I live at 7200' elevation. I seldom get below 5000' with the KLR. So, since I bought it a couple of months ago, it has run somewhat rich. The dealer tech looked at me like I had 2 heads when I asked him if they put the high elevation jets in before they sold them. He told me it was completely unnecessary, and would be too lean. I ordered the Kowalski jets intended for use above 4000' a few weeks ago on the 'net. They finally arrived yesterday. I took the bike apart immediately, and installed the new little brass gizmos. Stock (For sea level) is 40 primary, 148 main. The new ones are 38 and 145 respectively. I also bought a 142, just in case, but I don't know if I will ever get to use it.
Anyway, it really woke the KiLR up. Much better throttle response, and definitely an improvement on the top end. Should see a sustantial improvement in fuel economy to boot. I have been getting 47 mpg.......Maybe I will get on the high side of 50. And it ought to eliminate the soot accumulation on the rear fender next to the exhaust, too.
So if you are a mountain dweller, you might find it worthwhile to re-jet, in spite of the dealer's opinion.

What happened to the time when you could walk into a bike shop and talk to actual guys/gals that know anything. If it was printed on a brocure or in a training video thay had monday morning then they wouldnt have a clue. I had a couple of screws vibrate loose and fall out of the fairing on my bike a few weeks ago. I went to the service dept and you would have thought that I had asked for the answer to world peace. He looked through books and all over the place. I had to tell him that it didnt matter to me what the screw came from as long as it did the job.. maybe it will be in next weeks video/brocure. lol