Have you stopped to look at the appearance of the spark plugs on your motorcycle ? You have to know that many times the spark plugs present symptoms that make it possible to detect faults in the engine . For this reason, we present a visual analysis of the ignition tips of the spark plugs so that you do not overlook possible problems that may come in the future.
Tell me how the spark plug is, and I’ll tell you what’s wrong with the engine.
Many faults are perfectly diagnosable after a simple glance, so we are going to see each of the scenarios that you can find when doing maintenance on your motorcycle :
Index of contents
#1 Waste impurities
Symptoms: The engine fails when it works at a high speed or when the car carries a heavy load.
Spark plug appearance: Insulator and electrodes covered by scale, usually white.
Causes: Oil leaks through the piston rings or poor quality gasoline, which generates residues that solidify on the tip of the spark plug.
Solution: Depending on the case, repair possible oil leaks or change the brand of fuel. The spark plug can be cleaned, but its replacement is recommended.
#2 Coal deposits
Symptoms: Difficulty starting. Misfiring and poor performance in slow gears.
Spark plug appearance: The ignition tip is completely covered with carbon residue.
Causes: Driving at low speed for long periods, air/fuel mixture too rich, faulty ignition system, delayed distributor or too cold spark plug.
Solution: From point 1 to 4. Make the necessary arrangements. In point 5 use hotter types of plug or with a lower thermal degree.
#3 Oil tanks
Symptoms: Difficulty starting the engine. Misfiring and poor performance in slow gears.
Spark plug appearance: The ignition tip is oily, wet and black.
Causes: Leaking piston rings and/or worn/damaged cylinder and, in 2-stroke engines, the oil to fuel ratio is too high (too much oil).
Solution: Change the rings or rectify the cylinders. Hotter plugs can be used as a temporary solution or use the proper oil/fuel ratio.
#4 Overheating (A)
Symptoms: Engine knocks. Loss of power at high speed, on climbs or with heavy loads.
Spark Plug Appearance Porcelain insulator is white, glassy and/or shiny and accumulated sludge has fused into ceramic.
Causes: The octane number used is too low, the ignition timing is too early, the cooling system is not working properly, poor air/fuel mixture, insufficient spark plug torque or spark plug too hot.
Solution: Depending on the case, check for possible anomalies in the engine or use colder spark plugs (higher thermal degree).
#5 Overheating (B)
Symptoms: Engine knocks. Loss of power at high speed, on climbs or with heavy loads.
Spark plug appearance: The surface of the insulator and electrodes is burned and covered by small granular residues.
Causes: The octane number used is too low, the ignition timing is too early, the cooling system is not working properly, poor air/fuel mixture, insufficient spark plug torque or spark plug too hot.
Solution: Depending on the case, check for possible anomalies in the engine or use colder spark plugs (higher thermal degree).
#6 Broken insulator
Symptoms: Poor engine performance.
Spark plug appearance: The porcelain tip of the insulator is broken or cracked.
Causes: Breakage is usually caused by a thermal shock (sudden rise or fall in temperature). If porcelain flakes off the spark plug, it can damage cylinders, valves, and pistons. The use of inadequate tools for the adjustment between the electrodes can cause the breakage of the insulator.
Solution: Check the motor parameters and use the appropriate tool for the adjustment of the gap between the electrodes. Replace the spark plug.
#7 Preignition
Symptoms: Great loss of power. The temperature rises, causing damage to the piston.
Spark plug appearance: Melted electrodes. In severe cases, the center electrode may disappear and the porcelain insulator may melt.
Causes: Prolonged driving at high speed, the ignition timing is too early or the cooling system is not working properly
There are sources of overheating in the combustion chamber
spark plug too hot
Solution: For points 2 and 3, adjust the ignition point and check the cooling system, for point 4, remove impurity residues and for point 5, use colder spark plugs.
#8 Rust
Symptoms: The engine does not work correctly (very weak spark gap).
Spark plug appearance: The electrode material appears oxidized and in extreme cases takes on a greenish color.
Causes: Rust and corrosion can appear for various reasons: use of poor quality fuel, humid environments, vehicles without use for long periods of time.
Solution: Replace the spark plug.
#9 Abnormal wear
Symptoms: Difficulty starting and loss of engine power.
Spark plug appearance: The electrodes appear very worn in the spark gap area, so the distance between them is very pronounced.
Causes: It is usually due to corrosion, oxidation or reaction with the lead existing in some gasolines.
Solution: Replace the spark plug.
#10 Normal conditions
Symptoms: The spark plug works correctly.
Spark plug appearance: The tip of the spark plug is often covered in brown and/or grayish deposits.
Causes: The spark plug works correctly. The engine performs satisfactorily and fuel consumption is normal.
Solution: Spark plugs must follow certain maintenance. Clean them and adjust the gap between electrodes. Respect the change intervals.
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