I was testing the rotor with actual current going through it rather than just a resistance test. The rotor resistance dropped to 3 ohms after the test. Now its changed again. I think Ill just replace it..
R100GSPD Not charging
- Thread starter Wierpig
- Start date
Larry Langford
Registered user
The rotor may act different when it is spinning in the motor as well. Make sure you get the right rotor, it should be 2.8 ohms for a 90's bike. There was a guy selling the earth magnet alternators over in these parts but I haven't checked on that for a spell so I don't know if those can be bought. It would be really trick though as the is no winding there on the rotor just very strong earth magnets. Spin a magnet inside of a coil of wire, the stator, and you get power. On the stock setup the rotor is an electromagnet and does the same thing. Your rotor doesn't look like the epoxy coated newer versions. Looks to be stock from what I can see.
The rotor is a generator, not a load on the circuit. Electrics are very straightforward - you are making it sound complex!
"The rotor may act different when it is spinning in the motor as well" - it is designed to do this.
"Spin a magnet inside of a coil of wire, the stator, and you get power." You actually get voltage. You need to connect another circuit to get power. I think Michael Faraday (English physicist and chemist) found this out on 29 Aug 1831.
I'm going to put a wet towel on my head.
Whilst the theory of electrical circuits may be straightforward, in practice many things can lead you astray from a first time diagnosis. Lack of knowledge of a particular system, incorrect wiring diagrams and ambient conditions.
A poorly or oxidised soldered joint that tests ok with the low current of a multitester, that breaks down with working current. Changes in temperature etc...
A poorly or oxidised soldered joint that tests ok with the low current of a multitester, that breaks down with working current. Changes in temperature etc...
Larry Langford
Registered user
clymer manuals do have good wiring diagrams, if you can figure out which one you need. I wouldn't feel wrong about changing out this rotor, as if you pull one apart and it doesn't have the epoxy, and you can see individual wire of the winding, then you change it out almost automatically ... like a battery that might give you trouble on the road later.
Larry Langford
Registered user
are you one of those ass hurt metzler fans I ruffled up about year ago ..... this comment doesn't deserve a response imo .... absurd
I didn't say it was easy...! But it is straightforward.
The straightforward bit allows you to eliminate components (like the VR) and concentrate on the most likely culprits. If your rotor is changing its resistance then it or the meter is suspect. Can't rule out the multimeter (a dying battery....). Just something to check.
I always turn to Rick Jones's 'Classic Boxer Charging' book to help out. I've quoted from it to help you. I can scan the pages and include them here if you haven't got a copy? That said, as before, if your alternator is only delivering 4VAC per phase then the rotor is not excited enough to deliver more. As the VR checks out, the issue is likely the rotor, or the wiring to it.
At post #16 I tried to help you along the diagnosis path using the facts you had found out and written about.
The straightforward bit allows you to eliminate components (like the VR) and concentrate on the most likely culprits. If your rotor is changing its resistance then it or the meter is suspect. Can't rule out the multimeter (a dying battery....). Just something to check.
I always turn to Rick Jones's 'Classic Boxer Charging' book to help out. I've quoted from it to help you. I can scan the pages and include them here if you haven't got a copy? That said, as before, if your alternator is only delivering 4VAC per phase then the rotor is not excited enough to deliver more. As the VR checks out, the issue is likely the rotor, or the wiring to it.
I tested the multimeter using a new 9v battery and a 5k ohm resistor. All good. I appreciate your input. Ill oder a new rotor tomorrow and report back...
Are the Motorworks pattern rotors any good? Ive ordered a copy of the electrics bible!
Are the Motorworks pattern rotors any good? Ive ordered a copy of the electrics bible!
Reading their description of the reconditioned secondhand ones, they sound pretty good. I've never needed to buy one as I still have a few spare alternators on the shelf to get through before I do..
I bought an uprated alternator (600W?) off Bob Porecha a while back for my RS for a trip to Spain. I think that's the only one I've bought off a shop. Rest came from secondhand spares buys, where you find one at the bottom of a box of other stuff. They have all checked out though. And I don't think I needed 600W!
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