MSD Electronic Ignition

The Capacitive Discharge Electronic Ignition Module, part number KT-4150 made by MSD provides a long duration 30,000 volt spark and works excellent on the Cushman Scooter. This page details how to connect the MSD to a 12-volt Cast Iron Eagle. A means for charging a small 7 to 14 ampere hour motorcycle battery is included. MSD suggests using two 6 cell 7.2 volt model car Ni-Cad batteries to power the unit and the Ni-Cads could also be charged from the circuit diagramed below. Unless weight is factor a motorcycle battery is more practical because the capacity of the Ni-Cads is less than 2 ampere hours.

The MSD system consists of an electronic module, a special ignition coil, and a heavy-duty high-tension spark plug lead. These items are diagrammed below along with the wire colors used by MSD. The unit uses the original points since a Hall effect magnetic sensor cannot be used with a multiple magnet system like a Cushman has. The MSD electronic module has a high impedance input and the points become much less critical than when running the original magneto coil. The unit will blast a spark over half an inch every time the points open, regardless of engine RPM. Fouled spark plugs become a thing of the past. The unit has a built in LED test lamp that indicates if the points are open or closed. By Connecting the MSD to the points with a small two pin trailer type connector the scooter can be returned to conventional magneto operation in less than 30 seconds in the event of battery failure.