E K P Neddle

Hello all,i'm posting this ? to you even though I know much has been discussed. I read all in the archives that I could find on it,but felt inclined to throw it out there again.It looks like most guys with 400's are happy with a clip setting of #3 or #4, and main jet of 170 give or take two either way.My air box is opened up a bunch,and I run a Pro Circut T4 exhaust.I kept seeing James Dean's name in all these post,I guess he really is "the man".I would lie to know if these adjustments are still the way to go,and would like to know if I should start messing with the main air-jet needle? Now comes the partI hesitate to type I am a DRZ 400 owner not a WR 400 owner.It's just that I've heard too much good info over here,and I like to tinker and want to get everything out of that engine I can.Thanks for your time. Alex

The two foremost experts on jetting James Dean and Taffy. Both usually hang out on the WR side. Not sure about the DRZ but, the latest needle craze is the EMM or EMN for Yamahas.


The EKP and EKN are 1 clip position richer than EMP and EMN respectively, so clip EKP#3 = EMP#4. The YZ250F and YZ426 use the same profile needle (EJP/EKP). EMM is a step richer than the EKN/EMN.

Any of these will work to increase your mid-throttle power over a Dxx needle with a little tweaking on the clip position. The main jet gets reduced if anything and the pilot stays close to the same.

We spent some time playing with the Main air jets a long time ago. Taffy liked the smaller #160 and recommends it with a smaller main jet, while I still prefer to stick with the #200 that comes stock in all the FCR's and adjust the main jet only. I was mostly riding the '00WR400 with a YZ exhaust at the time.

If you search the DRZ forum, there are riders using some of these already. The most likely needle codes to search on are: EKP, EKN, EMN, or EMM

There are also the less commonly used but equivalent: EJP, ELP, EJN, or ELN


Thanks Bill and Of course James for your responce.I did get one responce from a guy on my side of the fence,he said his did the exact same thing as mine(too much fuel),at roughly 3/4 throttle.He had a 168 main,andchanged it to a 160 main.He also did the Taffy mod,he rides at 3000ft,but he says it rips!Once again thank you! P.S. would James spread sheet have helped me here?For us who like to tinker is it worth possessing?

The spreadsheet helps keep track of all the needle codes so you don't start buying things you already have. It also helps see the interaction with the main jet and needle taper. Your opened up airbox may take different settings along with the T-4 exhaust. EKP#3 with a #xxx main jet is a good starting point for your DRZ.

***** After reviewing the posts on the DRZ forum, and seeing that smaller main jets are the norm, try a #160 main jet first.***********

See: www.JDJetting.com


[ July 11, 2002: Message edited by: James Dean ]

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