1933 Blue star electric system

timbo · 25 November, 2020, 13:44:36

After searching and collecting the electrical bits for my Blue star for some years now I
am almost there. Now I was reading about how this system works and it seems I am still missing
a part. They speak about a resistor to control the charge wit the knob on the instrument panel.
I dont have one of these. How does this look like? could a modern resistor be used? What is the value of the resistance and its wattage?

regards

Tim

Y13 Alan G · 25 November, 2020, 14:47:01

Hi Tim, What year is your Blue Star? I may be able to help when I know this. Also does your bike have a triangular instrument panel in the centre of the fuel tank, if not where is it?

Y13 Alan G · 25 November, 2020, 14:54:08

Hi Tim, I forgot to ask do you have a 2 brush or 3 brush dynamo?

timbo · 25 November, 2020, 15:24:31

I think it is a 1933 Blue Star. I have a triangular instrument pannel on the fuel tank and a
3 brush dynamo.

Y13 Alan G · 25 November, 2020, 16:56:51

Hi Tim,
With a 3 brush dynamo the switch has 4 positions, "Off", "CH or T", "L" & "H". The purpose of the resistor is to reduce the charge when the switch is in the "T,CH" or "L" position. The full charge only occurs when the headlights are on. Original resistors are unobtainable. However, how often are you going to use the bike with the the switch in the "Charge" or "sidelight" position. I have the same system on my 1932 G32/12 and I find that a fully charged battery will last for several VMCC runs as I only need it for the horn. No brake light as not originally fitted and not required by law for m/cycles made before 31st March 1935. So without the resistor wire the switch so that the dynamo only charges when in the "L" & "H" positions.
Im attaching two photos, one of the switch & a wiring diagram. If the files are too big I'll send another post.

timbo · 25 November, 2020, 17:04:00

Hey,never tought of it that way. I just wanted to complete the system.
I was not hoping to find a original resistance,but tought a more modern alternative would
do the job. I would have to check but here in belgium normaly motorcycles must drive day and night
with the lights on. I don't know for the vintage bikes.

Y13 Alan G · 25 November, 2020, 17:15:09

Hi Tim, photo of switch & wiring diagram attached. If you have to drive with lights on in Belgium then why not convert your 3 brush dynamo to 2 brush and fit a modern voltage control unit. A word of caution from bitter experience if you fit a modern voltage control unit make sure it is well ventilated and has a good heat sink otherwise it will overheat and burn out. There are instructions how to do this on the internet. Best of luck Alan

Y13 Alan G · 25 November, 2020, 17:20:00

Wiring diagram

timbo · 25 November, 2020, 18:03:13

Thanks for the picture. I have the correct switch but the resistor is not there.
Is this a whole unit with the switch or can you take it of the switch?
Maybe I schould convert.

timbo · 25 November, 2020, 21:30:19

This is my switch,looks different from yours

timbo · 25 November, 2020, 21:31:31

switch

timbo · 25 November, 2020, 21:32:36

pannel

Y13 Alan G · 26 November, 2020, 13:35:16

Ok, your switch is for a 2 brush dynamo. So you can either convert your 3 brush dynamo to 2 brush, see internet, or only use the three brush with the lights on, not in the "Charge" position. Regards Alan

timbo · 26 November, 2020, 15:14:50

Ok,i did not know that. I tought it was for the three brush system because there are the C H and L positions.

Group Leader · 29 November, 2020, 18:43:10

I'd go for the 2 brush conversion and the addition of a modern DVR2 electronic regulator. All modern electronic regulators are not equal ....

By the way, the DVR2 is a very compact device and could be hidden somewhere about the bike. In my case on a '39 B21 I think it would have had a Lucas regulator so mine is lurking inside the Lucas reg case.

Alan (no connection with the manufacturers of DVR2s just a happy customer)