Cross-County trip - Dealing with Elevation Changes
 

I have been posting quite a few questions lately, as I am setting up my wife's bike for our TAT West trip this summer. This question is specifically dealing with altitude and overall bike performance. So... We are leaving from Texas and headed all the way to the Pacific Ocean in Port Orford Oregon. Basically the trip will be from sea level to 12,000 feet or so and back down. The bike (2006 KLX250S) is all stock with standard jetting. I would more or less like to leave it that way. My wife does not do wheelies, however, she will need to top the hill. I have gone ahead and order a “t-handle” kouba fuel screw, as I see that being useful in fine tuning fuel mixture. Other than that, do you all think anything else is actually necessary? I can always take the air box lid off in higher elevations if need be.

Simply taking the air box lid off worked for me on my stock KLX when I went from 750' in IL to 11,000' in CO. It wasn't perfect, (bogged some at wide open throttle) but it was close. I had jets with me on that trip, but the lid off worked so I went with it.
Have fun, take pictures , and post a few up here.
Dan

jglow, if your wife is happy with that bike the way it's jetted from the factory, I can't help but believe it might even get better with a little altitude. The bike is horribly lean as delivered. Some richness induced by altitude might actually help.

That said, I think many overanalyze the performance of these bikes at altitude and usually think a rejet toward the leaner end of the spectrum is an absolute requirement. I've had many bikes here in Texas that I've taken all over the western U.S., and I've yet to have to rejet them in Colorado or other high places. I live at about 1700' and have my jetting set spot-on with a DJ kit and other mods. I think if you have optimum jetting at your home altitude, these CV carb bikes will do just fine at high altitude. Many have the impression that they will be constantly way above 10,000', and that's just not the case, even if you stay in just Colorado alone. Even if you're a tiny bit rich at 12,000', you won't be there long, and the bike would probably suck for the majority of the time you were at lower altitudes. My KLR600/650's and this KLX with CV carbs have performed better than cable pull slide carbed bikes every time while operating at altitude extremes. Especially since your wife's bike still has the extremely lean stock jetting, I'm almost positive you won't have an issue. And of course as Dan suggested, you can remove the airbox lid under the worst case scenario.

Thanks guys. That's what I was hoping to hear. My wife is very content with chugging (lugging) around on the bike in it's current condition, so we should be in good shape. I will be on a wr250r so this will be a really good side by side performance comparison of the two. The plan is to leave mid-late June, and I think we will try to keep a live blog (as live as possible at least) like we did we the Alaska trip last summer. I just checked the valves (all perfect and in middle of range with 3600 miles), and started running wires for 12v power and headlight kill switch. Just about ready to start some shake down rides.