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251030
10/15-Hour Maintenance
CAUTION!
Before removing the spark plug, clean
the area around the plug to prevent dirt
and dust from getting into the engine’s
internal parts.
Every 10 to 15 hours of operation:
n Remove and clean the spark plug.
See Figure 19. Adjust the spark plug
electrode gap to 0.024 inch (0.6 mm).
If the plug must be replaced, use only:
NGK CMR5H or equivalent.
n Lubricate the cutter assembly gear-
box by pumping one or two strokes of
Figure 28
Clean the spark
plug and check
the gap at the
electrode.
0.024 inch
(0.6 mm)
lithium-base grease into the grease fit-
ting using a lever-type grease gun. See
Figure 29.
Gearbox Grease
Fitting
WARNING!
The cutter blades are very sharp!
Always wear gloves when working
around the cutter assembly.
CAUTION!
Operating the trimmer with worn or
improperly adjusted cutters will reduce
cutter performance and may also dam-
age your machine.
Guide Bar
Locknut
Cutter Blades
Shoulder
Bolt
Washer
(should turn
freely)
Figure 26
Cutter Blade Adjustment
Figure 29
Cutter performance of your machine
depends in great measure on cutter blade
clearance. Properly adjusted blades will
oscillate freely yet help prevent binding of
cut material between blades. Adjust blades
as follows (Figure 26):
1. Loosen all blade locknuts at least one
full turn.
2. Tighten each blade shoulder bolt firmly,
and then loosen the shoulder bolts 1/4
to 1/2 turn.
3. Working from the gearcase end, lock
each bolt in place by firmly tightening
its locknut while preventing the shoul-
der bolt from turning.
When shoulder bolt adjustment is cor-
rect, there should be a gap of 0.25–0.50
mm between the cutter blades and the flat
washers, and the flat washer beneath each
bolt head should turn freely.
CAUTION!
Over lubricating can cause the gear-
box to operate sluggishly and can
cause grease to leak out.
10-Hour Maintenance
Unscrew
Fasteners
Figure 27A
(more frequently in dusty
conditions)
1. Remove the air cleaner cover by loosen-
ing the thumb screws and lifting up. See
Figure 27A.
2. Remove and inspect the pre-filter. If the
pre-filter is torn or otherwise damaged,
replace it with a new one. See Figure 27B.
3. Clean the pre-filter with soap and water.
Let dry before reinstalling.
4. Inspect the air cleaner element. If the
element is damaged or distorted, re-
place it with a new one.
5. Tap filter gently on a hard surface to
dislodge debris from element or use
compressed air from the inside to blow
debris out and away from the air filter
element.
CAUTION!
Never operate the unit if the air cleaner
assembly is damaged or missing!
IMPORTANT!
Direct the air stream at the inside face of
the lter only!
6. Install the filter element, pre-filter and
cover in the reverse order of removal.
Figure 27B
Filter
Element
Pre-Filter