In an example of the classical approach, the narrator explains that one must pay continual attention: when the narrator and his friends came into Miles City, Montana he notices that the "engine idle is loping a little", a possible indication that the fuel/air mixture is too rich. The next day he is thinking of this as he is going through his ritual to adjust the jets on his motorcycle's carburetor. During the adjustment, he notes that both spark plugs are black, confirming a rich mixture. He recognizes that the higher elevation is causing the engine to run rich. The narrator rectifies this by installing new jets with the valves adjusted, and the engine runs well again.