Induction system of internal combustion engine

Claim 1

An induction system of an internal combustion engine comprising cylinders each having at least one exhaust port and two inlet ports, an exhaust valve controlling said exhaust port, a first inlet valve controlling a first one of said inlet ports, a second inlet valve controlling the second of said inlet ports, carburetor means for supplying a fuel-air mixture for said engine, a first induction passage leading from said carburetor means to said first inlet port for supplying fuel-air mixture to said first inlet port controlled by said first inlet valve, a second induction passage leading from said carburetor means to said second inlet port for supplying fuel-air mixture to said second inlet port controlled by said second inlet valve, a first throttle valve controlling flow of fuel-air mixture in said first induction passage, manually operable means for controlling said first throttle valve, a second throttle valve controlling flow of fuel-air mixture in said second induction passage, diaphragm means responsive to suction in said first induction passage controlling said second throttle means, a first cam actuating said first inlet valve, said cam having a contour to produce valve movement to provide high torque at low engine speeds and to maintain said first inlet valve closed when said exhaust valve is open, and a second cam actuating said second inlet valve, said second cam having a contour which is different from that of said first cam and which produces movement of said second inlet valve to provide high power at high speeds.