Boxerworks.com

I can't seem to find the answer to this one searching the messages!

My R90s 1973 has over the last month or so started to indicate a voltage of 16+ volts at 3000rpm - It doesn't get much higher with more revs and does drop to about 14.5 at tickover. Headlight on makes little difference. It measures just about the same at the battery with a voltmeter. Certainly too high for the Gel Battery and too much for the headlight wiring which I have just replaced as the insulation was melting!
All works wonderfully at the moment but I sense disaster is not too distant!

Is this just a case of changing the Voltage regulator or is there some other gremlin in the machine that has been discovered by someone with a little more electrical knowledge than I have?

Many thanks for any ideas.

Sounds like the regulator to me.

Thank you - I have heard of regulators giving too low a voltage - I couldn't find any message where the voltage had increased.

If yours is original it will be the electro/mechanical type of voltage regulator and I have seen those fail high. They are serviceable to a degree and can be adjusted but it's not that easy and you might want to replace it with an electronic type.

It can't really be anything else as the only thing that will cause a high charging voltage is too much current through the rotor and only the regulator or short circuit wiring from the regulator can do that.

Thanks Barry - nice to hear from someone in the County of Cheshire - I see Motorworks do an electronic regulator (Voltage regulator electronic standard output) so I'll give them a ring tomorrow. Probably a good update anyway as the old one is original and 40+ years old.

Bosche RE 57 seems plentiful in Australia - anyone know a UK distributor?....I can't locate one on the web although plenty in Europe and the USA.

Found one in Birmingham UK!
Vehicle Electrics UK have this:-
VERG1058 EXTERNAL VOLTAGE REGULATOR BOSCH VALEO 12V VOLT BMW FORD MERCEDES VOLVO
replaces the original Bosch yellow taped regulator (which is numbered 0190601009 on mine)
£10.50 plus VAT and free delivery - (they sell the same regulator for more on eBay)

but couldn't place the RE57 reference - must be used outside UK

Thanks everyone

SteveD wrote:Bosch RE57 from your local auto shop does the job. It might be cheaper and more widely available.

Does a re57 suit the older bikes like /6

re57 has 3 pins and I think a 74 has two pins?
I might be dreaming.

The original 40 year old yellow taped voltage regulator was still on my bike and the part number is 0190601009. The BOSCH VALEO lists this number in the Vehicle Electrics site (and about 30 more) as the replacement. The fixing holes are 40mm (as old regulator) and the pins are in a triangular configuration so will probably fit the existing regulator plug.
We'll see!
Best wishes