426 Jetting Specs

2 replies to this topic
  • Jeepentj

Posted February 20, 2001 - 02:07 PM


I noticed that I am not the only person from Arizona here. Do any of my fellow Phoenicians have a 2001 YZ426? If so, have you deviated at all from the factory jetting? If so, what have you changed and what have you changed it to? Thanks for the information.

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  • motoman393

Posted February 20, 2001 - 02:39 PM


I changed my jetting on a 01' YZ426 to a 48 pilot and 168 main and it ran like crap...after many hours of messing with the jetting and trying many combos the stock jetting works the best but turn the fuel screw out to 2 1/2 turns and mine runs and starts great! The 01' seems to need diff. jetting specs than the 00' model! I also have a WB R4 exhaust and the jetting works perfect with it also!


I get my kicks on a 2001' YZ426!
Friendswood, TX

  • F-Pilot

Posted February 20, 2001 - 07:08 PM


I am here in Az and ride an '00 426 with a WB Pro-Meg exhaust, Uni or Twin-air filters with the screen removed (have never had any of my YZF's backfire) and an 8oz flywheel weight.
I have tried some jetting changes with the main and pilot and found the stock 162 main to be best but have swapped the stock 42 pilot for a 45 (probably due to WB pipe)
I have not messed with the needle clip position because the bike seem to pull really hard through the middle and the plug looks good.
I may drop the main to a 160 or drop the needle when summer(90+) gets here :)

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