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I have a 2007 Can am Outlander 400 Max. I live in Phoenix, AZ with an elevation of 1200 ft. I am going to Ouray CO for several days to ride in elevations ranging from 8000 to 13000 ft. Is it a must to re-jet the carb? I would prefer not to, but I don't want to get there and find out the my ATV won't run. I have a Mikuni BSR33 carb with a main jet size of 133.7. What should I do?
My typical mountain ride starts in the valley at about 4,000', and can go up to nearly 12,000'....all in one day's ride! I also have places where I ride that are below sea level, so I have kept stock jetting. You can rejet by decreasing the fuel, or by increasing the air.....
On a carburated quad, I install as many Thunder Products TPI Valves as I can in the airbox lid (from the same folks who make the Dial-a-Jet by the way). As I ascend, I open them up gradually for more air intake. As I descend, I close them gradually so I won't be running lean (lean can damage an engine!). Above about 9,000" I just pull the airbox lid off completely. This is a system that works very well! It's the easy solution for those of us who ride big altitude changes....and costs almost nothing.