Rejetting

Ok... I'll bite ;) Basically, when conditions changes, such as temperature, altitude, and humidity, the density of the air changes, and this therefore alters how much fuel needs to be mixed with the air to create maximum power. A lot of machines will run "ok" in most conditions without jetting changes... but if you want to search for maximum power in all conditions, you need to spend some time jetting. In a high altitiude situation, where the air density is low, you jetting is going to be signifigantly richer than when your at lower altitudes. First of all, its not possible to make as much power at much higher altitudes than it is down near sea level, there just isn't as much air to burn. But you can make the best of what air you have by getting the jetting spot on. Changing your jetting should have a pretty pronouced effect on the power of your machine. To learn some more, here is a link to Eric Gorr's guide on jetting. Check out this whole site, lots of good resources. http://www.ericgorr.com/twostktech/carbtuning.html Have fun, and good luck.

Let me correct, can't edit yet... Your jetting will need to be leaner (Smaller jet sizes) at higher altitudes, because the stock jetting will be to rich... too much fuel.

You can spend a lifetime learning the intracacies of jetting. But the first step is to be sure to understand the definiton of "rich" and "lean". The richer you make something means: You have more gas entering the cylinder. Sound simple enough, YA RIGHT. Start considering adding two stroke oil to the mix. The more oil you add the leaner you make your fuel entering the cylinder. WALA! You have just adjusted you fuel mixture without touching the needle air screw or any jets.

All this really boils down to is, you better get a lot of info together before you start, and study it well and get a good comprehension of the "basics". It's not that deep especially if you like to tinker with your bike. It will pay off tremendously with the self satisfaction of learning to "master" your beast.

By the way you didn't say if it was a two stroke or four stroke. If it is new enough to have throttle position sensor etc. All these thing factor in but still require Jetting to be adjusted.

I hope this is more help then harm.
Jim