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2008 YZ250 8000-10,000 feet??

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Buddy bought an 08' YZ250 smoker. His stock jetting is so far off the bike barely runs.

Colorado riding. 8000-10,000 feet.

Where should this bike be on jetting?

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Get rid of that 50 pilot right away, there should be a 48 in the bag of goodies that comes with it, that should make a big difference, don't forget to readjust the airscrew. Being that high you're gonna want to lean her down a ways, might not be a bad idea to pickup a 45 pilot also, if that has the N3EW needle it is richer than the N3EJ that came on my 06 to help eliminate the ping you could try raiseing the clip 1 position on the N3EW and if you need more adjusting you'll need to swap needles, get rid of the 178 main and try the 175 then 172

Also modifing the squish band could be something of interest for you, do a search in the Yamaha 2 stroke forum

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Buddy bought an 08' YZ250 smoker. His stock jetting is so far off the bike barely runs.

Colorado riding. 8000-10,000 feet.

Where should this bike be on jetting?

Chazmanian,

A 9000’ average elevation is going to require a much leaner jetting setting vs. stock. I posted a chart below that will help to steer you and your buddy in the right direction. I agree with yathump and think you will find the N3EJ needle a better fit for your high elevation needs. For 70 degrees @ 9000” I would start with a 162 main, 45 pilot, and the N3EJ needle with the clip in the #1 (top) position. Set the airscrew at 1 turn out from fully seated and you will be within a ¼ turn + or – of the ideal setting.

2003-08YZ250Jetting.jpg

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