Some ideas on jetting for a 99 wr400


my wr is all stock except for the baffle is out, I live in western PA. I'm just looking for soom info on jetting to max out the power and performance on my bike.. has a dead spot on the crack of the throtle.. and builds rpms slow...

all post will be helpful

I have a '99 with the stock exhaust with baffle removed, airbox lid removed, and YZ timing. I use a 178 main and a 48 pilot, stock needle, stock clip position and it runs terrific. I never have any starting problems, either. I ride in middle TN and north AL, I think the elevation is 500-1000 ft. Hope this helps.

Roger Little

'99 WR400

Your jetting is all going to depend on time of year(hot, humid, cold, dry variables), altitude, what mods you have made. Your hestation may be caused by a dirty accelerator pump, clean it and see what happens. Also count how many turns out you fuel mixture screw is and write it down, then try 1/4 turns out and see if it clears up the hesitation. I am currently running two turns out on the fuel screw and have all but eliminated the hesitation, of course this is just one variable, and each bike may be a little bit different.

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