Fuel supply system for internal-combustion engine

A fuel supply system for an internal-combustion engine, the fuel supply system comprising:

• fuel supply means;
• an intake-air passage connected through an intake valve to a combustion chamber defined by a cylinder and a piston, said intake-air passage having a volume between the fuel supply means and the intake valve means equal to a volume of the cylinder at a lowest point of a stroke of the piston, wherein the
• fuel supply means is disposed in a portion of said intake-air passage at such a position that the relationship between a volume V.sub.IN of said intake-air passage extending from the fuel supply means to said intake valve and a volume V.sub.COM of said combustion chamber determined at the lowest point of the stroke of the piston satisfies the following condition:
• V.sub.IN =0.7 to 1.2 V.sub.COM
• whereby air present between a vicinity of the intake valve and the fuel supply means is sucked in in accordance with a progress of the intake stroke of the internal combustion engine, with the fuel supplied by the fuel supply means being concentrated at an end of the intake stroke in a vicinity of an ignition plug disposed in an upper part of the cylinder.