YZ426F high altitude jetting

2 replies to this topic
  • dukeyaz

Posted June 03, 2009 - 12:00 PM


Headed to Dillon Colorado from June 11th to 24th and would like information on what size jets I should potentially be using.
If anyone can help that would be great.
Not sure what Jets are in it currently,:eek: guess I better check that tonight for a starting point.
Also if anyone lives around there and has any :crazy: plans, I would love to invite myself along.
2001 YZ426F White Brothers exhaust.

I have not checked on here much so please show me some patience

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  • jimmydoorlocks

Posted June 03, 2009 - 02:13 PM


I'm going to be of little help here.
I live in Denver (a full 4000 ft lower than Dillon) and am running a 2000 426 that I'm also trying to get the jetting worked out on. My jetting is stock (except for I have the external fuel screw now) and the biggest problem I run into is that the main is rich when I'm WFO. Depending on what your jetting is now, where you run the bike now (there are some high altitude, dry places in Arizona too), and how you feel about jetting, there are about an infinite amount of ways you could set it up.
Your best bet is to see what you're working with, then read the stickys (jetting database) at the top of the page. You can also go to the intake page in the technical forums section. The guys and gals on here are great and there is a ton of info that's already been posted, you just have to know where to look. :crazy:
I'd be interested to see what you end up going with and how it works out. Please keep us posted and add what you find out to the jetting database. Have fun in Colorful Colorado!! :eek:

  • shawnbo

Posted June 03, 2009 - 02:27 PM


I live in Castle Rock. I ride at 5000+ feet.

Main Jet: 162
Pilot Jet: 42 (stock)
Starter Jet: 72 (stock)
Leak Jet (if any): N/A
Fuel screw/Setting: 2 turns out
Needle/Position: JD blue needle/4th ring
Mods: Pro Circuit full exhuast

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