SERVICING YOUR TRIMMER
37
Spark Plug Service
Recommended spark plug:
CMR5HSB (NGK)
Incorrect spark plugs can cause engine damage.
1. Remove the 5 x 12 mm hex bolt and top
cover.
2. Disconnect the spark plug cap, and remove
any dirt from around the spark plug area.
3. Remove the spark plug with a 5/8-inch spark
plug wrench.
4. Inspect the spark plug. Replace it if the
electrodes are worn, or if the insulator is
cracked or chipped.
5. Measure the spark plug electrode gap with a
suitable gauge. The gap should be
0.024 ~ 0.028 in (0.60 ~ 0.70 mm). Correct
the gap, if necessary, by carefully bending the
side electrode.
6. Install the spark plug carefully, by hand, to
avoid cross-threading.
7. After the spark plug seats, tighten with a
5/8-inch spark plug wrench to compress
the washer.
If reinstalling the used spark plug, tighten
1/8 ~ 1/4 turn after the spark plug seats.
If installing a new spark plug, tighten
1/2 turn after the spark plug seats.
A loose spark plug can overheat and damage
the engine. Overtightening the spark plug can
damage the threads in the cylinder head.
8. Attach the spark plug cap.
9. Install the top cover and 5 x 12 mm hex bolt
and tighten securely.
NOTICE
NOTICE
SPARK PLUGSPARK PLUG CAP
5/32 in (4 mm) HEX WRENCH
(commercially available)
TOP
COVER
5 x 12 mm
HEX BOLT
SPARK PLUG
CAP
SEALING
WASHER
SIDE ELECTRODE
0.024 - 0.028 in
(0.60 - 0.70 mm)
GAP