- paul-ryan.info Normal: light browncolour. Dirty: powderydeposits. Black carbon: anover-rich mixture, ortoo much choke. Oil fouling: worn valves orpiston rings. Pre-ignition: causesthe inner electrode tobe burned away.
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Cleaning and fitting spark plugs

Check and clean sparkplugs every 5,000 miles (8,000 km) and replace them after 10,000 miles (16,...