Carburetor Jetting for High Elevations
At high elevation, the carburetor air-fuel mixture will be too rich. Performance will decrease, and fuel consumption will increase. If an engine / product will be used regularly above 5,000 feet (1,500 meters), change the carburetor main jet to improve the performance and exhaust emissions.
There are 2 optional main jets for each engine. For elevations above 5,000 feet but below 8,000 (1,500 to 2,438 meters) use the first smaller jet. For elevations above 8,000 feet, the second smaller jet should be used.