YZ125 at 3000ft

Anyone have a stockish 05+ 125 running clean at this elevation? If so whats your jetting/premix specs?


Your pre-mix should be between 32 and 40:1. Yamaha recommends 32:1.

High altitude causes bikes to run rich. The air is thinner and there is less oxygen. You are most certainly going to want to use smaller jets. Check out this link for altitude jetting predictions:


Thanks for the chart, thats perfect!

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