Using Multimeter to Test Alternator. Dead or Not?

Ok so thx to you guys that have been helping me with these electrical issues. so my starter was totally dead i have ordered a new one which is coming this week but even with push starting my bike the voltage keeps going down so i'm wondering if it isn't charging. I read in my service manual how to test the charging system and it was supposed to be around 14.2-14.8 at 2000 rpm but it was only 12.6. So i proceeded to test the 2 pin and 3 pin connectors for ohm resistance which i have no idea if i'm doing it right. So i turned the key on and the engine killswitch to run and tested the 2 pin and got anywhere from 0.3-0.5 ( was supposed to be 3.6-4.2) and on the 3 pin i got infinite, infinite, and 0.6. The book says this should mean the alternator is dead but i don't know if i tested right or anything having never done this before. Input or suggestions would be awesome thx!!

 

The main problems on these bikes will be loose, corroded or burnt connections at the wiring connector from the alternator or bad brushes and gunked up contact rings on the rotor. So if the connectors are ok, you'll need to open the alternator.

 

key OFF, both plugs apart. clip your leads together, don't touch them, get a reading for just the leads, write it down.and subtract it from all your other readings. white plug needs 2 tests, clip on a connector and leave it there and measure to the 2 other connectors, you need a good connection and you can only touch 1 lead (or you'll be measuring your hand).
same with to 2 pin, only touch 1 lead, good connection, subtract

 

Ok i will retest and post results

 

K so the things themselves were .5 the 3 prong were both 7 minus the .5 so 6.5 and the 2 prong was .5 so nothing after subtraction so does that mean the alternator is dead or do I need to test the regulator/rectifier?

 

for now lets call it good, before you go any farther check the alternator brushes. take the cover off the alternator, 3 screws and it will still be attached with wires, carefully swing it out so you can see the brushes, try not to pull the wires out of the rubber grommet. they can be a pain to get back in. the brushes have a line on them, if your getting within 1/8 inch of the line that could be the whole problem. at 1/8 inch i'd replace them. check that the brushes are springy and shine up the 2 copper rings on the rotor with a ink pen eraser. then either get brushes or put it all back and test voltage again

 

ok i will try that over the next couple of days.

 

Ok got this alternator all pulled apart. I'll post some pics in here too but the brushes were well above the wear indicator and looked ok however the winding i think it's called is all coated in black grease which i think is the problem, if so how do i clean it etc?

 

here's the pics

 

Do not use a flammable cleaner or you'll create a grenade. The windings is called a stator. After cleaning, check the windings for signs of burning (dark and discolored wire) and bare spots in the insulation. The insulation is a enamel coating on the wire itself that insulates the phases from each other and plastic inserts that insulate the windings from the base. If all looks well then the stator is probably ok, the only way to be sure is to take the stator to a automotive electric shop and have them test it.
Did you check the connections on the alternator wires(output wires)?

 

So I cleaned everything and still nothing. So on the 2 prong clip with the bike on the battery is sending like 10 v but nothing is coming back. I wanted to test my regulator cuz it looks like it passes thru that but if my ohms are still nothing on the 2 prong is the wire most likely dead?

 

Just looked at the stator looks like its slightly burned but I'm not sure its like dark reddish also looked like a few very thin spots if not bare wire on the insulation

 

The 2 prong connector is power and ground(supplied thru regulator) to activate the brushes. The three prong connector from the stator delivers AC power to the rectifier which converts to DC to charge the battery. So you'll want to concentrate on the three prong from the stator. If the connections are good, you should be reading AC volts/amps while charging.

 

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

 

Ok so i did this electronic fault test adrian1 suggested and found that my rotor had 0 ohm resistance so it is dead and i found a used one on ebay which should come this week what i need to know is how can i change out the rotor without a special tool? And is there anything i need to be sure to do or not do?

 

You will need a special puller bolt to remove the rotor. Don't remember the exact size but you won't find one at a hardware store. From the looks of it I would say that the oil seal is leaking. Since the rotor is being pulled go ahead and replace the seal and o-ring in the there. Most likley you will tear the retaining screws uo trying to get them out so get some of them also. A impact screwdriver is a must have tool to remove those screws. They have loctite holding them in.

 

ok so what exactly is the process of changing it and where could i find the tool? Also do you know how much approx it would cost? Thx

 

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