2-6 PERIODIC MAINTENANCE
SPARK PLUG
Inspect the spark plug condition, electrode color, carbon depos-
its, spark plug gap, and washer damage, after removing the
spark plug.
NOTE:
Remove the dirt around the spark plug before removing the
spark plug to prevent dirt from entering the combustion cham-
ber.
Inspect the porcelain tip color.
Clean the spark plug and check the spark plug gap with the
thickness gauge.
Standard Spark plug: NGK BR8EG
Spark plug gap: 0.5 – 0.6 mm (0.020 – 0.024 in)
09900-20803: Thickness gauge
Tighten the spark plug to the specified torque after tightening the
spark plug temporarily by hand.
Spark plug: 20 N·m (2.0 kgf-m, 14.5 lb-ft)
Porcelain tip color Cause
White (overheated)
• Hot type spark plug
• Advanced ignition timing
• Lean air/fuel mixture
• Deteriorated fuel
Black (fouled)
• Cold type spark plug
• Retarded ignition timing
• Rich air/fuel mixture
• Rich oil/gasoline mixture
CAUTION
Changing the spark plug heat range improperly can
damage the engine.
Select the spark plug heat range only after adjusting
the ignition timing, carburetor setting and oil/gasoline
mixture.
0.5 – 0.6 mm
(0.020 – 0.024 in)
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