Craftsman 316.79617 - Manual (Page 12)

12
MAINTENANCE AND REPAIR INSTRUCTIONS
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 screwdriver in between
the Air Filter Cover and the Engine Cover (Fig. 29). 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 attachment 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 attachment 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 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 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. 30).
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. 30).
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. 31). 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 while looking in the spark
plug hole (Fig. 32)
• Both rocker arms move freely, and both valves are closed.
If these statements are not true, repeat this step.
7. Slide the feeler gauge between the rocker arm and the
valve return spring. Measure the clearance between the
valve stem and rocker arm (Fig. 32 & 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 31 and 32.
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.
b. Recheck both clearances, and adjust as necessary.
9. Reinstall the rocker arm cover using a new gasket. Torque
the screw to 20–30 in•lb (2.2–3.4 N•m).
10. Check the spark plug and reinstall. See Replacing the
Spark Plug.
11. Replace the spark plug wire.
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. 30
View Of The Rear Engine Cover
Remove
Screws
Rocker
Arm
Cover
Fig. 31
Spark
Plug
Hole
Adjusting Nuts
Feeler Gauge
Rocker Arms
Fig. 32
INTAKE
EXHAUST
Spark Plug
Hole