GB-11
G
B
Fig. 3-1
Fig. 3-3
Fig. 3-2
MAINTENANCE, REPLACEMENT, OR RE-
PAIR OF THE EMISSION CONTROL DE-
VICES AND SYSTEM MAY BE
PERFORMED BY ANY NON-ROAD ENGINE
REPAIR ESTABLISHMENT OR
INDIVIDUAL.
Carburetor adjustment (Fig. 3-1)
WARNING!
Never start the engine without the complete
clutch cover. Otherwise the clutch can
come loose and cause personal injuries.
In the carburetor, fuel is mixed with air. When
the engine is test run at the factory, the
carburetor is adjusted. A further adjustment
may be required, according to climate and
altitude. The carburetor has one adjustment
possibility:
T = Idle speed adjustment screw.
Idle speed adjustment (T)
Check that the air filter is clean. When the idle
speed is correct, the cutting attachment will not
rotate. If adjustment is required, close (clock-
wise) the T-screw, with the engine running,
until the cutting attachment starts to rotate.
Open (counter-clockwise) the screw until the
cutting attachment stops. You have reached
the correct idle speed when the engine runs
smoothly in all positions well below the rpm
when the cutting attachment starts to rotate.
If the cutting attachment still rotates after idle
speed adjustment, contact HITACHI dealer.
WARNING!
When the engine is idling the cutting
attachment must under no circumstances
rotate.
5. Maintenance
NOTE!
Some models sold areas with strict exhaust
emission regulation do not have high and low
speed carburetor adjustments. Such
adjustments may allow the engine to be
operated outside of their emission compliance
limits. For these models, the only carburetor
adjustment is idle speed.
For models that equipped with low and high
speed adjustments; carburetors are pre set at
the factory Minor adjustments may optimize
performance based on climate, altitude, etc.
Never turn the adjustment screws in increments
greater than 90 degrees, as engine damage
can result from incorrect adjustment If you are
not familiar with type of adjustment-assistance
HITACHI dealer.
Air filter (Fig. 3-2)
The air filter (1) must be cleaned from dust and
dirt in order to avoid:
Carburetor malfunctions.
Starting problems.
Engine power reduction.
Unnecessary wear on the engine parts.
Abnormal fuel consumption.
Clean the air filter daily or more often if working
in exceptionally dusty areas.
Cleaning the air filter
Remove the air filter cover (2) and the filter (1).
Rinse them in warm soap suds. Check that the
filter is dry before reassembly. An air filter that
has been used for some time cannot be
cleaned completely. Therefore, it must regularly
be replaced with a new one. A damaged filter
must always be replaced.
Spark plug (Fig. 3-3)
The spark plug condition is influenced by:
An incorrect carburetor setting.
Wrong fuel mixture (too much oil in the
gasoline)
A dirty air filter.
Hard running conditions (such as cold
weather).
These factors cause deposits on the spark
plug electrodes, which may result in malfunc-
tion and starting difficulties. If the engine is
low on power. difficult to start or runs poorly at
idling speed, always check the spark plug first.
If the spark plug is dirty, clean it and check the
electrode gap. Readjust if necessary. The
correct gap is 0.6 mm (.024
″
). The spark plug
should be replaced after about 100 operation
hours or earlier if the electrodes are badly
eroded.
NOTE!
In some areas, local law requires using a
resistor spark plug to suppress ignition signals.
If this machine was originally equipped with
resistor spark plug, use same type of spark
plug for replacement.
