Merkblätter zur Restaurierung der überschweren Kräder BMW R75 und Zündapp KS 750.


Herausgeber:  ERSATZTEIL- DIENST   Hans-Peter HOMMES       D-41748   VIERSEN   Tiefenstraße 10       Tel. 02162 - 8100933

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The 6 Volt Generator


H - P Hommes


© 2006 h-p hommes


The 6 Volt Generator (Lichtmaschine)


The ignition system is powered by a Noris or Bosch magneto and does not need any battery power.
The 6 volt generator is only necessary for the lighting system. The sidecar light and the rear light have enough light intensity.
However, many feel the light from the headlamp to be too weak.

With my first bike I felt the light of my headlamp to be too weak. During a trip to Norway through several unlit tunnels I realized that my friend had a much brighter and more intense light than me.
Why was that? There are several factors that optimize a good light

The generator provides a continuous output of 50 watt.


The lighting system requires:          sidecar:                                                      2x 2 Watt=        4 W

                                                     Rear light:                                                         1x3 Watt =      3 W

                                               headlamp                                       1x2 Watt and 1x 25 Watt=     27 W

                                                                                                     total consumption                     34 W  


With 34 Watt consumption we are clearly below the average power output.

The question is why my light getting weaker and weaker on a long drive?

Have the built-in light bulbs the listed wattage or are they bulbs with more consumption?

Has the bulb of the headlamp 25 or 35 watt?

The one of the rear light 3,5 or 10 watt?

If so the generator comes quickly up to its limit.

It may also be noted that the lighting starts being supplied from the generator only from a revolution speed of approx. 1200 to 1500 revolutions of the engine. Up to this speed the battery takes over the power supply.   


What can the battery deliver?

6 volt and 8 ampere give a rating of 48 watt for one hour. Using the wrong bulbs we get a consumption of 51 watt.

So the battery is quickly empty.  

When we continuo at high speed the mathematical result is a deficit because now the battery needs charging current  in addition. 

To make it short the light is getting more and more yellow and weak.

But this is only factor that can create or cause bad light.

The generator and the governor.

At what speeds provides the generator enough electricity to power the light system?

When does the governor switch the automatic cutout with decreasing speed?

If it switches too late, then the battery will discharge through the generator.

How high is the voltage at which the governor limits the electricity?  

Most of the electronic governors have no setting options to adjust the amount of charging current to the existing generator.

 When the clearance between the armature and the pole shoe differs from the standard, the governor must be adjusted accordingly.

This can only be accomplished with individually adjustable governor just as we offer it.


The armature (Order no. 3402-1) and the governor.


Some armatures are milled in a too small diameter. so that the current flow is disturbed.

The outer diameter of the armatures is not always the same so that often a larger clearance is formed between the armature and the pole shoes which also influences the intensity of current.

Differences are also found in the type of windings which also effect the function of the governor.

Another cause for the insufficient power of the generator can be wrong or worn out springs and the coils.

Many small errors lead to the result that there is not enough power supply to operate the lighting system. Last but not least a good quality reflector is necessary to produce a bright light cone. After a systematic overhaul of my generator I got a much brighter and constant light in all speed ranges.

It is now fully sufficient to drive the bike a long time in the dark.

When repairing the generator many of us only make sure that light is produced. But this light is not stable and obtains part of the necessary energy already from the battery.

The light is getting weaker. To get the generator under control quite often the reaction to our own disability is something like this: the 6 volt system is too weak, this was always the problem, we need something else, etc….

The 6 volt system works efficiently when it is properly  repaired.


Then the headlamp has a good bright light that does not collapse even with lower speed.


Wir bieten an:

Ersatzteile + Zubehör + Instandsetzung
für Motor, Getriebe etc. der
Zündapp KS 750 und 600

Wir bieten an:

Ersatzteile + Zubehör + Instandsetzung
für BMW R75 und Zündapp


H-P Hommes Ersatzteil-Dienst
Ersatzteile + Instandsetzungen
repairing + restoring


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