1982 overcharging

[chasbmw]

I have just taken my bike for the first time in a few months, went to the bath and bristol classic bike show and saw some very nice bikes.

On the way there the bike starting overcharging, anything much over 2000 revs and the voltmeter went to 16+ volts.

I checked with a meter at home and the voltmeter is reading properly. Likely to be faulty regulator? Any other things to check?

Cheers

[barryh]

Sounds like the regulator is faulty.

The regulator switches the rotor current on and off rapidly in order to maintain the correct stator output voltage. When you see voltage go 16+ volts it must be because the switching has stopped and current is being continuously applied to the rotor.

Does the voltage rise gradually ? in which case the regulator isn't switching at all but applying continuous current to the rotor right through the rev range. You can get intermittent faults where the regulator suddenly stops switching and the voltage jumps from normal charge voltage up to as much as 19 volts. Not great for the bulbs or the battery. Either way a new regulator should fix it and you can use any nominal 14 Volt regulator that fits or perhaps an adjustable one.

[SteveD]

I've had that happen once or twice. It was either a dud regulator or the earth was loose.

[chasbmw]

Regulator replaced. Everything ok