yamaha?

U can check the voltage comming out the magnito(alternator)their are 3 wires comming out of the crankcase from the magnito usually 3 yellow wires get a multi-meter and check the voltage comming out remember it is AC (alternating current) comming out and if you rev the bike it should be about 70volts.
the reguletor/rectifier changes this form AC to DC then converts it down to about 14volts. these are the things that pack up on most bikes,not the magnito(alternator).
A quick check is put the multi-meter across the two battery terminals and on a DC voltage setting rev the bike up and the voltage across the battery should go upto 14-15V
hope this is some help

Mr T
May 2008