This is from outboard ignition frequently asked questions, im not sure what to make of it
The trigger or timerbase (term varies by manufacturer) is basically the same thing as a distributor. This component is also mounted under the flywheel and also uses the flywheel for it's operation. The center hub on the flywheel also contains magnets mounted in a 360 degree configuration. Instead of generating electrical current though, these magnets simply tell the trigger/timerbase what position the crankshaft is at. As the magnets pass by the pickup sensors, the trigger/timerbase sends a signal to the power pack, telling it the precise moment to release its stored energy to the specific cylinder. The spark timing is controlled exclusively by the trigger/timerbase. As the component rotates with increase or decrease of the throttle, so does the park timing. Smooth and accurate movement of this device is critical to a good running motor.