Craftsman INCREDI.PULL 316.792021 Operator's Manual page 10

Third, Adjust Idle Speed Screw
WARNING:
The cutting attachment may spin during idle speed
adjustments. Wear protective clothing and observe all safety
instructions to prevent serious personal injury.
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 or flat blade
screwdriver into the hole in
the air filter/muffler cover (Fig. 39). 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), to
reduce idle speed.
Checking the fuel, cleaning the air filter, and adjusting the idle speed should
solve most engine problems. If not and any of the following are true have the
unit serviced by a Sears or other qualified service dealer:
• the engine will not idle
• the engine hesitates or stalls on acceleration
• there is a loss of engine power
ROCKER ARM CLEARANCE
WARNING:
To avoid serious personal injury, always turn the unit
off and allow it to cool before cleaning or servicing it.
This requires disassembly of the engine. If unsure or unqualified to perform
this maintenance, take the unit to a Sears or other qualified service center.
NOTE: Inspect the valve to
rocker arm clearance
with a feeler gauge after
the first 25 hours of
operation and then every
25 hours of operation
thereafter.
• 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 two (2) screws on
back of the engine cover and
the one on the front of the
engine cover with a Flat-head
or T-25 Torx screwdriver (Fig.
40).
2. Remove the engine cover
(Fig. 41).
3. Disconnect the spark plug
wire.
4. Clean dirt from around the
spark plug. Remove the
spark plug from the cylinder
head by turning a 5/8 in. (16
mm) socket
counterclockwise.
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. 42). 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. This should be done by looking into the
spark plug hole. (Fig. 42)
MAINTENANCE & REPAIR INSTRUCTIONS
Idle Adjustment
Screw
Fig. 39
Remove Screws
Fig. 40
Engine
Muffler
Fig. 41
Screw
Rocker Arm
Cover
Spark Plug
Hole
Fig. 42
• 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. 43). 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. Figure 43
and 44 show how to measure the
clearance.
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. 43).
• 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.
12. Reinstall the engine cover. Check alignment of the cover before
tightening the screws. Tighten screws.
REPLACING THE SPARK PLUG
Use a replacement Champion
0.025 in. (0.635 mm). Remove the plug after every 25 hours of operation and
check its condition.
1. Stop the engine and allow it to cool. Remove the two (2) screws on
back of the engine cover and the one on the front of the engine cover
with a Flat-head or T-25 Torx screwdriver (Fig. 40).
2. Grasp the plug wire firmly and pull the cap from the spark plug.
WARNING:
electrodes. Grit in the engine could damage the cylinder.
3. Clean dirt from around the
spark plug. Remove the
spark plug from the cylinder
head by turning a 5/8 in.
socket counterclockwise.
Cover
4. Replace cracked, fouled or
dirty spark plug. Set the air
gap at 0.025 in. (0.635 mm)
using a feeler gauge (Fig. 45).
5. Install a correctly-gapped
spark plug in the cylinder
head. Turn the 5/8 in. socket
clockwise until snug.
If using a torque wrench, torque to: 110-120 in.•lb. (12.3-13.5 N•m)
Do not over-tighten.
10
INTAKE
Rocker
Arms
Fig. 43
Exhaust
Adjusting
Nut
0.003–0.006 in.
(0.076–0.152 mm)
Fig. 44
® RDZ4H spark plug. The correct air gap is
Do not sand blast, scrape or clean spark plug
0.025 in.
(0.635 mm)
Fig. 45
Adjusting Nuts
EXHAUST
Rocker Arm
Feeler
Gauge
Valve Stem