Join Date: Aug 2013
I Ride: 1987 GSX-R 250, 1998 ZX6R.
Your charging system is kaput. As already stated, it could be: Fixed magnet/rotor (they don't like sharp impacts, like being dropped. It weakens them which means a weak charging system), Stator, or rectifier/voltage regulator assembly.
To diagnose which, pull off what you need to in order to expose the plug coming out of the generator cover. There will be three wires. Test the resistance between each with a multimeter. You should have in the neighbourhood of 0.35 ohms between each. Also check resistance between the chassis ground and each of the three wires. It should be infinite. If any reading differs significantly from the other two, or conducts to ground, your stator is bad. If the alternator is putting out significantly less than 40 Volts AC (@ 4,000 rpm) for each phase of the alternator and the stator resistances are good, you most likely have a weak magnet/rotor. If both rotor and stator check out and open circuit voltage is good, you most likely have a bad rectifier/regulator assembly.
These values are approximate, each bike may well differ slightly. However, each phase of the alternator should be similar to the other two. If not, there is cause for suspicion... Also, it should go without saying, but check all connections between the stator windings, rectifier/regulator and battery before replacing or testing anything else.
Last edited by Dennymambo; 09-07-2013 at 05:40 AM.
Reason: Bad memory...