The Magneto Single Fire unit is designed to provide spark to only the live cylinder on your motorcycle. They can be used in pairs if you have dual spark plugs.
1. Hook up a ground lead from a cap screw to one of the magneto cap ports, hook up the MSF unit to the other.
2. Plug the spark plug ends on; attempt to start motorcycle.
3. If you get no spark, your polarity is reversed. Switch either the wires on the plugs or in the magneto.
4. If you are running dual plugs, hook up a second MSF unit to the magneto, in place of the ground lead. NOTE: You will see that each unit has one of the spark plug leads marked with a red band. . These red legs MUST go to different cylinders for proper operation. For example, if MSF #1 runs the stock plugs with the red-tagged wire to the front cylinder, MSF #2 red-tagged wire goes to the rear added plug, and the untagged to the front added plug.
NOTE: Greater voltage is needed to spark the live cylinder plug (versus the exhaust cylinder plug) since it is under compression. Dual plug users should bear in mind that both of their sparks are live cylinder sparks, unlike the stock configuration of 1 live spark + 1 exhaust spark.