Do I need to change Jetting for my Y2K WR400 W/O Baffle elev.900ft or leave it stock?

I have asked this but thought that I worded the topic wrong. I have done nothing to my 00 WR400F but removed the baffle from the exhaust I haven't ridden it this way yet do I need to change the jetting?elevation is 900ft. thanks for any replies!


Mike from Oregon

Hey BHE:

I ran my stock jetting (99 WR So. Cal 0-3000ft) all stock with just the airbox lid removed and it ran just fine. Mine is a Canadian model and the baffle doesn't come out.

I put a YZ pipe on and it still ran pretty good, but it popped a bit with the throttle off and seemed like it was running a little hot (lean). I didn't ride it much like that and didn't bother messing with the air(or is it fuel :) )screw to try and fix the popping.

I went to YZ timing and jetted it per the recommendations posted here and now she runs sweet.

I suspect you would be fine with the stock jets. I saw at one entry in the jetting section that was running stock pipe w/o baffle and stock jets in Arizona (low altitude, but dry).

As always WMMV and you should take some plug readings, etc, to be sure. If you haven't already tried, check out the Technical section and also do a search of the General Discussion, there has been a lot talk about jetting around here.



BHE- Yes, you should probably rejet. Check your spark plug for grey or white (lean), tan-OK, or black-too rich.

The 98-88 jetting does not work for us, but it is close. You ride in Oregon- a wet place, right? 900 feet isn't too high.

What are your symptoms? I had to goto a 45 pilot and 172 MJ, 4th clip stock needle with the snorkel removed and exhaust tip out(600-900 feet ohio, 65 degrees). Otherwise I had a high idle at no load, would hesitate and lug on the bottom end, popped when chopping the gas.

Make or buy a 3" small tip screwdriver to adjust the pilot (fuel) screw. Clockwise is leaner, counterclock is richer.

I bet you it will run better just by turning the pilot out. Turn it 1/16 turn at a time, a little is a lot. Then move up to a larger MJ-maybe 168-170. Do a spark plug test again.

The needle clip may also have to be adjusted or even a new needle entirely.

The actual work of changing jets is a piece of cake, don't worry about that. The process of checking the spark plug and riding it between changes to feel for differences takes a while. good luck

I would say yes, it will run fine w/o the baffle, you do not need to change the jetting. Mine runs perfect just like that.

Thanks everyone for the help I'll try riding it with the stock jetting and see what happens. Thanks again!


Mike from Oregon

Whatever you guys say; rejetting really helped my bike come alive :) Thanks to all the folks on this site you helped!

I rode my 98 wr400 for about nine months with the air box lid on and without the baffle, wr timing. I messed around with the jetting a little, only to find out that the stock jetting was right on. 0 - 1000 ft, Illinois. However, I noticed removing the air box lid definately leaned the bike out and requires richer jetting. Bottom line, you shouldn't have to rejet just because you removed the baffel.


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