Abstract: The invention is directed to a membrane carburetor for changing the air/fuel ratio. The membrane carburetor achieves the same result as previous carburetors but at a greater insensitivity to wear and disturbances as well as an improved controllability in a constructively simpler and more compact manner. The carburetor includes a coil arranged about a valve needle so that the coil and the valve needle conjointly define a solenoid actuator. The valve needle is the armature of the solenoid actuator. When a limit rpm is reached, the coil is activated by a current and the armature is raised and thereby a greater flow of fuel is made possible. The enrichment of the air/fuel mixture achieved in this manner limits the engine rpm. The membrane carburetor wherein the air/fuel ratio can be changed is for an internal combustion engine of a portable handheld apparatus such as a motor-driven chain saw, hedge clippers and the like.

Abstract: Method and apparatus for cooling the cylinder head of an engine of the type in which oil is delivered to the area located above the combustion chambers in the cylinder head and the latter is cooled by thus delivered oil. Oil introducing means through which oil is introduced into the area located above the combustion chambers in the cylinder head are disposed in the vicinity of ignition plug fitting bosses on the cylinder head whereby oil pumped up from the oil supplying device is delivered to the area located above the combustion chambers in the cylinder head through the oil introducing means.