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Testing alternator

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Jimbo550:
I have an electrical problem which I think could lead to the alternator but electrics isn't my strong point so I,m looking for some help.  I've checked across the battery terminals with the bike running and I can only get 11.5 volts max at 4000rpm.  I then disconnected the plug which come from the alternator into the left side casing with the 3 yellow wires.  I put the multimeter on ac voltage and while the bike was running I tested each yellow wire with + terminal while - terminal was to earth. I don't get any readings. Am I testing this correctly? If so does this mean my alternator is duff.

Jimbo550:
Correction. I wasn't testing it correctly. I've tested pairs of yellow wires and only seem to be getting 1.5v ac when revving it to 4000rpm. I'm thinking this is duff and need to be rewound. What voltages should I expect?

Bryanj:
You will only get AC out if DC is going into the field coil on the green and white wires

Jimbo550:
Ok thanks Bryan. Electrics I really have problems understanding. I have tested again with a dc supply going in and seem to be getting different figures. 10v, 15v, 2vac. What should I expect to get?

Bryanj:
From memory 40-50Vac between each pair, I would remove the  cover and check the connections

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