9
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. 37). 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
(Fig. 36 and 37).
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. 37).
• 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 part number 753-05784 or Champion® RDZ4H spark
plug. The correct air gap is 0.025 in. (0.635 mm).
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. 33).
2. Grasp the plug wire firmly and pull the cap from the spark plug.
3. Clean dirt from around the spark plug. Remove the spark plug from the
cylinder head by turning a 5/8 in. socket counterclockwise.
3. Replace cracked, fouled or dirty spark plug.
Set the air gap at
0.025 in. (0.635 mm)
using a feeler gauge (Fig. 38).
4. 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.
MAINTENANCE AND REPAIR INSTRUCTIONS
WARNING:
Do not sand blast,
scrape or clean electrodes. Grit in the
engine could damage the cylinder.
5. Squeeze the filter to spread and remove
excess oil.
6. Replace the air filter into the base plate
(Fig. 31).
NOTE:
If the unit is operated without the air
filter, you will
VOID
the warranty.
7. Reinstall the air filter cover. Position the two
small tabs on the air filter cover into the two
slots in the back plate and press the air filter
cover down, making sure to align the lock tab with the lock tab slot, until
it snaps into place (Fig. 29 and 30).
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. 32).
NOTE:
Careless adjustments can seriously damage your unit. An authorized
service dealer should make carburetor adjustments.
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 and 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. 32). 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 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 an authorized service dealer.
ROCKER ARM CLEARANCE
This adjustment requires disassembly of the
engine. If feeling unsure or unqualified to
perform this, take the unit to an authorized
service center.
• 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. 33).
2. Remove the engine cover (Fig. 34).
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. 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. 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 while looking in the spark plug hole
(Fig. 35)
• Both rocker arms move freely, and both valves are closed
WARNING:
To avoid serious
personal injury, always turn the unit
off and allow it to cool before
cleaning or servicing it.
WARNING:
The cutting
attachment may spin during idle
speed adjustments. Wear protective
clothing and observe all safety
instructions to prevent serious
personal injury.
Fig. 31
Air Filter
Back
Plate
Fig. 32
Fig. 33
Fig. 34
Fig. 35
Idle
Adjustment
Screw
Remove Screws
Muffler
Engine
Cover
Rocker Arm
Cover
Screw
Spark Plug
Hole
Fig. 36
Fig. 37
Fig. 38
Adjusting Nuts
INTAKE
Rocker
Arms
EXHAUST
Valve Stem
Exhaust
Adjusting
Nut
Feeler
Gauge
Rocker Arm
0.025 in.
(0.635 mm)
0.003–0.006 in.
(0.076–0.152 mm)