Craftsman 25cc - Propane Curved Shaft Trimmer Powered by Lehr Operation Manual page 18

MAINTENANCE
ROCKER ARM CLEARANCE ADJUSTMENT
5. Clean dirt from around the rocker arm cover.
6. Remove the three screws holding the rocker arm
cover with a phillips head screwdriver.
7. Remove the rocker arm cover and gasket (Fig. 43).
Rocker Arm Cover
Screws
Rocker Arm
Cover
8. Pull the starter rope slowly to bring the piston to
the top of its travel, (This position is known as top
dead center).Check that the piston is at the top of
its travel by looking down into the spark plug hole.
Both valves should be closed and the rocker arms
should move freely. If this statement is not true,
repeat this step.
9. Slide a feeler gage between the rocker arm and the
valve return spring. Measure the distance between
the rocker arm and valve stem (Fig. 44) Take care
to only measure the free play. It is very easy to
insert too thick a feeler gauge and accidentally
depress the valve and spring. Measure both the
intake and exhaust valve distances.
10. Check the spark plug and reinstall (See Replacing
the Spark Plug (p.14) .
11. Reinstall the spark plug wire.
Adjusting Screws
Jam Nuts
Fig.44
18
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Fig.43
Rocker Arm
Feeler Gauge
Exhaust Valve
Intake Valve
IF THE CLEARANCE IS NOT WITHIN SPECIFICATION
1. Loosen the jam nut and turn the adjusting screw
as necessary. To increase the clearance, turn the
adjusting screw CCW. To decrease the clearance,
turn the adjusting screw CW.
2. Tighten the jam nut when the clearance is set.
3. Recheck the both clearances. Readjust if necessary.
4. Reinstall the rocker arm cover using a new gasket.
5. Tighten cover screws evenly until snug.
6. Reinstall the engine cover checking the alignment of
the cover. Tighten the four engine cover screws until
snug.
• The recommended clearance for both intake and
exhaust is 0.076-0.152mm (0.003-0.006in).
• Use a standard automotive 0.127mm (0.005in) feeler gage.
WARNING:
TO PREVENT SERIOUS INJURY, NEVER PERFORM
MAINTENANCE OR REPAIRS WITH UNIT RUNNING.
ALWAYS SERVICE AND REPAIR A COOL UNIT. DISCON-
NECT THE SPARK PLUG WIRE TO ENSURE THAT THE
UNIT CANNOT START.