99 jetting, not there yet

I been all over the place on this jetting and something is still amiss. Basicaly, im at high 80´s, super high humidity, 160 main, red number 3 clip (yeah I know you´ve heard this all before, sigh...) I was running better I think at number 4 clip, but I got a pop on decel so tried the 3rd. At this point it´s giving lot´s of problems dying at low RPM when you lug it over stuff. Also, it dies while just sitting idling. Should I go back down to 4 clip? I had to go 2 1/4 turns out to get the pop to quit at number 4. What else should I be looking at? I know something is not yet right. Like when I dive into a hole and let off the throttle when I try to open it back up it sputters and cough... and im getting all fwusterpated.


I'm new at this whole jetting thing, but my limited experience tells me, and I hope someone will correct me if I'm wrong, if you're out 2.25 turns on the fuel screw you might try increasing your pilot jet one size. It may help the stalling at idle too. As far as the sputter and cough, it sounds like something I just went through. I'd expect you could correct that with a combination of leak jets and AP timing. Since you didn't say where you were with these I can't say which way you should go. I can't accurately say which way to go with the needle either, but I'm at sea level with the same 80's temp and ultra high humidity. Red # 5 worked for me. Also try raising you idle a bit too.

Well, thanks for the feedback, but I hope to get this thing at least halfway enjoyable with tailoring the main and red needle as leaks and pilots are hard for me to get here in SA. At any rate, I think what I need is to be at 160 main and clip 4, or 165 and clip or 3? I´m getting a gas headache.


Seems like your main is too small unless you have a 160 main air jet (maj)..I would try a 165 or 170 main with the red needle clip 4 from top. Also check the ap squirt duration..if it's more than 1 second, may be the cause of your problems. These bikes run very well too rich, but run poor slightly rich or lean, when their spot on.. lifes great :) . Good luck and maybe post this in the jetting forum for JD.. :)

Well, here´s what I ended up with. I tried to get the 165 to work, but even at number 2 clip, I could hardly get it to run more than a couple blocks without dying... lower was even worse. Could be that the top clip would have done the trick, but I was sick of trying to make the 165 work and switched to a 160 and went to 5 clip. At 5th the midrange was pure sputter. 4 was better, 3 cleared up the midrange completely. I do though have a slight pop unless I go to two and 1/3 turns out. I´m pretty happy where I am, even though with the 165 main, the very very top of the throttle felt a bit stronger than anything I can get out of the 160, BUT with the 165 I could not get the thing to run right at all. Any opinions on whether or not the 1st clip would be worth trying on the 165? At two it was just crap on the first 1/3 of the throttle. Unless you guys STRONGLY feel that the final jump to clip one would really do the trick on the 165 then I´m going to leave it be.

In all, despite the problems, the JD kit did for me what I needed it to do. I leaned it out enough to get my top end back, and the midrange was improved due to the better needle design. To be truthfull though, I think JD should go a bit farther in his info sheet on where to go when things don´t go quite right the first time around. How bout a general synopsis on jetting principles? Would not be hard for him and would have greatly sped up this process. Anyway, I´m good now, thanks.

Mark Sheldon.

99-400, no T stop, grey and blue wires, no blox lid, WR timing, JD red 3rd clip, 160 main (hot/humid), drilled out PMB insert, taffy mod, full Moto-Pro suspension.

my 99 wr400 has jd red needle 5th clip,170 mj,42 pj, yz exhaust,powernow, octapus is removed,all free mods,wr timing.i ride 500-1500 ft. 80- 90 degree temps.high humidity.it runs great,always starts easy hot or cold.

I messed with jetting for years. Tried every imaginable combination from extremely rich to extremely lean, different needles, clips, you name it. I have a quiver full of needles and a box of jets. I got sick of it and went completely back to stock (factory) settings and you know what? It runs perfectly now. Starts easily, doesn't overheat, no popping or bogging. I have a '99 like you. Do yourself a favor and go back to stock. There may be 2% more power in getting the jetting just right, but when you're that close, it always has to be messed with. I used to have my carb off every week adjusting something. It's been stock for over a year and I haven't had to remove the carb (or a spark plug) once since then.



Call me a crazy heretic... :applause:


your main jet was obviously too large-you answered that youirself. the needlke was too high, you answered that yourself as well!

all you need to do now is put all that together and take it to it's ultimate conclusion. a leaner MJ and then the needle can return to a sensible 2nd or 3rd clip.

then you'll be alright.

remember that i was on a 150MJ and when i went to a husaberg everyone was on 170s. enter Taffy!!!!

i have most of Husaberg UHE on 160s now and i'm on 148.



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