17
4. Disconnect the spark plug wire.
5. Clean dirt from around the spark plug. Remove the
spark plug from the cylinder head by turning a 5/8 in.
socket counterclockwise.
6. Remove the engine cover (Fig. 33).
7. 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. 36). Remove the rocker arm cover and gasket.
3. Remove the screw behind the engine cover (Fig. 35).
Rocker Arm Cover
Screw
Fig. 35
Fig. 36
Spark Plug Hole
8. 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. 36)
• Both rocker arms move freely, and both valves are
closed
If these statements are not true, repeat this step.
9. 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 the intake and exhaust
is .003 – .006 in. (.076 – 0.152 mm).
Use a standard automotive feeler gauge at .005 (0.127mm).
The feeler gauge should slide between the rocker arm and
valve stem with a slight amount of resistance, without
binding. Figures 37 & 38 show how to measure the
clearance.
MAINTENANCE AND REPAIR INSTRUCTIONS
Adjusting Nuts
Feeler Gauge
Rocker Arms
Fig. 37
Fig. 38
Feeler Gauge
Exhaust
Adjusting Nut
Exhaust
Rocker Arm
Exhaust
Clearance:
.003-.006 in.
(.076-0.152 mm)
Exhaust Valve Stem
INTAKE
EXHAUST
Intake Valve
Stem
Intake Clearance:
.003–.006 in.
(.076–0.152 mm)
10. If the clearance is not within specification:
a. Turn the adjusting nut using a 5/16 inch (8 mm)
wrench or nut driver (Fig. 38).
• To increase clearance, turn the adjusting nut
counterclockwise.
• To decrease clearance, turn the adjusting nut
clockwise.
b. Recheck both clearances, and adjust as necessary.
11. Reinstall the rocker arm cover using a new gasket.
Torque the screw to 20–30 in
•
lb (2.2–3.4 N
•
m).
12. Reinstall the engine cover. Check alignment of the
cover before tightening the screws. Tighten screws.
13. Reinstall the muffler cover. Slip the rear tab on the
muffler cover into the engine cover rear slot. Then
slide the remaining slots into the tabs until they snap
into place (Fig. 33).
14. Check the spark plug and reinstall. See
Replacing
the Spark Plug
.
15. Replace the spark plug wire.
Summary of Contents for MP425
Page 1: ...Operator s Manual P N 769 02972 02 07 MP425 MP475 ...
Page 11: ......
Page 21: ...21 NOTES ...
Page 43: ...F21 REMARQUES ...
Page 65: ...E21 NOTAS ...
Page 66: ...E22 NOTAS ...
Page 67: ...E23 NOTAS ...
Page 68: ...E24 PARTS LIST ENGINE PARTS MODELS MP425 MP475 4 CYCLE GAS TRIMMERS ...
Page 71: ...E27 PARTS LIST BOOM AND TRIMMER PARTS MODEL MP475 4 CYCLE GAS TRIMMER ...
