CARBURETTOR
GB Carburettor
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WARNING! The fuel that is used in the chainsaw poses the following hazards: 1. The fluid and its fumes are poisonous. 2. Can cause skin irritation. 3. Is highly inflammable.
Description The diagrams with this description do not show the actual carburettor on the chainsaw. They serve only to illustrate the principles of arrangement and function. Arrangement The carburettor comprises three sub-systems: • • •
Metering unit, A in fig. 1. Mixing venturi, B in fig 2. Pump unit, C in fig. 3.
The metering unit (A) contains the jets and fuel control function. It is here that the correct amount of fuel for the given engine speed and power demand is metered.
Fig. 1
A
Fig. 2
B
Fig. 3
C
In the mixing venturi (B), the choke, throttle butterfly valve and diffuser jets are located. Air is mixed with the fuel to give a fuel/air mixture that can be ignited by the ignition spark.
In the pump unit (C), fuel is pumped from the fuel tank to the metering unit. One side of the pump diaphragm is connected to the crankcase and pulses in time with the pressure changes in the crankcase. The other side of the diaphragm pumps the fuel.
26 – English
