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| Jabberwock |
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Jabberwock
L Plate Warrior
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| Howling Terror |
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Howling Terror
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 Posted: 21:59 - 07 Jul 2017  Post subject: |
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Checking the regulator/rectifier is usually the first place to check. Open the plastic connector and see if it looks burned. Next thing is to hook up a multimeter to the battery and see if the voltage rises to approx 14volts when the engine is revved.
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| stinkwheel |
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stinkwheel
Bovine Proctologist
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| Posted: 10:52 - 08 Jul 2017 Post subject: |
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All of these things can be simply tested with a multimeter.
The tests work best with a charged battery. So charge the battery, get a multimeter.
As HT says, your first test is voltage across the battery with the engine off, the engine on and the engine being revved. (should be 12-ish, 13-ish and 14.5-ish respectively).
Another possability is a partial or intermittant short circuit draining the power.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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| Jabberwock |
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Jabberwock
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| The Shaggy D.A. |
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The Shaggy D.A.
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| Jabberwock |
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Jabberwock
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| Jabberwock |
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Jabberwock
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| stinkwheel |
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stinkwheel
Bovine Proctologist
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Posted: 11:38 - 10 Jul 2017  Post subject: |
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| Jabberwock wrote: | So the battery shows 12.32,and doesn't alter when engine is revved,Does this mean the rectifier is u/s? |
It means the battery isn't charging. So we're looking at either the reg/rec, the alternator or the connections between them.
Reg/recs are tricky to test without specialist equipment so best bet is to eliminate other possabilities. If it's not them, then it's the reg/rec. Your particular type of charging system should be less prone to failure than most though. Most likely suspect for yours is the alternator rotor (this can also damage the reg/rec if it fails).
So first find the reg/rec. Looking at your wiring, it has two connectors. One has three yellows, a black and a white. The other has a black, a green and a white on red.
With the engine off, unplug the one with the yellows, these readings will be done on the connector attached to the bike, not the reg/rec. Set your meter to measure resistance. Test between each pair of yellow wires, they should have an equal and fairly low resistance. If they have a high resistance (same reading as with the probes apart), there is a problem.
Now test between each yellow and earth (either bare metal on the engine or the battery negative). There should be high resistance. A low reading means there is a short in the windings.
Now. Your bike is a little oddball compared to most japanese bikes. It has a field coil alternator (which has electromagnets and carbon brushes instead of permanant magnets). We may need to come back to these but test the resistance between the black and the white wire. There should be a low reading. Should be between 2-5 ohms according to google. A very high reading is a problem as is anything less than 2 ohms.
Now set your meter to read volts DC. Measure again between the black and white wires but this time on the connector attached to the reg/rec with the ignition ON. You should get a voltage reading (not sure what, probably battery volts).
Now move onto the other connector. Again on the side attached to the bike you should get battery voltage between the white/red and the green wire at all times. You should get battery voltage between the green and the black wire only when the ignition is on.
If all of the above checks out, you've pretty much eliminated a short/break in the alternator windings and confirmed the wiring is intact.
Now, those carbon brushes which most bikes don't have. They run on two circular copper tracks on the alternator rotor (the part that spins) to provide power to the electromagnets. They are wearable componants, they are also 34 years old and made of graphite. The resistance test between the black and the white wire tells you that they are making contact (high resistance = no contact), it doesn't tell you they're making good contact when it's moving. They might need a visual inspection to check they are within wear limits (there is a wear line on them).
The rotor itself also has coils in it which can go south. A very low resistance (<2 ohm) would be a bad sign.
That's probably enough for now huh? There are dynamic tests you can do too but a note of caution. These alternators can pack a punch if they regulator is faulty so take care if doing tests on it with the engine running.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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| Jabberwock |
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Jabberwock
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| Posted: 13:11 - 10 Jul 2017 Post subject: 1983 nighthawk |
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Wow.Pretty comprehensive-thank you so much. It's going to take me a while to unravel it with my skills, but that will be a learning experience I badly need-so thank you very much indeed. I have had a quote of £160 for a rectifier, so knowing whether it's working or not is pretty important....as for rotor, don't like to think about it.
Many thanks again for taking so much trouble. 
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| stinkwheel |
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stinkwheel
Bovine Proctologist
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Old Thread Alert!
The last post was made 6 years, 285 days ago. Instead of replying here, would creating a new thread be more useful? |
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