Carburettor - Pressure Testing - Husqvarna 455 Rancher Workshop Manual

Carburettor
8
Fit the air shutter blade on the shaft (L) and con-
nect the throttle actuator rod (N) in parallel with the
ordinary throttle valve. The valve housing (P) is
secured in the carburettor using two screws.
L
N
A
9
Carry out a pressure test.
Pressure testing
Pressure testing should be carried out with the car-
burettor fully assembled. Testing should always be
carried out after the carburettor has been repaired,
but it can also be carried out as trouble shooting
before dismantling the carburettor.
See fi gure below and carry out the test as follows:
1
Unscrew the high and low speed screws one turn
from closed position.
2
Connect pressure tester to the carburettor's fuel
intake.
3
Lower the carburettor into a beaker of water.
4
Pump the pressure up to 50 kPa (0.5 bar).
5
No leakage is permitted. If a leakage occurs refer
to the table below.
Leakage at
Diffuser jets
Leakage in impulse tube
Ventilation hole
on metering unit.
14
– English
A
A
P
A
Fault with
Needle valve
Pump diaphragm
Control diaphragm
Carburettor – refi tting
NOTE!
Cleanliness is very important when reas-
sembling the carburettor. Tiny particles of
dirt can cause operating problems.
1
Position the carburettor in the carburettor compart-
ment. Fit the carburettor in the rubber mountings (B).
P
B
2
Tighten the carburettor screws (x4,C) with a torque
of 1-1.5 Nm. Fit the fuel hoses (x2,D). Fit the
throttle actuator rod and press down its lock.
C
C
3
Connect the leads to the stop switch and the short
curcuit spring. Fit the air fi lter and cylinder cover.
B
D
C
D
C