How to Distinguish Between Good and Bad Motorcycle Spark Plugs?
1 Answers
To determine whether a motorcycle spark plug is good or bad, the first step is to perform a spark test. When the spark plug accurately jumps from the center electrode to the negative electrode at the top of the spark plug, it is functioning normally. During the spark test, the spark plug must be grounded at the cylinder head or cylinder block. If the spark does not jump accurately to the upper electrode of the spark plug but instead jumps to other parts of the spark plug, it indicates a short circuit between the two electrodes. This is usually caused by carbon deposits and can be repaired by baking. Alternatively, upon close inspection, you may notice that the center electrode is biased to one side, but it fails to produce the correct spark during ignition! In such cases, replacing the spark plug is necessary to resolve the issue. The optimal operating temperature for a spark plug is generally between 400-800 degrees. If the spark plug appears black, it indicates that the operating temperature is too low, caused by an overly rich air-fuel mixture (or prolonged idling). If it appears white, it means the operating temperature is too high, due to an overly lean air-fuel mixture. The normal working state should be light brown. Remove the spark plug, place it against the cylinder block (connected to the high-voltage wire), and press the starter pedal to observe. Check if there is carbon buildup inside the spark plug, and clean it before testing again. If there is still no carbon buildup, the spark plug is essentially useless.
