99 YZ400 JETTING W/ Big Gun Exhaust

4 replies to this topic
  • YZ400Stefan

Posted April 18, 2006 - 03:41 AM


Can anyone tell me what MAIN jet and what PILOT jet to use with this BIG GUN Race Exhaust setup?

  • robg

Posted April 18, 2006 - 06:25 AM


well I run a big gun race on my 2000 wr400 the pilot is a 48 and the main is 180. Hope it helps Oh yea stock needle jet.

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  • robg

Posted April 18, 2006 - 06:26 AM


I've been between 180 and 185 on the main

  • YZ400Stefan

Posted April 19, 2006 - 04:39 AM


Thanks I'll give it a try...Can I change it without taking the CARB out?

  • viking_in_wa

Posted April 19, 2006 - 07:54 AM


I changed it on my 426 without removing the carb. i just loostened the unit and removed my throttle cables and spun it sideways. got good enough access to it that way. i dont know the real diff between the 400 and 426 jetting but i too have a big gun exhaust and I run a 42 and 165 with a little tweek on the fuel screw.

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