Charging - Low rotor resistance but charging

[madoc]

My rotor has about 3ohm between the rings (should be around 5.3).
I have been experiencing a few of , what I thought were, regulator issues (as jumping the green wire solved them) and a new electrosport regulator doesn't work at all.

Funny thing is that the rotor passes the slap test and puts out over 14v, just off idle, without lights, It needs maybe 3k revs to get to 13.5v with the lights though.

New brushes BTW.
Didn't affect anything really ..

Is the definitely the rotor at fault ?
Are there any other tests I can do to check ..

If it is, then it's the worst possible result really as these are not too available in the UK and it's a 1980 SE bike, running a standard setup.

 

[nj1639]

I've been running a rebuilt rotor for six plus years now, ohmed out at around 4 ohms from the rebuild. Charges around 13.75 on throttle, lights on and never exceeds 14 volts. Not sure of the implications. I believe that I read that some of the rebuilt rotors ohm a bit shy of 5 and iirc it may have something to do with the newer wire windings. So far, so good.
If I'm fekked I don't know it.

 

[madoc]

My problem only came to light when the charging stopped one evening. Once I jumped the green wire, then it's worked since. I did add a direct earth from the reg black wire..

I ain't got no problem riding it about and waiting for failure BUT .. if the charging goes, 30 miles from home on a dark night then I'm fecked too (and there ain't no mobile signals around here ...). This time of year the nights are getting darker too ....

 

[XSLeo]

The low ohms is the reason for the low output.
The resistance measures the length of the electrical path through the rotor. This length of electrical path is what determines the strength of the magnetism. With low ohms this means the insulation on the wire is breaking down. This lets electricity leak out, weakening the magnetism. The weaker the magnetism the less the output.
A rotor has a winding, this winding has somewhere around 325 feet of wire. This length of wire has a certain amount of ohms. When rewound with new wire they can't get quite as much wire on the rotor. This gives you the slightly less ohms. Even with a bit less ohms you will still get good output.
Heiden Tuning list one for the 80 up bikes for 135,00 Euro's. This has the magnet for the TCI. They list the 70-79 rotor without the magnet for Euro's 130,00.
You might find a local place that works on car starters and alternators that can rewind your stator.
Leo

 

[DIRTY DOG]

my rebuilt one was 4.5 he said they charge better and last longer that way charges 13.7
at Idle with head leight on low and led tail light go up to 14.2 over 2500 rpm had it done about 3 years ago

 

[madoc]

Ok.
So I am hearing that low resistance is indicative of failing wiring and it's just going to get worse....I guess the hunt is on for another standard rotor.

The Permanent Magnet thing, for later bikes, requires a new ignition system to go with it. That's not trivial pennies ....

 

[XSLeo]

I assume the bike you are talking about is the 80 XS650G in your signature. Does it use points or the TCI. If points then you need the 70-79 rotor. If it uses the TCI you need an 80 up rotor.
Leo