charging system testing

as these bikes have been around for 30 years i'm guessing this question has been answered but i'm not sure where to find it in the forums. i have the clymer repair manual and have done some preliminary testing of the charging system. as i revved the rpm up to above 2500 and was getting a steady 12 volts. there were a few moments where the voltage jumped well above that, not sure how that happened. then did some testing on the wiring for the voltage regulator as well as the rotor and stater. this is my first time testing electrical so i feel a little lost with the results. i would really love it if i did not need to open the bike's guts to replace brushes and things but that's where this is sounding i will need to go. any suggestions?

 

When you measure voltage across battery terminals, at +2500rpm you should read approx 14.5V.

check all terminals and connectors to ensure clean and regrease as neccessary.

Over 15V or below 12 suspect Reg/Rec use your manual to test, somewhere on the site is a crib sheet, if i can find it I will post you a link.

if you can source a colour coded wiring diagram it helps!

once you start pulling the covers, with help on this site you should have no worries about learning how to..good luck.

 

How many miles on this particular 550?

You should be seeing 14.5 ~ 14.7VDC at 2500RPM.

Start by checking the condition of the terminals in the big white connector coming off the rec/reg assembly;

and based on mileage, it could very well be time for new alternator brushes. They're mounted in the alternator cover, it's not a difficult procedure.

But knowing these bikes as I do, I'd start by "wringing out" the wiring.

 

http://www.electrosport.com/media/pdf/f ... iagram.pdf

 

Soccersquash,

big guns have come to your rescue!

you will be led by the hand all the way through. enjoy your 1st foray into the xj's electrics.

 

there are a little over 40k miles on this bike.
i only have 1 multi meter at the moment so i was unable to test the voltage
regulator, clymer calls for 2 meters. the ohm reading's were a little higher
than what clymer said they should be but the one reading that disturbed me
was the reading for the rotor. i should have had a reading of around 4.5
ohms but am getting an infinite reading.

 

What do the brushes themselves look like?

The originals have "wear limit lines" in the brushes, if you can't see the lines they're worn past the limit.

Another thing to check is the little, fine braided lead wires to the brushes themselves. They tend to get all green and corroded inside the braiding.

It's hard to get good readings off the rotor (hard to make good contact.) If the alternator had any output at all, I doubt the rotor is truly "open."

 

this is a great place to start, lots of info