How is the strength of the magnet in a magneto checked?

• A. Run at high RPM and measure output voltage
• B. On a test stand, rotate at specified speed with breaker points open and measure primary current
• C. Measure coil resistance at room temperature
• D. Visual inspection of magnet

Answer: (B)

Testing magnet strength focuses on the magnetic circuit in a controlled, no-load condition. On a test stand, you spin the magneto at the prescribed speed and keep the breaker points open so the primary circuit isn’t completing a spark path. In this setup the primary current becomes a direct indicator of how strong the magnetic field is inside the magneto. If the magnets are strong, the magnetic flux interactions produce a reading within the standard range; if the magnets are weak, the reading will deviate. This method isolates the magnetic circuit from ignition effects, giving a reliable, repeatable measure of magnet strength. Measuring coil resistance, visual inspection, or testing secondary voltage under load can be influenced by other factors and don’t directly assess the magnet’s strength.