Craftsman 316.79191 - Manual (Page 12)

12
MAINTENANCE AND REPAIR INSTRUCTIONS
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 screwdriver in between the Air
Filter Cover and the Engine Cover (Fig. 33). Turn the idle speed
screw in, clockwise, 1/8 of a turn at a time (as needed) until
the engine idles smoothly.
NOTE: The cutting head should not rotate when the engine idles.
3.
If the cutting attachment rotates when the engine idles, turn
the idle speed screw counterclockwise 1/8 of a turn at a time
(as needed), until the head stops turning.
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 serviced 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
the first 10 hours of operation and 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 six (6) screws on the back of the engine cover
with a Flat-head or T-25 Torx screwdriver (Fig. 34).
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.
34).
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. 35). 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. 36)
• 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. 36 & 37). Measure both the intake
and exhaust valves.
Rocker
Arm
Cover
Fig. 35
Spark
Plug
Hole
plate (Fig. 31).
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. 32).
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. 33).
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 idle speed problems. 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 idle. 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
Idle Adjustment Screw
Fig. 33
Fig. 31
Locking
Tab
Tabs Back Plate
Air
Filter
Air Filter Cover
Air Filter
Tab
Fig. 32
WARNING: The cutting head may spin during idle speed
adjustments. Wear protective clothing and observe all
safety instructions to prevent serious personal injury.
WARNING: The cutting attachment may spin during idle
speed adjustments. Wear protective clothing and observe
all safety instructions to prevent serious personal injury.
WARNING: To prevent serious personal injury, make
sure the cutting attachment has stopped rotating before
you turn it off and set it down.
Remove
Screws
Fig. 34
View Of The Rear Engine Cover
Remove
Screws
Fig. 30