The 6 volt electrical system of the Aermacchi Harley-Davidson Sprint, Models C and H from 1964 to 1966, drawn circuit by circuit. Each wire is labelled with its colour.
Always check a wire with a multimeter before you connect it, and disconnect the battery first.
Circuit 1Power from the batteryThe positive goes to the terminal board and through the fuse to the ignition switch. The negative goes to earth.
Circuit 2ChargingThe generator charges the battery through the regulator. The warning lamp sits between the regulator and the power after the ignition switch.
Circuit 3IgnitionAfter the ignition switch the current goes through the board to the coil. The points switch the coil, and the coil gives the spark to the plug.
Circuit 4LightingThe switch sends current through the board to the dip switch and the headlamp. The brown wire feeds the tail light and the speedometer lamp.
Circuit 5Stop lightThe stop light switch gets power from the board and passes it on to the stop light.
Circuit 6HornThe horn gets power after the ignition switch. The button in the dip switch makes the earth.
BulbsWhich bulb goes whereRating and part number for this model
| Lamp | Rating | Part no. |
|---|---|---|
| Headlamp (sealed beam) | 30/30 W | 67716-68 |
| Tail and stop light | 3/21 cp | 68165-47 |
| Turn signal, if fitted | 21 cp | 68572-50 |
| Speedometer lamp | 3 W | 67291-64P |
| Speedometer lamp, Model H | 2 cp | 68462-49 |
| High beam and generator warning lamps | 1.5 W | 71090-61P |
The table lists two speedometer lamps for the Model H: 3 W and 2 cp. Check which one fits your instrument.
From the bulb table in the workshop manual. These are old Harley-Davidson part numbers. cp stands for candlepower, the old unit of light output.
Read this firstWatch out forUncertain colours and terminals
- This is a 6 volt system with a DC generator and a 20 amp fuse.
- The positions on the terminal board have no readable number in the drawing. Positions 1 to 4 are left of the fuse, 5 to 8 right of it, counted from left to right.
- Where wires disappear into the loom, the connection was worked out from colour and function. Check those connections with a meter.
- Up to 1964 there is an emergency start switch with four wires: red, blue, white and brown. Only the normal current path is drawn here. Check the emergency position with a meter.
- The high beam warning lamp was only fitted from late 1966.
- High and low beam were worked out from the wire that carries the high beam warning lamp. Check this at the headlamp.
- The headlamp has a blue wire to earth.
Our own drawings per circuit. The connections are based on the workshop manual for this model. Not an official publication of the manufacturer.