The magneto is an important electrical device for motorcycles. The magneto consists of the magneto rotor and the magneto stator windings. The stator windings include the charging winding that provides the working power to the ignition system and the power winding that provides the working power to the charging system. As the motorcycle is used for a longer period of time and influenced by various factors, the magnetism of the magneto rotor will gradually weaken. When the magneto rotor loses its magnetism severely, it will affect the normal operation of the charging winding and the power winding, causing the effective value of the alternating output voltage of the charging winding and the power winding to decrease, thereby affecting the normal operation of the ignition system and the charging system. 

The first symptom to appear is difficulty in starting the engine. This is caused by the weakened high-voltage ignition spark generated by the ignition system during the engine starting condition. Next, the battery will also experience a state of low power, which is due to the reduced output power of the charging system. 

Under normal circumstances, difficulty in starting a motorcycle is more likely to draw the attention of drivers and maintenance personnel. Maintenance personnel will first consider that the ignition system has malfunctioned, and then proceed to conduct inspections and tests. They rarely check for any demagnetization faults in the rotor of the magneto. Besides, in the absence of specialized equipment, there are not very good methods for checking whether there is a demagnetization fault in the rotor of the magneto. In most cases, they use a screwdriver to touch the magnetic steel of the magneto rotor and feel the force of the magnetic steel with their hands to determine whether there is a demagnetization fault in the rotor. Due to the lack of a certain reference object for comparison and verification, the accuracy of the inspection and judgment is relatively low. 

When the high-voltage ignition spark of the ignition system weakens, causing difficulties in starting the engine, and after inspection and testing it is determined that there is a suspicion of fault in the charging winding, we should first analyze and determine whether the fault is caused by the charging winding or the failure of the magnetic motor rotor to magnetize. We can make this judgment based on the phenomenon that after the magnetic motor rotor loses magnetization, the effective value of the alternating output voltage of the charging winding and the power supply winding will significantly decrease. 

Disconnect the connection between the charging winding connection wire and the connector of the cable assembly. Use the AC voltage range of the multimeter to detect the AC voltage output by the charging winding. Use the foot start or the electric start to make the engine enter the starting condition, and record the reading of the multimeter. 

If it is confirmed through testing that the effective value of the alternating output voltage of the charging winding is significantly lower than the normal value, then the effective value of the alternating output voltage of the power winding should be tested next. Disconnect the connection between the power winding connection wire and the cable connector. Use the AC voltage range of the multimeter to measure the effective value of the alternating output voltage of the power winding, and record the reading of the multimeter. 

If the test confirms that the effective value of the AC output voltage of the power winding is significantly lower than the normal value, it can be determined that there is a de-magnetization fault in the rotor of the magnetic motor. In this case, the rotor of the magnetic motor should be magnetized or replaced. 

If the test results confirm that the effective value of the AC output voltage of the power winding is normal, then it can be determined that the technical condition of the magnetic motor rotor is good. This indicates that there is indeed a fault in the charging winding, which has caused the ignition spark at high voltage to weaken. Therefore, a new charging winding should be replaced. 

The advantage of doing this is that through detection and inspection, the suspected fault points can be identified as soon as possible, and the faults can be eliminated more quickly. If it is confirmed through testing that the effective value of the AC output voltage of the charging winding has significantly decreased, then the charging winding should be replaced for comparative inspection. If the fault of weakened high-voltage ignition spark still cannot be eliminated, then the check should be conducted on whether the rotor of the magneto has lost its magnetism, which will increase the operation time. 

If the first step is to check whether there is a loss of magnetism fault in the rotor of the magnetic motor, and if it is confirmed that there is a loss of magnetism fault in the rotor, then the rotor of the magnetic motor can be replaced for a comparative test. If it is confirmed that there is no loss of magnetism fault in the rotor, then the fault suspicion can be focused on the charging winding, and then the fault can be eliminated, which will achieve twice the result with half the effort. 

The difficulty in starting caused by magnet failure actually has an easier solution, which is to directly replace the DC igniter. However, when the charging is weak, there is no good solution for this problem. 

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