Jetting opinions

I keep getting different info about jetting for my 02 wr426. No mods but grey wire cut (thanks for that tip) and uncorked. Most of my riding is on trails at around 6000. Currently running stock (what the dealer told me). main 165, pilot 42, needle 4th, and airscrew 2 turns out. My bike has ran really rough at times and others not but always have a back fire when engine breaking. Plug looks sooty. Thanks for helping a newbie.

p.s. In Larmimer county it is closed unless marked open (long story) :):D

Welcome to the board. If you look in the search of the old archives, you will find a High-Altitude jetting thread from LarryCo. He did alot of testing out here and found that swapping the needle to a EKP in the 3rd clip position with a 38 PJ/65 PAJ and a 150 - 152 MJ and a 160 MAJ work pretty great out here.

Curt

I keep getting different info about jetting for my 02 wr426. No mods but grey wire cut (thanks for that tip) and uncorked. Most of my riding is on trails at around 6000. Currently running stock (what the dealer told me). main 165, pilot 42, needle 4th, and airscrew 2 turns out. My bike has ran really rough at times and others not but always have a back fire when engine breaking. Plug looks sooty. Thanks for helping a newbie.

p.s. In Larmimer county it is closed unless marked open (long story) :):D

Any opinion that does not include a suggestion to try a YZ needle, or other E-taper needle, is incomplete IMHO (my crusade against wacky WR jetting continues).

Hope this helps.

You have come to the right place. I ride 6-9K and have been working on my jetting; these guys like LarryCo, now LarryMN, Taffy and CuLayTur have been a big help. I went to a similar jetting that those guys use and loved it. It makes the bike snapper. I do have to lower my needle because in third there is poor response. If you go their route remember the EKP needle is only available from you Yamaha shop and most likely will take a week to get and they will have no idea what you are talking about, give them the part #, the Main air jet comes form sudco and make sure they know you want the main air, not the main. Let me know if I can help any more.

Hello,

I had a 2002 WR and I ride between Moab, Summit County and Denver, CO. I now have a 2003 WR. With the 2002, I dropped the stock needle to 3rd position from top (this made a huge differance), 38 pilot, 1 3/4 turn on the airscrew and 158 main for the front range and 155 for Summit County and Moab.

My 2003 greatly benefited from a stock YZ needle at the 4th position, 155 main, 42 pilot and so far the airscrew adjustment is TBD. The idle races high while I'm racing so I'm experimenting with solving this problem. Any ideas on how to make the idle solid? The idle adjusment is almost all the way in.

Tim

My jetting is in my signiture and works awesome! I have tried LarryCO's set up and couldn't get it to work on my bike. Larry and I discussed it and figured out that it must be because of mod differences such as the ACV mod (I've done it, Larry hasn't). Anyways, with my current mods and jetting, my bike rips! Note: do not go as lean as I am on the pilot circuit unless you do the JamesNow mod. If you don't do the JamesNow mod, I would recomend a 38 pilot jet and 65 pilot air screw (from Sudco, it replaces the pilot air jet on the back of the carb). Definately get the EKQ and EKP needles. Let us know if you have any other questions, and welcome to Thumper Talk. :)

Oh yea, Wicked has been a huge help also!

ColoradoTim,

If your mixture screw(I think that's what you mean) is all the way in, you need to goto a one size smaller pilot jet. The pilot you are running is too rich if it's in all the way.

Curt

colerado tim

you need to cut some more slack in those throttle cables. next go out and do some snap wheelie tests by turning the pilot screw in or out.

if your PS is 1 turn out from all in you need a richer mixture here. if it's 2 or over you need a leaner mixture. if for arguments sake you have the correct needle straight diameter (the third suffix on your needle) then you must change the PAS and PJ to work together.

so a 38PJ needs a #60 PAS setting and a #40PJ needs a #75 PAS setting. then try your snap wheelie taests again and now, at last you should be on the 1.5 turns we all so desire!

Taffy

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