Carburettor - Husqvarna 555 Workshop Manual

Repair nstructions

7.14 Carburettor

WARNING!
The fuel used in the chain saw has
the following hazardous properties:
1. The fluid and its vapour are
poisonous.
2. Can cause skin irritation.
3. Is highly inflammable.
Description
The gures accompanying this description do not
correspond with the carburettor on the chain saw.
They show only the principle of design and func-
tion.
Design
The carburettor is based on three sub-systems:
Metering unit, A.
Mi ing unit, .
Pump unit, C.
The needles and the fuel s control functions are
located in the metering unit, A. Here the correct
quantity of fuel is ad usted for the actual speed and
power output. See gure 27.
The mi ing unit houses the choke, the throttle
al e and the diffuser ets. Here air is mi ed with
the fuel to gi e a fuel/air mi ture that can be ignited
by the ignition spark. See gure 28.
n the pump unit C, fuel is pumped from the fuel
tank to the carburettor s metering unit.
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. See gure 29.
34
- English
ig 27
ig 28
ne side of
ig 29
B