HONDA HHT31S - Manual (Page 39)

SERVICING YOUR HONDA TRIMMER
37
Spark Plug Service
Recommended spark plugs:
HHT25S
CMR5HSB (NGK)
HHT31S CR5HSB (NGK)
U16FSR-UB (DENSO)
Incorrect spark plugs can cause engine damage.
1. HHT25S model: 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.
HHT25S model: Install the top cover and
5 x 12 mm hex bolt and tighten securely.
TORQUE: 51.6 in-lb (1.09 N•m)
NOTICE
NOTICE
SPARK PLUG
SPARK PLUG CAP
SPARK PLUG SPARK PLUG CAP
HHT25S
HHT31S
HHT25S
5/32 in (4 mm) HEX WRENCH
(commercially available)
TOP
COVER
5 x 12 mm
HEX BOLT
SPARK PLUG
CAP
0.024 - 0.028 in
(0.60 - 0.70 mm)
SEALING
WASHER
SIDE ELECTRODE SIDE ELECTRODE
GAP
HHT31S HHT25S