port polish / jets

3 replies to this topic
  • drc02

Posted February 18, 2008 - 11:06 PM


I had the head on a 01' 426 port and polished. The carb is stock, no mods or add on's, and fmf power bomb head pipe w/turbin core end. What would be a good starting point for jettting. Ive lookd through a lot of posts cant find much other than jet kit recomendation. I have a zip ty fuel screw and boysen pump cover i will try after i get jet hurdel cleared.

  • William1

Posted February 19, 2008 - 04:28 AM


By only porting, your jetting will barely change, if at all.

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  • 642MX

Posted February 19, 2008 - 05:22 AM


What would be a good starting point for jettting.

How does the bike run?

  • USED YZ426F

Posted February 19, 2008 - 07:54 AM


Porting may help with the flow somewhat, but it shouldn't change the A/F ratio.

If the bike runs fine now (or before the head porting) then you probably won't need to change the jetting.

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