1. Lean Air-Fuel Mixture: When the air-fuel mixture in the engine is too lean (lacking enough fuel), it can lead to higher combustion temperatures and cause the spark plug to appear reddish. A lean mixture can result from various factors, such as a clogged fuel injector, a vacuum leak, or an issue with the fuel pump.
2. Overheating: Excessive heat in the engine can discolor the spark plug and turn it reddish. This can occur due to several reasons, including a faulty cooling system, such as a malfunctioning thermostat or low coolant levels, or issues with the engine's ignition timing.
3. Incorrect Spark Plug: Using an incorrect spark plug type or one with an improper heat range can lead to overheating and reddish discoloration. Check the owner's manual to ensure you're using the recommended spark plug for your Yamaha Zuma.
4. Worn-Out Spark Plug: In some cases, worn-out spark plugs can exhibit reddish deposits. If the spark plug has accumulated excessive wear or has been in use for an extended period, it's advisable to replace it with a new one.
It's essential to identify the underlying cause of the reddish color on the spark plug to prevent potential engine damage. If you're not comfortable troubleshooting and fixing the issue yourself, it's best to consult a professional mechanic or take your Yamaha Zuma to an authorized service center for proper diagnosis and repair.
