Alternator Problem

[bikerbob]

I have a 1963 A65 about 3 years ago I fitted a new alternator and rotor and everything has been OK since until now. Bike is laid up for winter but I start it up about once a month, yesterday started it up and noticed it was not charging very much, would not hold charge with headlight on, so took the regulator rectifier off and tested it according to what I found on the internet tested ok. Decided to do voltage test on the alternator on tickover only 7 volts coming out increase revs and can get max 10 volts, so looks like I need a new alternator this will be my third alternator in 10 years with a max milage of approx 5000 miles. Bike is converted to 12 volts so has single phase 12 volt alternator fitted is there anything else I could check before I purchase another alternator. Will have to wait until new year before I strip it down.

[DAVE BRADY]

Hi,

What went wrong with the other alternators?  It is unusual for them to go wrong after such low mileage. 

AO Services has a good page about testing alternators.

Dave.

[bikerbob]

Thanks for that, the first alternator the resin cracked for some unknown reason and it allowed the alternator twist slightly and it was catching the rotor with the heat generated by that the resin melted and made a right old mess inside the primary I had to dismantle everything and clean it up the rotor was covered in burnt resin so I purchased a new rotor and alternator and everything has been OK for about 3 years, I had the primary case off last year to check and adjust the primary chain and everything looked OK but now it looks as though I will have to buy my 3rd alternator.

[Ian C]

Assuming the cases are original, it'll just have long studs for stator mounting. Did you check that you had an even gap between rotor and stator all way round?

[bikerbob]

Yes I did make sure that the alternator was not touching the rotor at any poin, I remember that I did have to bend the the studs slightly to achieve this.