A diaphragm carburetor having a carburetor casing defining a mixing passage. A measuring chamber is disposed in the carburetor casing and is partitioned into a fuel chamber and a compensation chamber separated by a control diaphragm. The compensating chamber is closed to the surrounding atmosphere but is connected to a channel. An opening of the channel enters into a space between the air filter and a fuel inlet in the mixing passage. The channel is at least partially defined by a pipe extending through the carburetor casing. The pipe is adapted for assembly/disassembly from outside of the casing. The pipe is attached to a spacer for properly orienting and fixing the pipe relative to the casing during assembly.