You just need to break it down into simple steps.
I have pinched this from another forum, and tried to delete the stuff that was specific to the bike they were talking about, hope it helps.
Basically the charging system consists of 3 main components.
Alternator: Which is a generator powered by the engines rotation.
It produces AC voltage by means of magnets in a flywheel and a stator mounted on the casing.
Regulator/ Rectifier: Regulates the voltage so that it stays within a
specific range. Converts AC current to DC current.
Battery: This stores the regulated DC current.
Component location.
Stator: Behind the left hand casing on the engine
Reg/Rec: Right hand side near the water bottle.
Battery: Underneath the rider's seat.
Bike died on you and lights won't work, it won't start or start back up after being used or a dead battery?
If you are experiencing some of those problems then it is possible that part of your charging system has failed, or more specifically the Reg/Rec had failed at some point.
Before starting any of the tests ensure that the battery is fully charged (and reading between 12.8v and 13.2v across the terminals) and that all connectors are clean and tight. The only tools you need are those in your toolkit and a multimeter.
If you have found the battery discharged overnight there are two possible causes.
A voltage leak (something still drawing a current) or a knackered battery (sulphated or damaged cell)
LEAK TEST
Make sure the ignition is switched off and disconnect the earth/ negative (-) lead from the battery.
Connect the multimeter + probe to the earth lead and the "“ probe to the battery terminal. Make sure the meter is reading amps.
With the ignition off there should be no (0) reading unless you have an alarm fitted. The only non switched circuits are the cooling fan and an alarm.
If there is a leakage which exceeds the specified limits. A short circuit or an accessory on is most likely.
The best way to locate the short is to start disconnecting connectors one by one until the culprit is found.
BATTERY TEST
If the leak test is within it specified limits and your battery is still going flat then the battery or a cell in it is suspect.
The only way to do this is to put it on a discharge tester usually only found at your local dealer or bike shop.
DO NOT charge the battery up before taking it to be tested.
CHARGING TEST
Before starting this test warm the engine up to operating temp.
There are several ways of obtaining a reading when checking the charging I will use the simplest one.
Connect the meter and have it set to read volts. Start up the engine and increase the revs to 5,000rpm gradually. Switch on the lights and put Hi beam on.
You should obtain a reading between 13.0v "“ 15.5v @5,000rpm.
If your reading is outwith the above and your battery is fine and all connectors are clean and tight the most likely culprit is the Reg/Rec.
REGULATOR/RECTIFIER
Disconnect the brown plug behind the water bottle and using the meter check the following terminals.
Terminals Reading check
Red/White (+) and earth(frame-) Battery voltage Batt charge
Green and earth Continuity Earth connection
Yellow and Yellow 0.1-1.0 Ohms Charging coil line
Red/white and Green Battery voltage
Yellow and Green There should be NO continuity.
If these check out then the wiring is fine.
REG/REC TESTING
Remove the unit from the bike. The only way to test is to check the resistance between the terminals of the unit
(+) Red/ Yellow Yellow Yellow Green
(-) White 1 2 3
Red/White ------ INF INF INF INF
Yellow 1 0.5-10 ------ 30-500 30-500 10-200
Yellow 2 0.5-10 30-500 ------ 30-500 10-200
Yellow 3 0.5-10 30-500 30-500 ------ 10-200
Green 1-20 0.5-10 0.5-10 0.5-10 --------
The readings are K Ohms.
If any of the readings are outwith the values then replace the REG/REC.
The final test is that of the Charging Coil or Stator.
This has already been done when checking the REG/REC connector. On carbed bikes the connector is in front of the battery below the fuel tank on the others it is behind the battery above the shock mount.
I can see no reason to check this connection other than to rule out a possible short in the wiring harness from this point to the stator/damaged stator, or to eliminate a short in the wiring from the plug to the Reg plug.
The reading should be 0.1-1.0 Ohms between the yellow to yellow terminals.
You should also check each yellow to earth for continuity.
There should be NO continuity.
I hope you find this troubleshooting guide helpful it is made up from my many years working on bikes and from the various manuals that are in print.
Lastly if you are still not sure seek qualified help.
