2. When the engine is running, AC current is generated in the magneto stator. However, before the current leaves the stator, it is rectified to DC by the use of two diodes built into the stator base.

3. The DC current then flows from the stator along a single red colored wire to a junction under the seat of the motorcycle. There it connects to a purple wire which is, in turn, connected to a 15 ohm resistor housed in a black case mounted beneath the seat.

4. When the lights are off, the charging current must flow through the resistor before going to the battery, therefore charging it at a reduced rate. This is necessary because the only time current is drawn from the battery when the lights are off is when the brakes are applied and the brake light comes on, or when the horn is operated. If the battery were allowed to receive a full rate of charge when the lights were not in use, it probably would result in destruction of the battery due to overheating.

5. The resistor is connected to the headlight on and off switch by means of two wires, one from each terminal of the resistor. When the lights are turned on, these two wires are connected together which bypasses the resistor. Then the full amount of charging current can flow to the battery. The battery can now handle this charge because the lights are drawing considerable current from it.
 

Section 4:

Checking the Charging Circuit

2. If the battery does not seem to be charging properly, remove it and charge it for several hours on a battery charger that will allow 1 amp or less to flow into the battery. If it holds the charge, reinstall it in the motorcycle. If it does not, replace it, and in either case, check the fuse. It should be a 20 amp fuse.

3. Locate the group of three wires that run up the frame tube from the magneto. There will be one black wire, one blue wire, and one red wire coming from a black plastic tube. Follow the red wire until it connects to a purple wire. Slide back one of the insulators to expose the connector. Unplug the connection.

4. Clip one lead of an ohmmeter to the red wire and touch the other wire to ground. Read the meter; then reverse the leads. In one direction the meter should read infinity. In the other direction it should have a reading of from 12 to 15 ohms. (Fig. 147) If it does not, check the red wire all the way down to the point where it enters the epoxy on the magneto stator. If the wire has no breaks or cuts, replace the magneto assembly.

5. Clip the positive lead of a DC voltmeter to the end of the red wire and clip the negative lead of the voltmeter to any good ground. Start the engine and accelerate it to