high altitude jetting

I'm currently running 48/165 on my '08. Most of my riding is sea level to around 3000 ft, and it works great.

However in a couple weeks I'll be going on vacation, and spending a week riding anywhere from 6000 to 8000 ft, very low humidity, temps in the 80s.

I'm thinking of going maybe to 45/160 or a 162 main.

Any thoughts? :thumbsup:

45/160, may even need to go as low as 38/145. You should also bring a few extra needles in thicker diameters to lean out everything in between idle and WOT.

Take a look at the Merge Racing site. They have a RAD (Relative Air Density) jetting calculator. You enter in current jetting, weather data and the chart then tells you what jetting is needed for other conditions.


Without considering anything but the change in altitude, the formula I have suggests 158/45.

The merge calculator looks good. Quite a few steps to get to it all, but very thorough. I'll have to fiddle with it some.

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