English / USA
Adjusting the Carburetor
H
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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 screw within fine
limits.
24
Standard Setting
:
Shut off the engine.
:
Mount the cutting blade and clean it
if necessary (make sure it is not
L
1
damaged or warped).
:
Check adjustment of the throttle
cable* and readjust if necessary –
see "Adjusting the Throttle Cable".
:
Check spark arresting screen* and
clean or replace if necessary
:
Check the air filter and replace if
necessary.
LA
:
Turn high speed screw (H)
counterclockwise (max. 3/4 turn)
as far as stop.
:
Carefully screw the low speed
screw (L) down onto its seat. Then
open it one turn counterclockwise.
:
Start and warm up the engine.
:
Adjust idle speed with the idle speed
screw (LA) so that the cutting blade
does not rotate.
*
see "Guide to Using this Manual"
Fine Tuning for Operation
at High Altitudes
A slight correction of the setting of the
high speed screw (H) may be necessary
if engine power is not satisfactory.
Rule of thumb
:
Turn high speed screw (H) about
a quarter turn for every 3300 ft
(1000m) change in altitude.
:
Carry out standard setting.
:
Warm up the engine for about 5
minutes.
:
Open the throttle wide.
:
Turn high speed screw (H) clock-
wise (leaner) no further than stop
until there is no noticeable increase
in engine speed.
It is possible that maximum engine
speed may be reached with the
standard setting.
FC 75