crazyrydermx said:
Higher elevation=less air...therefore, tune your bike accordingly...make it run richer basically
Wrong. He wants to lean it not richen it to correct for the reduced air density at higher elevation.
Higher elevation means less air density, so there is less oxygen in a given volume of air because it isn't packed together as tightly. For increased elevation alone, you need to lean the jets out, which is normally 1 jet size per 1000ft of elevation.
But, if temperature changes as well, you have to account for that as well. If the temperature is lower than what the bike is currently jetted for, you will need to richen the jetting slightly because air gets more dense with lower temperatures, hence more oxygen in a given air volume, and you need more fuel to have the correct air/fuel ratio. If the temperature is warmer, the air is less dense, less oxygen, and you need to lean the jetting out to deliver less fuel.
If the bike is jetted correctly, it is normally 1 jet size for a temperature change of 20 degreesF plus or minus from your baseline temp the jetting is set for.
As you can see, you have to know what the changes are for both temperature and elevation. If temperature decreases and elevation increases, depending upon the magnitude of each change, you may or may not even have to alter the jetting.
Mikuni makes a very handy slide rule jetting calculator, that allows you to do these elevation and temperature corrections very quickly. You simply correct it for your elevation change from your current jetting, and then for the temperature change, just as you would do when calculating it by hand.