Craftsman 316.7948, Руководство оператора

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12
Checking the fuel, cleaning the air filter, and adjusting the idle
speed should solve most engine problems. If not and all of the
following are true:
• the engine will not idle
• the engine hesitates or stalls on acceleration
• there is a loss of engine power
Have the carburetor adjusted by a Sears or other qualified service dealer.
ROCKER ARM CLEARANCE
This requires disassembly of the engine. If you feel unsure or unqualified
to perform this, take the unit to a Sears or other qualified service dealer.
NOTE: Inspect the valve to rocker arm clearance with a feeler
gauge after every 25 hours of operation.
• The engine must be cold when checking or adjusting the valve
clearance.
• This task should be performed inside, in a clean, dust free area.
1. Remove the seven (7) screws on the back of the engine cover
with a Flat-head or T-25 Torx screwdriver (Fig. 31).
2. Disconnect the spark plug wire.
3. Clean dirt from around the spark plug. Remove the spark plug
from the cylinder head by turning a 5/8 in. socket
counterclockwise.
4. Remove the engine cover (Fig. 31).
5. Clean dirt from around the rocker
arm cover. Remove the screw
holding the rocker arm cover with a
large flat blade screwdriver or Torx T-
25 bit (Fig. 32). Remove the rocker
arm cover and gasket.
6. Pull the starter rope slowly to bring
the piston to the top of its travel,
(known as top dead center). Check
that:
• The piston is at the top of its travel.
Look in the spark plug hole to view
the piston (Fig. 33).
• Both rocker arms move freely, and
both valves are closed.
If these statements are not true, repeat step 6.
7.
Slide the feeler gauge between the rocker arm and the top of each
valve stem. Measure the clearance between the valve stem and
rocker arm (Fig. 33). Measure both the intake and exhaust valves.
The recommended clearance for both intake and exhaust is .003 –
.006 in. (.076 – 0.152 mm). Use a standard automotive .005 in.
(0.127 mm) feeler gauge. The feeler gauge should slide between
the rocker arm and valve stem with a slight amount of resistance,
without binding. See Figures 33 and 34.
8.
If the clearance is not within specification:
a. Turn the adjusting nut using a 5/16 inch (8 mm) wrench or nut
driver (Fig. 33).
• To increase clearance, turn the adjusting nut counterclockwise.
• To decrease clearance, turn the adjusting nut clockwise.
6. Replace the filter (Fig. 25).
NOTE: If the unit is operated without the
air filter, you will VOID the warranty.
7. Reinstall the air filter cover. Position
the slots on the top of the air filter
cover onto the tabs at the top of the
back plate (Figs. 25 & 29).
8. Swing the cover down until the tab
on the air filter backplate snaps
into place in the slot on the air filter
cover (Fig. 29).
IDLE SPEED ADJUSTMENT
The idle speed of the engine is
adjustable. An idle adjustment screw
is between the air filter cover and the
engine starter housing (Fig. 30).
NOTE: Careless adjustments can
seriously damage your unit.
Aside from the idle speed,
only a Sears or other qualified
service dealer should make
carburetor adjustments.
1. Check Fuel
Old fuel is usually the reason for
improper unit performance. Drain
and refill the tank with fresh fuel
prior to making any adjustments. Refer to Oil and Fuel Information.
2. Clean Air Filter
The condition of the air filter is important to the operation of the unit.
A dirty air filter will restrict air flow. This is often mistaken for an out
of adjustment carburetor. Check the condition of the air filter before
adjusting the idle speed screw. Refer to Air Filter Maintenance.
3. Adjust Idle Speed Screw
If, after checking the fuel and cleaning the air filter, the engine still
will not idle, adjust the idle speed screw as follows:
1.
Start the engine and let it run at a high idle for a minute to
warm up. Refer to Starting/Stopping Instructions.
2. Release the throttle trigger and let the engine idle. If the engine
stops, insert a small phillips in between the Air Filter Cover and the
Engine Cover (Fig. 30). Turn the idle speed screw in, clockwise,
1/8 of a turn at a time (as needed) until the engine idles smoothly.
MAINTENANCE AND REPAIR INSTRUCTIONS
Rocker
Arm
Cover
Fig. 32
Spark
Plug
Hole
Air Filter Cover
Air Filter
Back Plate
Tab
Fig. 29
Idle
Adjustment
Screw
Fig. 30
Fig. 27 Fig. 28
Remove
Screws
Fig. 31
Remove
Screws
Fig. 26