Jetting Help Please!!

Ok here is another jetting question. I have done a search but can't seem to get what I'm looking for. I have an 01 426 , it's been YZ timed, air box lid removed, and has a full Yoshimura system on it. No other mods. I ride at 4,000ft to 7,500ft. Can somebody please give me the jetting specs for this set up. Thanks for all help :)


What you have there is a YZ motor in a WR bike IMO.

It is much warmer down here but at 4,500 ft. I ran the following on my '00 and '01 YZ, and also changed this for two friends' '01 WRs, one WR timed WB exhaust, one YZ timed stock/uncorked (both no lid, cut throttle stop):

EKQ #3 (Yamaha PN: 5JG-14916-E1)

160 Main

200 Main Air Jet (stock)

40 pilot

~ 85 Pilot Air Jet (stock is 75, should be okay)

~ 1.5 turns out on fuel screw

We went on a four day ride at Rampart range up in CO in the summer, that riding area averages about 7,000 ft probably, and I went to a 38 pilot, 158 main and another clip pos. leaner on the needle and my bike ran great. The two WRs on the trip did without the smaller main and pilots and ran acceptably with just the leaner clip pos. on the needle.

Changing to a YZ needle is a big improvement for any uncorked/uncovered WR 426 IMO, I've probably made 100+ posts recommending some type of YZ needle to any WR owner who would listen... :)

Hope this helps.

Thanks Hick. I don't think many places up here know much about running the YZ needle. What position do you have it in?

What position do you have it in?

Third from the top.

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