To improve quality of exhaust gas and to attain low fuel consumption in a four cycle engine in which an intake passage having two intake valves 8 and 9 and two intake ports is provided per cylinder 3, the intake ports are branched from a common intake pipe 13, each of the intake ports is guided to upper sides of the intake valves 8 and 9, one of the two intake ports is constituted as a charge loading port 11 and the other is constituted as a volume port 12, a throttle device 21 for intake amount control is interposed in the intake passage and the intake passage is connected with a fuel supplying device.
This fuel supplying device is constituted of a joint carburetor 14 for both intake ports of a charge loading port and a volume port. The carburetor 14 is characterized by disposing both the intake ports in an area branched from the intake pipe 13.
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