Alternators
The Alternator first appeared on British motorcycles in the mid 1950s. The original alternator stators (open windings type) were prone to problems with vibration shaking the windings loose. The remedy for this was to encapsulate the windings in resin, all new stators are of this type.
By the 1960s LUCAS has standardised the sizes of the alternators and by the mid 1960s the alternators were being produced in 12v form (LUCAS RM21).
The introduction of the three phase stator pushed the alternator output up from 120 to 180 Watts whilst still retaining the same magnetic rotor but with Three Phase windings.
ALTERNATOR TYPES
LU47204 6 VOLT 3 wire 120 Watt Single phase.
Direct replacement for early 6V open windings type, to be used if the original 6 volt system is to be retained. A 12V conversion using LU47205 is a common modification.
Uses Standard LU54202299 magnetic Rotor.
LU47205 12 VOLT 2 wire 120 Watts Single phase.
This is the most common stator winding used on British bikes from the mid 1960s to the late 1970s. The original rectifier and Zenor diode arrangement is best replaced with a modern Single phase rectifier regulator box such as the Podtronic-1.
Uses Standard LU54202299 magnetic Rotor.
LU47244 12 VOLT 3 wire 180 Watt Three phase.
This is a very popular and reliable upgrade of the electrical system. It can replace all above stator windings, not only producing more Maximium power but also producing more power in the lower rev range. The Zenor diode and rectifier must be replaced with a Three phase regulator rectifier box such as Podtronic-2.
Using Standard LU54202299 magnetic Rotor.
Alternator Problems
- Windings in poor condition or output wires broken or damaged.
- If the Rotor is touching the inside of stator it will cause overheating and loss of electrical power.
- Magnetic strength of rotor is low (usually due age) causing reduced power output.
- When checking the alternator, measure voltages between the alternator wires (not to earth) using the AC voltage range.
Printer-friendly version