As altitude increases, the amount of oxygen in the atmosphere decreases by approximately 3 percent for every 1000 feet in elevation. The factory installed carburetor jets perform best at altitudes below 2000 feet. Above 2000 feet, the fuel-to-air mixture becomes too rich. High altitude jets provide the right mixture of gasoline and air.
The 420cc high altitude carburetor kit for the P9500df includes four sets of jets and seals.