Abstract: To provide a mechanism for coordinating the operation of throttle valves in a carburetor system in which a plurality of carburetors are connected in series and are then arranged in parallel with one another so as to position shafts thereof in parallel with one another. The throttle valves are rotated on said shafts to open or close passages of the carburetors. In the throttle valve operation coordinating mechanism, each of the carburetors connected in series shares one shaft which is received in bearings positioned at opposite ends thereof. A link extends between the shafts of the carburetors arranged in parallel and coordinates the operation of the shafts.

Abstract: A multi-cylinder internal combustion engine is mounted on the frame body of a motorcycle. The engine has a front cylinder block extending forward and a rear cylinder block extending upward so that a V-shaped space is defined between the cylinder blocks. A downdraft carburetor supplies fuel to the front cylinder block and a lateral-draft carburetor supplies fuel to the rear cylinder block. Both carburetors are positioned in the V-shaped space and their air intake ports are in close proximity but offset laterally. The intake pipes to the carburetors have essentially the same length and geometrical arrangement. First and second exhaust systems for the two cylinder blocks are essentially the same length although the exhaust system for the front cylinder block extends under the engine to one side of the rear wheel of the motorcycle and the other exhaust system for the rear cylinder block extends at a higher elevation to the other side of the wheel.

Abstract: A carburetion system for V-type internal combustion engine having a first carburetor and a second carburetor disposed in a space between a first cylinder and a second cylinder arranged in a form like V and adapted to supply air-fuel mixture to respective cylinders independently, improved to have a compact structure and superior intake charging efficiency with capability of substantially uniformly supplying the mixture during acceleration and deceleration of the vehicle. The carburetors have intake barrels defining therein intake passages communicating with the associated cylinders. The intake barrels are disposed substantially at right angles to the axes of the associated cylinders and in the close proximity of each other in such a manner as to partially cross each other. A pair of float chambers are disposed between the intake barrels below the point of crossing of the intake barrels.

Abstract: An improved carburetion system for a V-type internal combustion engine including a first carburetor and a second carburetor disposed in a space between a first cylinder and a second cylinder arranged in the form of V-shape and adapted to supply an air-fuel mixture to the respective cylinders. The respective carburetors each includes an intake barrel and a float chamber in which fuel to be supplied to said intake barrel is stored, said intake barrel having an inlet port and an outlet port and defining an intake passage leading to the associated cylinder. The intake barrels of both the carburetors are arranged in the ultimate proximity of one another in such a manner that they intersect one another and a point of intersection of the intake barrels is offset from the middle part of the intake barrels toward the inlet port of the latter. Thus, the respective float chambers are located in a space between both the intake barrels below the point of intersection.

Abstract: A variable venturi type carburetor for motor cycle and the like which is constructed with a carburetor main body, an air intake passageway formed in the carburetor main body, a piston type throttle valve provided in the air intake passageway and which also serves as a variable venturi, a pressure receiving part provided on the upper part of the throttle valve and having a function of opening the throttle valve upon its receipt thereinto of an intake negative pressure of the engine, a control lever for the throttle valve opening and closing which is supported on the rotational shaft within the pressure receiving part and restricts the throttle valve to a predetermined degree of opening by closing and opening of the valve in association with the throttle valve operation, and compulsory valve opening device interposed between the throttle valve and the throttle valve operating and interlocking system, the compulsory valve opening device following movement of the control lever for opening and closing the throttle