Will altitude affect jetting that much?

[jasonsb]

I'm from Los Angeles (sea level) and I want to tune my bike for Glamis. I tried running on the street but I can't really punch it like I want to. The only place I can do test runs is about 60 miles away. The problem is that the elevation is way higher than sea level. Could I dial it in at a higher elevation and run it at Glamis without having serious problems. I mainly want to dial in the pilots, air screws, and needle.

[sredish]

Altitude definitely affects jetting. If you take a bike jetted for sea level and take it to 3,000 feet, you could be fouling plugs cause your too rich. The rule of thumb I use is, 10% jetting change on the main per 1,000'. And adjust the pilot to idle properly. If you jet it for well above sea level, when you go back to sea level, you'll have leaned out and that can be dangerous so be careful.