BGM stator query

[TS1-200]

Ordered & received a BGM stator, ony I have been sent 120w DC stator, rather than mess about sending it back, can this be used as an AC stator, just ignoring the extra wires, as its really a spare for my AC wired GP

[MickYork]

Copied from MB site:

Electronic ignition stator plate 12 volt DC, BGM


BGM's new 12 Volt DC stator plate.

The ultimate Lambretta Stator plate to give the most power to run the lighting system on DC using a capacitor or battery.

Works with our BGM Rectifier or any single phase rectifiers (Wassell/Podtronics)

This stator can also be used as an AC stator by using one of the 2 Yellow wires as earth. If it doesn't work swap one of the Yellow wires around

[rossclark]

It shouldn't matter which yellow you connect to earth since they're each at one end of the coils.

[TS1-200]

Thats handy as it does give the option of going DC at a later date if required, electrics are a bit of a black art to me.

[Nelly]

Copied from MB site:

This stator can also be used as an AC stator by using one of the 2 Yellow wires as earth. If it doesn't work swap one of the Yellow wires around

That statement is a little misleading.
You need to earth one of the yellow wires to a common earthed point, ie frame, not use it as earth. This then ties one end of the lighting coils down to earth, the same as how a normal ac stator is wired.
I would also take the engine earth from this earthing point too, this will ensure everything is at the same potential.
At a later date it will be very easy to convert to DC by simply disconnecting the yellow that was earthed and connecting the 2 yellows into the Wassel rectifier. best of both worlds!

[Eden]

Can I jump on this topic and also ask a question regarding BGM stators??????


I had to fit one to someone's motor a few weeks back and as it was the first one I had seen I decided to take a few measurements, I did so due to all the talk about BGM stators/flywheels giving problems when mixed and matched with other makes. I found that the Pickup sits around 2mm lower on the plate than on an original/Indian stator and wondered why this was the case. Has anyone else noticed this? Are the triggers on a BGM flywheel longer than on an original flywheel?

[Adam_Winstone]

^... should probably read 'lower', rather than 'longer'.

No idea about the BGM flywheel but the difference in pickup height is not new, with me previously finding that I needed to use flat washers under BGM stators to get a clean spark on some SIL flywheels and on the couple of Indian light AF flywheels that I've been asked to help mates with. The washers under the stator raise it to match the height of the standard SIL stator.

The 2 yellow design is nothing new, this is what the Spanish did on their later stators, with you taking one to earth for AC systems or both to a rectifier for DC. It is a good idea and it gives you the chance to change your mind at any stage, without needing to remove flywheel or stator.

Adam

[MK Monty]

Yes I found the same, when I was chasing my wandering firing point. I was unsure at the time that the pickup lined up with the join in the magnates, so did a lot of measuring of 3 different stators and my flywheel with and without the woodruff key even lapping the wheel and crank. The BGM was 2 mm lower than all my other stators. But the indian ones did not line up with the pickup. another 2 mm would bring it so the join in the magnet was between the two steel strips on the pickup? I removed the pickup and made a spacer to lift it up. It could have gone further but I would have lost the pin registration and I didn't want to go too high in case it hit the flywheel. Did it solve my problem NO I think it was the BGM CDI that made the big difference, My others were Indian and Jap. Still running with the spacer.

[Eden]

I wonder why they lowered the pickup

[dscscotty]

The last batch I've seen seem to have had to much machined from the back of plate. If you look it looks like they've been over done and as a result the stator sits lower in the mag house, great if your using original AF Ducati flywheel.
I to on several occasions have had to pack up/space the stator to hit the trigger point on the flywheel.

[TS1-200]

OK to recap, one of the yellow wires, goes straight to an earthing point, not to the regulator, and the white, red, green, go to the CD1, so what wire goes to the regulator, the other yellow ? how can you tell which yellow goes where

[Nelly]

OK to recap, one of the yellow wires, goes straight to an earthing point, not to the regulator, and the white, red, green, go to the CD1, so what wire goes to the regulator, the other yellow ? how can you tell which yellow goes where

Yep, the other yellow goes to the regulator.
It doesn't matter which yellow you choose to take to which point, they are just the end of the coils, like a big loop of string, technically.

[Nelly]

Here's 2 pics from a tutorial on how to convert a standard stator to DC.
See how they de-solder the end of the coils from the earthed point on the stator plate and attach a new yellow wire to it? This is basically how your stator plate is wired, like the modified one.
All you are doing to return it to the original configuration is to earth one end of the coils again.
As you can see in the pic, it won't matter which one goes down to earth, it's just a big loop of wire going round the coils.
I could go into detail and explain exactly how it works when running, but that would just bore the crap out of you............

[TS1-200]

Thanks all, I`m clear now.

[HxPaul]

Here's 2 pics from a tutorial on how to convert a standard stator to DC.
See how they de-solder the end of the coils from the earthed point on the stator plate and attach a new yellow wire to it? This is basically how your stator plate is wired, like the modified one.
All you are doing to return it to the original configuration is to earth one end of the coils again.
As you can see in the pic, it won't matter which one goes down to earth, it's just a big loop of wire going round the coils.
I could go into detail and explain exactly how it works when running, but that would just bore the crap out of you............

Just as a matter of interest,how do you check the resistance measurement of the lighting coils with a multi-meter and what should the reading be.

[Nelly]

The lighting coils are a very low resistance, hardly even registering a resistance on the multimeter, due to the wire used in the lighting coils being heavier gauge than that used in the low tension coil and pickup coil.
To test you have continuity set the meter to the lowest ohms scale and test across all the coils.
I'll double check in the Vespa Haynes manual if there was a benchmark resistance to look for across the lighting coils, I really can't remember. It would be very low resistance though.
Hope this helps.

[coaster]

The lighting coils are a very low resistance, hardly even registering a resistance on the multimeter, due to the wire used in the lighting coils being heavier gauge than that used in the low tension coil and pickup coil.
To test you have continuity set the meter to the lowest ohms scale and test across all the coils.
I'll double check in the Vespa Haynes manual if there was a benchmark resistance to look for across the lighting coils, I really can't remember. It would be very low resistance though.
Hope this helps.

I agree, I'd be interested if there is a benchmark reading but even if there is, it'll be in the order of 1 ohm and things like poor probe contact will have a disproportionate effect on the readings.

[HxPaul]

Thanks for the answers.The reason I ask is,I have a spare Indian stator plate and the last time I used it the lights seemed to flicker on and off every now and then,the ignition coil and pick up work ok.

[Nelly]

Had a check.
The Vespa Haynes manual says there are no resistance figures available due to the low resistance. It does say that there should be a small resistance but any flat resistance reading (0 ohms) could be showing a short circuit in the coils. It says to try changing the stator plate if it is suspected as faulty, which is what most people would do anyhow.
The reading you get from your multimeter will all depend on the accuracy of the instrument and what scale it is set to.
I always like to short the probes (zero the meter) before doing any low resistance testing just to ensure you are taking the resistance of the meter leads into account.
My Fluke multimeter has a function to zero the meter by shorting the leads and pressing the zero function button. I then know that any resistance shown is on the job I'm testing. This is particularly important when testing things such as variable thermistors, such as the ones used in cylinder head temperature sensors, they show a particular resistance at certain temperatures.

[HxPaul]

I checked the resistance of the lighting coils as you said and I got a reading of 1ohm and after about 5 seconds it dropped to zero,I did this three times and got the same reading each time.I'm starting to think that the flickering on and off could have been a loose connection.