03 wr450 jetting advice

I just bought a 03wr450 and made all the free modes to the bike. I drilled the starter jet to .028 and soldered the leak jet and redrilled to .018 in hopes of improving the starting when using the electric starter. Since doing that it starts great but it dosnt have that responsive snap at low rpm. Does anyone have any suggestions.

Did you move the needle clip any? I just installed a 48 pilot, 155 main, Zip-Ty fuel screw and moved the clip to the sixth position. Standing still at idle I still get a bad hesitation when I snap the throttle but not very bad when riding, just enough to notice it. Before these mods it had one of those "ouch this is gonna hurt" :) low end hesitations while riding.

There also was a thread about adjusting the pump screw in order to relieve the hesitation. Anyone remember who posted it?

you might try the settings in my signature line, I do not have any hesitation at all, just the hang on for dear life when you twist the throttle :). I didnt do any mods to the starter jet, most of the mods needed on earlier models of the WR are unnecessary on the O3WR450.

A fast idle setting always helps.

No I havent moved the needle clip at all. The local shop told me that the sj and leak jet work together and you cant make changes to one and not the other. Is this true?


gray wire, yz throttle stop, air box snorkle, stock jetting

i think the info you got was for the older wr's. it's not a problem to increase the starter jet size for cold temps and not change the leak jet on the wr450. there is no reason to drill out jets and solder and drill others. the dealer can get the correct jets. the starter jet controls the amount of fuel used when the choke circuit is used. if it's cold where you are, try a 72 starter jet. go back to stock when it warms up. (above 50f) with the ignition off and gas on, twist the throttle three or four times before starting. that should make the bike much easier to start. go with a 48 pilot and stock leak jet. as 5spoke posted, don't be tempted to turn down your idle to much. the manual calls for about 1700 rpm.

now about that needle, glue feathers on it and use it as a dart. they're terrible. the stock needle is for a choked off intake and exhaust, retarded ignition curve, and 85db's. it may look like an advertisement but there is a reason so many guys use the jd needles. it will cure the low end bog. you might have to play with clip position a couple of times to get it "perfect".

Do yourself a favor and buy the JD jetting kit! It will save you a lot of time and frustration. JD is very willing to answer any questions also. I PM'ed him several times here and he always answered my questions quickly.



With the way you have your jetting set up, do you ever have any mis-starts after it is warmed up? I did all of the unrestiction mods and kept the stock jetting all last year, which ran fine except of the occasional fumbling starts. I race Hair scrambles, and twice last year I was one of the last off the line due to it not starting immediately. Lately, I did try just the bigger 72 s.J. at 1-3/4 turns, but it seems crappier at low end and starts too rich. I will happily change over to what you have if it makes all of these issue go away. Thanks!

Starter jet is for when the choke is on. It has no impact on the bike while riding. Pilot jet. is where you may want to change. Try and determine your air screw setting 1 turn out to 3 turns out to determine which way to go with the pilot. If you prefer something between 1 and 3 turns stay with the existing pilot. :)

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