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Wr 426 YZ timed, Planned Jetting

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I recently changed to YZ timing and had some jetting problems. I got educated enough to know what to look for on a search. This is what I decided to go with after a good seach of past posts.

100 PAJ

48 PJ

200 MAJ

EKP Needle Start off with #4

For anyone with a YZ timed WR 426, am I in the right ballpark?

I tried to find where the EKP needle comes from, I assume it is from a 2001 YZ 426. The two online parts fish I know of do not list all the needles for the 2001s

The only mods done to my bike are: Air box lid removed, YZ throttle stop and B.D. baffle

[ November 20, 2001: Message edited by: finglan ]

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Couple of points...

I dont think they make a main jet at a 200...and I believe that would be the equivalent of you pouring gas out of a gas can directly into the carb. I think you probably mean to say 200 MAJ (main air jet...stock air jet as I understand it). You might go back and check what other NY folks are using, but I'm guessing somewhere around 165/170...

Also, I tried (and failed miserably!) using a larger pilot jet. I'm now back at a 42PJ/75PAJ. In "Jetting ?'s", Taffy lists the following combinations of PJ/PAJ's being good combinations to provide you with 1.5 turns on the pilot screw:

48PJ 100PAJ

45PJ 100PAJ

42PJ 85PAJ

40PJ 85PAJ

38PJ 75PAJ

35PJ 75PAJ.

I'd try one of those as a starting point...and get a Pilot Air Screw (PAS) from Sudco...$15 or so and you now have a completely adjustable pilot air jet anywhere from a 65 to over 120. Also, get a Kouba tool (do a search for the website) to provide an easily adjustable pilot screw you can play with while you're bikes running. Another $10 well spent...

Finally, I had the same problems ordering jets...it's a very frustrating thing when dealers are telling you you're wrong! Problem is, the parts microfiche is often wrong. James Dean helped me out again in "Jetting ?'s" listing the following part #'s for me:

"Part numbers were correct in the '00YZ426 service manual only-


OBEKN P/N 5JG-14916-EN

OBEKP P/N 5JG-14916-EP

OBEKQ P/N 5JG-14916-E1 (NOT EQ)

The newer '01YZ250F has needles which shift the clip position by only 1/2 clip and are correct in the fiche.(EKN#3=ELN#3.5, EKP#3=ELP#3.5)

OBELM P/N 5NL-14916-EM

OBELN P/N 5NL-14916-EN



ONLY Yamaha will have the OBxxx needles listed above. They are a hard coated/plated aluminum.

Sudco ONLY has OCxxx, brass needles, which are less expensive (~$8). These are another 1/2 clip leaner. (EKN#3=ELN#3.5=EMN#4)






You might consider ordering the EKN and ELM jet needles as well, as it sounds like several of the "lowlanders" out there are running these (FYI...I'm going to try an EKP and I'm at 7500 ft.).

Hope that helps!


[ November 20, 2001: Message edited by: LarryCO ]

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Thanks for the info and part numbers. The MJ was a typo, must be the dense air down here :)

Are the EL( YZ 250F ) series the same as the EK series w/the exception of being able to adjust by a half clip instead of a full clip?

[ November 20, 2001: Message edited by: finglan ]

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I lost all of my e-mail addresses when a coworker reformated my computer.

Thanks for the info. It is exactly what I was looking for, good jetting specs from someone in NY. After a search and some help from Larry your specs are what I was going to use. It is nice to get a conformation from a New Yorker. Our conditions should be very close. I have all the jets on order.

I transferred my VT plate to NY yesterday. My bike was also registered in NY as an atv. I explained that to the DMV and they never balked nor questioned that the taxes were already paid on it. I paid my $23.25 and walked away w/a plate and reg. card. I should get my "motorcycle" title in sixty days. The Michlien tires are holding up great. I pounded the hell out of them over a 100 miles and there is NO sign of wear. They are fair on the road and excellent in the dirt.

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