Cleaning The Air Filter - Stihl SP 451 Instruction Manual

English

Cleaning the Air Filter

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3
2
Dirty air filters reduce engine power,
increase fuel consumption and make
starting more difficult.
If there is a noticeable loss of engine
power
N Turn the choke knob to g
N Loosen the screw (1).
N Remove the filter cover (2).
N Clean away loose dirt from around
the filter and inside the filter cover.
N Remove and check the filter
element (3) – replace if dirty or
damaged.
N
Install the filter element in the filter
cover.
N Fit the filter cover.
16
Adjusting the Carburetor
The carburetor comes from the factory
with a standard setting.
This setting provides an optimum fuel-air
mixture under most operating
conditions.
With this carburetor it is only possible to
adjust the high speed and low speed
screws within fine limits.
Adjustments may be performed
only when the machine is
completely and securely
assembled.
Standard Setting
N Stopping the Engine
N
Check the air filter and replace it if
necessary.
N Check that the throttle cable is
properly adjusted – readjust if
necessary – see chapter on
"Adjusting the Throttle Cable".
N Turn the high speed screw (H)
counterclockwise as far as stop (no
more than 3/4 turn).
N Turn the low speed screw (L)
carefully clockwise as far as stop,
then turn it back 1 full turn.
N
Start and warm up the engine if
necessary.
N Adjust idle speed with the idle speed
screw (LA) so that the hook does
not move.
Fine Tuning
A slight correction of the setting of the
high speed screw (H) may be necessary
if engine power is not satisfactory when
operating at high altitude or at sea level.
SP 451, SP 481