all the leads off that harness are all DEAD leads. I removed the netral switch gizmo at the engine, used a Ty Davis billet plug to plug up the hole, and disconnected the wire harness under that tank.
I did this while re-wrapping all leads after installing the coil on plug setup (~$50) from Mike Dean out of Wisconsin.

  • jchantzWR400F

Posted October 22, 2003 - 02:04 PM


I have not done the blue wire yet. Any explanation on exactly what benefits and why?

  • MOmilkman

Posted October 23, 2003 - 05:50 AM


I have not done the blue wire yet. Any explanation on exactly what benefits and why?

  • jchantzWR400F

Posted October 23, 2003 - 06:48 AM


Thanks for the link Darin.

I have never fouled a plug, and it seems to start pretty easy. But it doesn't sound like it will hurt to try the blue wire mod. I let everyone know if I can honestly notice a difference.


Posted October 25, 2003 - 08:58 PM


The smaller clutch heats up and begins to slip....Yamaha addressed the problem on the 426 and used a larger clutch. Nothing to do with abuse, and most riders will never experience a problem, I actually did't notice myself. I loaned this bike to a pro level rider to race at Mammoth MX. The clutch would go about three laps before starting to slip. Changed the complete clutch, and never had that problem again. Actually finished the race in 2nd Place open 4-Stroke! NOT ME...The rider..I'm too old...too slow...too fat! :)


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