I bought my GL1100i in 12/06. 7/07 the wife and I set out for New Mexico from INDIANA! I set my altimeter at the Continental Divide at 7,400 ft altitude. Anytime we were over 4,000 ft the bike would run rough, at times. Not always. The carbs were adjusted and set in Indiana at 500 ft. Above 4,000 ft the air was thinner (less oxygen). The bike ran rich (too much gas for the amount of oxygen) and coughed and sputtered. The solution ... down shift and wait till you are below the elevation where the bike runs smooth. Any carbeurated vehicle will do this. The computer in fuel injected vehicles reset themselves, so no problem. Unless you want to constantly reset your carbs, set your carbs for home and when you go up the mountains just downshift and keep sputtering along until you get back home.