Honda HRS21 Owner's Manual page 32

Spark Plug
Standard Plug: BR-4HS (NGK)
W14FR-U (ND)
1. Disconnect the cap and remove the spark plug.
2. Visually inspect the plug. Discard the plug if it is heavily deposited or if
the insulator is cracked or chipped.
3. Measure the plug gap with a wire-type feeler gauge; it should be
0.7-0.8 mm (0.028-0,031 in). If adjustment is necessary, bend the
side electrode carefully.
4. Make sure the sealing washer is in good condition, then thread the spark
plug in by hand until it seats.
5. Use the wrench to tighten a new plug l/2 turn further to compress the
washer. If you are reusing the plug, it should only take l/8- l/4 turn
after the plug seats.
6. Replace the spark plug cap.
SPARK PLUG WRENCH
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/ --I
SIDE ELECTRODE
0.7-0.8 mm
(0.028-0.031 in)
30