01 yz426 main jet size

3 replies to this topic
  • XRrider62

Posted October 13, 2007 - 04:36 PM


Can someone tell me the main jet size for a 2001 yz 426(stock)

  • maxtherat

Posted October 13, 2007 - 09:58 PM


Pretty sure it's a 165 but you may want to go to 168 or a170 depending on your elevation.

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  • Racer808

Posted October 14, 2007 - 05:56 AM


I am in Colorado as well and on my 426 we left the main alone and went from a 42 pilot to a 40 and it did wonders!! Then my mechanic friend did all sorts of tuning to the screws on the carb and the bike ripped, I loved the engine on that bike, I just hated how it felt like a battle tank. Also, Dr D pipe really made that bike complete.

  • klxnewguy

Posted October 14, 2007 - 02:50 PM


I have all stock jetting, but I just put on an WB E2 pipe due to the greenies wanting my bike below 96db and I took it out on a ride yesterday and something was off. The bike would start fine, start going but from 1/4 - 1/2 throttle the bike wouldn't pick up much. It just bogged and then if I opened it all the way up it would clear and get going but as soon as I would want just a good steady pull up a hill around 1/2 throttle it would bog again. It was also up a bit in altitude. Any help would be great, thanks!!

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