This negative pressure type carburetor has the capacity to provide smooth fuel supply even at times when there is a discrepancy between engine rpm and throttle opening, such as on uphills, where the engine rpm is low but the throttle opening is large, or on downhills, where the negative intake pressure is large but the throttle opening is small. The key feature that contributes to outstanding engine response on the FZ16 is the TPS (Throttle Position Sensor) on the carburetor. This sensor makes possible 3-dimensional control of ignition timing advance by means of “3-dimensional mapped advance control” based on engine rpm and throttle opening. This provides a higher level of drivability and contributes to excellent fuel economy.