Carburettor; Description; Design - Husqvarna 565 Workshop Manual

Carburettor

WARNING! The fuel used in the
chainsaw has the following
hazardous properties:
1. The fluid and its vapour are
poisonous.
2. Can cause skin irritation.
3. Is highly inflammable.

14.1 Description

The figures accompanying this description do not
correspond with the carburettor on the chainsaw.
They show only the principle of design and
function.

14.2 Design

The carburettor is based on three sub-systems:
• Pump unit.
• Metering unit.
• Mixing unit.
In the pump unit (A), fuel is pumped from the fuel
tank to the carburettor's metering unit. One side
of the pump diaphragm is connected to the crank-
case and pulses in time with the pressure changes
in the crankcase. With the help of inlet and outlet
valve in diaphragm, the fuel is transfered through a
filter screen to inlet needle. See figure 1.
The fuel control unit is attached to the metering
unit (B). Here the correct quantity of fuel is ad-
justed for the actual speed and power output. See
figure 2.
The mixing unit (C) houses the choke, the throttle
valve and the diffuser jets. Here air is mixed with
the fuel to give a fuel/air mixture that can be ignited
by the ignition spark. See figure 3.
32 - English
14 Carburettor
Fig 1
Fig 2
Fig 3
A
B
C