Husqvarna 455 Rancher II Workshop Manual page 36

Repair Instructions
Function
The carburetor operates differently in the following
modes:
• Cold start mode
• Idling mode
• Part throttle mode
• Full throttle mode
In cold start mode the choke valve H is completely
shut. This increases the vacuum in the carburetor
and fuel is easier to suck from all the diffuser jets
D, E, and F. The throttle valve I is partly open. The
throttle valve, J, is closed. See figure 30
In idling mode, the throttle valves I and J are
closed and the choke valve H is open.
Air is sucked in through an aperture in the throttle
valve and a small amount of fuel is supplied
through the diffuser jet D. See figure 31.
In part throttle mode, the throttle valve I is partly
open and the choke valve H is fully open. Fuel is
supplied through jets D and E. The throttle valve J
starts to open. See figure 32.
In the full throttle mode both valves are open and
fuel is supplied through all four diffuser jets (D, E, F
and G). The throttle valve J is also fully open. See
figure 33.
36 –
English
Fig 30
Fig 31
Fig 32
Fig 33