High Altitude (Colorado) 01’ 426 Question

2 replies to this topic
  • Bkew

Posted May 01, 2009 - 08:35 PM


First I have been a way a LONG time from this site(6-7 years) and it is nice to be back.
I did peek in now and then though just to see what is going on.

I bought my 01’ YZ426 new (only owner and yes back in 01’) and would never let it go. Back problems made it so I could not ride. I always figured I would get the chance to ride it again, and I think I am there! :smirk:

All giddy with the chance to ride again I did a lot of reading on TT and purchased a R&D Power Pump, Flexjet, and JD Jetting Kit to fix that damn spark plug eating carb. Pro Circuit T4 Exhaust I had previous. I foused on cleaning the carb and much to my surprise the bike fired up on the 3rd-4th kick..!!! *lucky I stored it right.

The question I have is for any Colorado riders or high altitude riders that have the JD JET kit. I have it installed as James recommends.

RED needle 5th clip from the top with a 165 main jet. This is supposed to be a good setup for 6000-9000ft range. The Initial ride tells me it is lean. Right now it is very very cool out so I know it may get better when it is 70-90 degrees out and the air thins more.

But it got me wondering, does the design of the JD jet kit take into account air temperature?? I ask because I am wondering if I should go with the 168 Main and BLUE needle 3rd clip from the top. This is supposed to be a 3000-6000ft range setup and this may be a little closer to what we ride. Rampart is a little higher I think but most the tracks and Pueblo is around 4000-5000 feet give or take.

Just looking for some experience with the kit. I should also note that all the products are top quality and quality people to work with.

Thank in advance for any help, and it is great to be back. :excuseme:

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  • grayracer513

Posted May 02, 2009 - 07:11 AM


Try the blue needle and see.

As to temperature, it takes about a two percent change to correct for 15 ℉, or 4% for 35 ℉. Altitude is roughly 1%/1000 ft.

  • Bkew

Posted May 04, 2009 - 05:13 AM


Thanks Gray. I did place the blue needle in this weekend. Only got a quick test ride as it rained all Saturday. Sunday was nice but a lot of mud so I will have to wait a bit for further testing.

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