I am looking at buying a Yamaha Grizzly 660, but I was told that if I take it up in the mountains, I will have to have the carb rejetted. I live in Albuquerque, NM which is at about 5300 ft above sea level. Santa Fe is at about 7000 ft, and the mountains where I like to go play are at about 8000-9000 feet. If I buy a quad in Albuquerque or Santa Fe, will I have to have it rejetted to go in the mountains? How high and how low in elevation can I go before I need to have it rejetted?

 

When you decide to buy, the dealer should ask you where you plan on doing most of the driving. They should be able to do the high altitude jetting for you. Basicly its a smaller main jet, and 1/4 turn in, on the mixture screw. CV carbs are somewhat self adjusting in the midrange, so the needle doesnt get played with.
If you have it jetted for the high altitude, itll be too lean , when you get back to lower elevations. That could be a problem, especially if you like using the main circuit (WOT), or riding in cold weather, which just makes it leaner.
You could ask for their advice, they may know how many holes to put in the lid, for when your at high alts, which will lean it out, and then just recover those holes for lower elevations, and then you could get by with stock jetting. The solution may be as simple, as totally removing the lid, when the motor starts to run like its loading up, when you get to the higher elevations.

Ask the dealer, you arent the first or only guy to ask, and theyll help you. You may have to ask the service advisor, most salesmen dont know about carbs.