honda-power-equipment hht31s ユーザーズマニュアル

Spark Plug Service
Recommended spark plugs:
HHT25S

CMR5HSB (NGK)

HHT31S

CR5HSB (NGK)
U16FSR-UB (DENSO)

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.

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)