Magneto Stator coil testing
Learn how to properly test your magneto, stator or pickup coils. This works for breaker point and CDI type ignition systems. The main tools you will need to do these tests are 1) The Service Manual for your particular bike 2) an inexpensive multi-meter to measure ohms of resistance.
How does one go about diagnosing a "no spark" situation? First off the most common reason for no spark is that some component in the ignition system is grounding of the circuit. Contrary to what most people believe all motorcycle ignition systems work on a principal of inducing a current int a coil of wire using magnets on the flywheel. If a component in the system is able to allow that induced current to find a path of least resistance, a ground, the current will go there instead of making its way to the electrode of the spark plug to jump the gap.
Most common components to check in the ignition, refer to your service manual for more detail and proper procedures.
Kill Switch: be sure it is not ground out the ignition, disconnect for testing.
Spark plug: be sure it is the correct type, heat range, and thread depth, replace with a new plug or know working plug for testing
Breaker point(s) and condenser: replace rather than testing, these parts commonly fail due to age and wear, they are VERY common for causing "no spark"
Magneto coils: as seen in the video above, for vintage bikes this is the most common reason for not having spark, the insulation has broken down so current induction cannot occur.
Spark plug coil: testing cannot be conclusive as the secondary windings cannot be reliably tested as there is no way to test for high current or high heat breakdown, replace with a known good part for testing
CDI box: It is very rare for these to fail as there is no moving parts and they are generally sealed well from the elements, this is the last thing to suspect, replace with known good part for testing
How does one go about diagnosing a "no spark" situation? First off the most common reason for no spark is that some component in the ignition system is grounding of the circuit. Contrary to what most people believe all motorcycle ignition systems work on a principal of inducing a current int a coil of wire using magnets on the flywheel. If a component in the system is able to allow that induced current to find a path of least resistance, a ground, the current will go there instead of making its way to the electrode of the spark plug to jump the gap.
Most common components to check in the ignition, refer to your service manual for more detail and proper procedures.
Kill Switch: be sure it is not ground out the ignition, disconnect for testing.
Spark plug: be sure it is the correct type, heat range, and thread depth, replace with a new plug or know working plug for testing
Breaker point(s) and condenser: replace rather than testing, these parts commonly fail due to age and wear, they are VERY common for causing "no spark"
Magneto coils: as seen in the video above, for vintage bikes this is the most common reason for not having spark, the insulation has broken down so current induction cannot occur.
Spark plug coil: testing cannot be conclusive as the secondary windings cannot be reliably tested as there is no way to test for high current or high heat breakdown, replace with a known good part for testing
CDI box: It is very rare for these to fail as there is no moving parts and they are generally sealed well from the elements, this is the last thing to suspect, replace with known good part for testing