Spark Plug - Suzuki RM250 Owner's Service Manual

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.
Porcelain tip color
White (overheated)
Black (fouled)
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.
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)
Cause
• Hot type spark plug
• Advanced ignition timing
• Lean air/fuel mixture
• Deteriorated fuel
• Cold type spark plug
• Retarded ignition timing
• Rich air/fuel mixture
• Rich oil/gasoline mixture
CAUTION
0.5 – 0.6 mm
(0.020 – 0.024 in)