The most basic working principle of the magneto: when the permanent magnet rotates in the iron core, the primary coil on the iron core induces an electromotive force (called the primary potential). When the contact of the breaker is closed, a current (called the primary current) is generated. When the contact of the breaker is suddenly opened and the primary current is suddenly cut off, the secondary coil induces a relatively high electromotive force (called the secondary potential), causing the spark plug to jump. In order to obtain the strongest spark plug ignition, the maximum secondary potential should be obtained; In order to obtain the maximum secondary potential, the breaker contact should be closed when the primary potential is zero and open when the primary potential is maximum.
When is the primary potential maximum? The moment when the primary potential is maximum shall be when the pole of the permanent magnet turns 80 ° - 100 ° over the neutral position. This angle is called "position angle", which can ensure that the correct position of the breaker contact with respect to the cam can be obtained. This requirement can be met as long as the mark is aligned and installed. For example, when assembling C210 magneto, align the two opposite scribes on the breaker base plate and the casing, and align the pointer on the breaker with the scribe on the cam; When assembling C244 magneto, align the scribed lines on the large and small transmission gears, and on the casing and the breaker base plate respectively.
As for the requirement that the breaker contact should be closed when the primary potential is zero, as long as the position angle is correct and the contact gap is adjusted to the specified value, it can be met. Of course, adjusting the contact gap to the specified value is not only to meet this requirement, but also to avoid premature ablation of the contact when the contact is opened.
