Maintenance; Carburetor Adjustment - Hitachi CM 75EAP Handling Instructions Manual

MAINTENANCE

Carburetor adjustment

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) (Fig. 30)
Check that the pre-fi lter and paper fi lter are clean. When the
idle speed is correct, the cutting attachment will not rotate.
If adjustment is required, close (clockwise) 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 Authorized Service Centers.
WARNING
When the engine is idling, the cutting attachment must
not rotate under any circumstances.
NOTE
○ Please use combi box spanner for adjusting the T-screw.
○ Do not touch the High speed adjustment (H) and the
Low speed adjustment (L) screws on the carburetor.
Those are only for Hitachi Authorized Service Centers.
If you rotate them, it will cause a serious damage to the
machine.
Air fi lter (Fig. 31)
If the engine power seems to have decreased, it is likely
because the air fi lter needs to be cleaned.
1. Before cleaning the air fi lter, pull the choke lever (22) to
prevent dust from entering into the engine.
2. Open cleaner box (B) (32) by loosening cleaner knob
(33) to expose the pre-fi lter (sponge form) (34) inside the
cleaner box (B) (32).
3. Clean the pre-fi lter by tapping or blowing it gently. If the
pre-fi lter is still dirty, rinse it in warm soap suds.
If the inside of cleaner box (B) (32) that is closed off by the
pre-fi lter is dirty with dust, clean the paper-fi lter (35) in the
following manner.
4. In order to take out of paper-fi lter (35) and nylon-fi lter
(36), open the cleaner box (A) (37) by loosening the M5
set bolt (38).
5. Clean the nylon-fi lter by tapping or blowing it gently. If
the nylon-fi lter is still dirty, rinse it in warm soap suds.
6. Clean the paper-fi lter by tapping. If you use compressed
air to blow out the dust, apply the air gently from inside.
7. Reassemble the parts to their original positions by
following the aforementioned steps in reverse.
Fig. 30
34
37
NOTE
○ When you remove paper-fi lter and nylon-fi lter, please
take care so that dust does not get inside the engine.
○ After rinsing in warm soap suds. Check to make sure that
the fi lter is dry before reassembly. An air fi lter that has
been used for some time cannot be cleaned completely.
Therefore, it must regularly be replaced with a new one.
A damaged fi lter must always be replaced.
Spark plug (Fig. 31, 32, 33)
1. Remove cleaner box (B) (32) and cleaner box (A) (37).
(Fig. 31)
2. Remove the spark plug by turning it counterclockwise
with the combi box spanner (6). (Fig. 32)
3. Clean the spark plug if it is dirty. Check the electrode
gap. The correct gap is 0.6 mm. (Fig. 33)
0.6 mm
11
32
33
38
35
36
Fig. 31
6
Fig. 32
Fig. 33