Stihl 064 - Page 77

STIHL 064, 066 77
11.2 Construction and
Operation of Carburetor
with Compensator
Carburetor with compensator
Carburetor without compensator Pi = Internal pressure
Pi = Internal pressure Pa = Atmospheric pressure
Pa = Atmospheric pressure Pr = Pressure in metering chamber
Pr = Pressure in metering chamber 1 = Compensator
1 = Box-type filter 2 = Box-type filter
The compensator carburetor A sleeve is fitted between the end The mixture cannot become over-
keeps the fuel content in the cover and air filter. rich. And it is no longer necessary
mixture constant at all times, to alter the setting of the high
irrespective of how dirty the air The air volume is reduced when speed adjusting screw as contami-
filter is. The pressures at the the air filter is dirty. This not only nation of the air filter increases.
clean air side of the air filter increases the depression in the However, engine performance
and the metering diaphragm are carburetor's venturi, but also de- drops due to the reduction in air
always equal. creases the pressure applied to volume and can only be restored
the outside of the metering dia- to normal by cleaning the air filter.
The end cover of the new carbure- phragm. The metering diaphragm
tor, the rear half of the air filter moves upward, causing the
each have an integrally molded needle valve to close part-way and
connector. thus reduce the supply of fuel.