Stator testing

[briancairns]

Hi
Looking for advice on testing my stator ( RM19 , I think).
It is actually of a 1959 Matchless single G3 with a coil ignition ( 6V) however I am a BSA Club member with a BSA B31.
I am not getting any charge across the battery whatsoever, I am using a bridge rectifier ( which is testing perfectly).
I bought the bike in this condition ( price altered accordingly).
Bike has a new wiring loom.
With the results below should I be getting some charge across the battery? I think the bike has been wired incorrectly.
Are there anymore tests I could run?
The stator is a single phase with 3 wires :
BG Black/Green
GY Green/yellow
WG White/black.

I am getting the following resistance ( ohms) and AC voltage between wires:

BG to GY; 1.2 ohms and 4.0 ac volts at idle and 9.0 at 3000rpm
BG to WG : 0.8 ohms and 26.4 ac volts at idle and 70.0 at 3000rpm
GY to WG: 0.3 ohms and 26.6 ac volts at idle and 64.0 at 3000rpm.

I also checked for any grounding, all is fine.

Thanks in advance
Brian

[rhyatt]

Pick any pair of wires , get a headlamp bulb and connect across this stator pair.
Do this on all 3 pairs
Should light the bulb , don't rev too much

[scifi]

Hi Brian, if you are using a digital multimeter, are you sure you have the decimal place correct.   70v ac seems to be way too much for a 6 volt battery.   If it is 7.0v rms that would give a peak voltage to the diode pack of about 10 volts.  That would drop when the battery takes some charging current.

[briancairns]

Pick any pair of wires , get a headlamp bulb and connect across this stator pair.
Do this on all 3 pairs
Should light the bulb , don't rev too much

Thanks will try that

[briancairns]

Hi Brian, if you are using a digital multimeter, are you sure you have the decimal place correct.   70v ac seems to be way too much for a 6 volt battery.   If it is 7.0v rms that would give a peak voltage to the diode pack of about 10 volts.  That would drop when the battery takes some charging current.

Will check again but 99.9% sure readings are correct.
I am trying to figure out if the stator is bad or some other wiring problem
Cheers

[Rog1]

I presume you tested the bridge rectifier with a resistance meter. Now check the output at the bridge rectifier; if all is well then trace the wires to the battery and see if they go to the right places. I found a G3L wiring diagram online and there are wires going to the ignition and lighting switches; lots of scope to put wires in the wrong terminals!

If the output is low or non existent first check the input to the rectifier, as close to it as you can get. See if it matches your previous readings from the stator.

[briancairns]

I presume you tested the bridge rectifier with a resistance meter. Now check the output at the bridge rectifier; if all is well then trace the wires to the battery and see if they go to the right places. I found a G3L wiring diagram online and there are wires going to the ignition and lighting switches; lots of scope to put wires in the wrong terminals!

If the output is low or non existent first check the input to the rectifier, as close to it as you can get. See if it matches your previous readings from the stator.

Great advice
I checked bridge rectifier with diode setting on multimeter...all good.I have spare bridge rectifier and all give the same readings etc
Will check this tomorrow and let group know.
I was just thinking about checking output at rectifier.But think problem ( as you indicated )is at the ignition/lighting end

Thanks

Brian

[briancairns]

Hi Brian, if you are using a digital multimeter, are you sure you have the decimal place correct.  70v ac seems to be way too much for a 6 volt battery.  If it is 7.0v rms that would give a peak voltage to the diode pack of about 10 volts.  That would drop when the battery takes some charging current.

Will check again but 99.9% sure readings are correct.
I am trying to figure out if the stator is bad or some other wiring problem
Cheers

Hi Checked ac votlage again....all as stated.
According to anything i have seen on-line the voltages I quoted are correct except the BG to GY; 1.2 ohms and 4.0 ac volts at idle and 9.0 at 3000rpm which should read roughly like the others
Thanks
Brian

[briancairns]

Pick any pair of wires , get a headlamp bulb and connect across this stator pair.
Do this on all 3 pairs
Should light the bulb , don't rev too much

Thanks will try that

Hi , I tried the bulb test;
BG to GY; 1.2 ohms and 4.0 ac volts at idle and 9.0 at 3000rpm. No light on blub test
BG to WG : 0.8 ohms and 26.4 ac volts at idle and 70.0 at 3000rpm. Bulb test postive, lights up brightly
GY to WG: 0.3 ohms and 26.6 ac volts at idle and 64.0 at 3000rpm. Bulb test postive, lights up brightly

looks like stator may be gone?

Cheers
Brian

[briancairns]

Hi
Looking for advice on testing my stator ( RM19 , I think).
It is actually of a 1959 Matchless single G3 with a coil ignition ( 6V) however I am a BSA Club member with a BSA B31.
I am not getting any charge across the battery whatsoever, I am using a bridge rectifier ( which is testing perfectly).
I bought the bike in this condition ( price altered accordingly).
Bike has a new wiring loom.
With the results below should I be getting some charge across the battery? I think the bike has been wired incorrectly.
Are there anymore tests I could run?
The stator is a single phase with 3 wires :
BG Black/Green
GY Green/yellow
WG White/black.

I am getting the following resistance ( ohms) and AC voltage between wires:

BG to GY; 1.2 ohms and 4.0 ac volts at idle and 9.0 at 3000rpm
BG to WG : 0.8 ohms and 26.4 ac volts at idle and 70.0 at 3000rpm
GY to WG: 0.3 ohms and 26.6 ac volts at idle and 64.0 at 3000rpm.

I also checked for any grounding, all is fine.

Thanks in advance
Brian


Also,
When I start bike, unhook battery, and measure DC voltage across battery wires I am getting 64 DC volts?
But when battery is hooked up I am getting nothing? I wonder is stator wired up for 12v system?
I am totally confused.

Brian

[rhyatt]

Pick any pair of wires , get a headlamp bulb and connect across this stator pair.
Do this on all 3 pairs
Should light the bulb , don't rev too much

Thanks will try that

Hi , I tried the bulb test;
BG to GY;  No light on blub test
BG to WG :  Bulb test postive, lights up brightly
GY to WG:  Bulb test postive, lights up brightly

looks like stator may be gone?

Yes indeed
Same as my c15 had with charging issues.
Spent 95 quid on a brand new lucas /wassell 12v , 2 wire alternator, changed the coil and bulbs, all done

[scifi]

I was thinking your 70 volts was somehow incorrect, but after seeing this video, it indicates your BG-GY is faulty and should also be 70v.

https://www.youtube.com/watch?v=qqSZWaWEe3s

New stators are available, and all leads should give identical voltages.  ( Fecked do them.)

[V500]

Avoid Feked like the plague. No customer returns even if faulty.

[rhyatt]

I have always , always , centralised my bsa purchases with Kidderminster motorcycle.
Sensible help , willing knowledge.

[briancairns]

Avoid Feked like the plague. No customer returns even if faulty.

Yes had a few issues with them previously.

Thanks all for your help.

Brian