Just bought a WR

Just bought a 98 wr400f, need some info please. Can the grey wire mod be done on this year? Can the BK mod be done? What are the things I should look out for? Any help would be appreciated!

I bought a 98 WR400 in December and have done quite a bit of research here on TT and at thumperfaq.com.

The standard "free Mods" follow:

1. Remove the air box cover. (More air to carb)

2. Cut back the throttle stop. (More air through carb)

3. Remove the exhaust baffle. (More exhaust through pipe)

4. Disconnect the grey wire for the CDI unit. (Change spark map to YZ for mid/top range performance)

5. Disconnect the blue wire from the neutral switch. (easier starting)

6. Re-index exhaust cam for YZ timing. (Change exhaust cam timing to YZ for mid/top range performance)

Not free mods to consider:

1. Exhaust insert (too loud without something in my opinion and most states have db limit in 94 - 96 range) GYT-R or Pro-billett make good inexpensive options.

2. Change to new pipe all new pipe.

3. James Dean jet kit. (well worth the $70 in my opinion)

4. '03 exhaust cam with auto-decompression. (No more finding TDC and lever drill)

5. Zip-Ty or other fuel screw.

That's a good start and I'm sure that you will get more advise as time goes by. The first 3 free mods are a must! My friend was with me when I bought it and rode it recently with the first 3 mods and doesn't believe it's the same bike.

I have not been able to find a dealer that can get the YZ throttle screw for the 98 and the newer version does not work. Be careful when you cut the throttle stop, don't take too much off.

Also, the same applies to the fuel screw and the carb mods listed on the threads. The 98 has an earlier model and you need to make sure that you buy parts or do mods for the early model.

Most of the information for all of the above can be found on thumperfaq.com or here on TT. The thumperfaq site is mostly WR250, but just about everthing listed works for both and there is a lot of other info that may be of value.

Lastly, I have been slowly doing the mods to my WR and if you have any questions let me know and I will help if I can. I haven't been in too much of a hurry because the first 3 free mods and the GYT-R exhaust insert made the bike faster than I can ride it. Still not sure if 5th gear works, I never get there!

Well, checked and the throttle stop screw has been done, the exhaust has definately been done, but not the air box. Also, after riding it this weekend, I noticed that if you wack the throttle to wide open it bogs bad, but only at low rpm, if you wack it at mid rpms, it gets up and moves. Also had some problems with it dying when climbing, maybe the grey wire has been pulled and I just need to ride it at greater rmp? Any suggestions? I ride at between 3500 and 8000 feet above sea level. Very happy with the ride though, lots of power, no weight. Also, my last bike was a 1981 xr500r.

The bogging at low rpms sounds like a jetting problem. You may be too fat on the needle jet. Try leaning it out by moving the clip up one notch and see what happens. Opening up the air box may also help lean it out.

Hey tcmII,

Staying Dry??? I saw you were from Macomb, MI. I live in Clinton Township. Luckily I didn't get flooded out this past weekend.

I just bought an 02 WR426. Love it. I have to check for the gray wire to see if its been disconnected.


Quote :lol:isconnect the blue wire from the neutral switch. (easier starting)

would this mod also apply to a 02 WR426.



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