98 WR400F jetting question for James

Hi James,

I have studied your jetting diagram with great interest.

Does the EK* series needle really helps to boost up the bike?

My bike is jetted in the following , showed in my signature. I'm riding at sea level, does changing to EK* needle have any different?

By the way, I have the stock main air jet though, will change it together with the EK* series needle. K or P for me?? :)


'98 WR400F, YZ timed, main:180, pilot:48, DVR needle 4th clip from top,

snorkel removed, YZ tank/seat combo, YZ front no.plate/rear fender,

DSP Ti exhaust system, Brembo front brake,steel braided hose, EZ clutch adjust perch,

Stroker billet rear brake reservoir

he's on holiday.

if he said it he meant it.

i ride at sea level on a 99WR

i run a std DXM needle on clip 6. tthis is fine but could be better.

my advice is yz iming, 100 air jet, std 45 pilot, 1 1/2-2 turns out on the pilot screw, i've bent the acc. pump arm (the one with two prongs) down & out so that the pump does less work.

he says the EKP needle is better, i believe him so try it. i find JD's settings a little rich so try it on 3rd clip.


The short answer-

EKP#3 or EKP#4 (Same as '01YZ426)

one step richer off idle to 1/8 throttle-

EKN#3 or EKN#4 (Cooler temp option)

The difference is like splitting hairs. :)


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