Stator Failure

[jonno]

Why do stators keep failing Ive had 2 go this year after not many miles the latest while checking jetting which makes it impossible. Ive had an SR tested one and a BGM fail. Any long term reliable ones available or is it varitronic type time?

[Knowledge]

Anthony Tambs Scootronics stator. Built with top components and tested before dispatch.

Find him on Facebook.

[Fast n Furious]

Presumably........ when you say failing ..... you are referring to the LT coil?
The LT coil on a CDI stator is wound on a former with very fine copper wire. I can't remember the gauge of it but it has very little mechanical strength.
On production units, one end of the coil's connection is terminated to a ferrule on the plastic bobbin where the green ignition wire is also soldered.
The other end (earth), is welded to a tag on the stators laminate core. This connection is mechanically tight. The very fine wire is subject to the vibration stresses that Lambrettas are renowned for. As a result, the wire fractures. Naturally, it fractures where you can't inspect it.
When the engine is cold, they will usually run ok as this fractured wire maintains its electrical connection. As things expand and move with heat and vibration, you then experience these difficult to fathom running problems. Sometimes, they can just fail terminally, which makes it easier to diagnose.
You can check for LT coil breakdown by using a muliti-meter set on the circa 200Vac range. (An analogue meter works better here than a digital one. About £4 on fleabay)
Remove the headset top and connect one probe lead to the green ignition wire and the other to chassis.
Start the engine and it should read between 60Vac - 200ish Vac as you rev it out.
Tape the meter to the headset and go for a ride.
If the meter reading unexpectedly drops when your engine begins to splutter then you can blame the LT coil.
If the coil is goosed altogether, then you can expect to see little or no voltage when kick starting with the plug out.
They can be successfully repaired by installing a new LT coil.
I make an extra hole in the plastic base of the coil bobbin and insert a small solderable ferrule eye. The coil's earth wire is now soldered to the ferrule along with a separate earth wire which joins the coil termination point to the laminate earthing point. This secondary multi-stranded earthing wire now takes the brunt of the vibration and not the coil itself.

It's now getting common to use the Lukas style CDI, which gets its power from the lighting coils making the LT coil redundant, which is a good conversion if you can't be arsed to pull the stator apart.

[Knowledge]

... or buy a decent stator off Anthony Tambs

[Scooterdude]

Don’t get hung up with the boutique BGM stators, they’re shit, had one go on me a couple of years back. After a couple of other fails im bobbing along on an Indian no name stator i repaired myself, so far it’s been fine.

[holty]

the Anthony tambs components are very good, f@f is right about the thin wire on the low tension coil and Anthony has had his low tension coils made to his own spec to help with this issue, he can sell you a stator that is very good, your other option is to use a tambs external pickup, which im using and a dc/ac external cdi and coil, im not using the internal part, except the lighting coils which don't fail very often, in fact my stator bolts came loose and it still ran fine. lots have both internal and external systems fitted so you have 2 stand alone systems which will give you the ability to switch between the 2 in the event of a failure, you will find Anthony under scootronics on facebook, he is a rally going scooterist and very helpful I will be ordering some more parts from him soon.

holty

[dscscotty]

Casatronic or Varitronic resolved all my ignition woes on many motors including a group 6 RB260, 1000's miles and races without any ignition faults

[MickYork]

I use a DC powered cdi, running off a wet battery. Coupled with an external pick up this is has proved reliable over the last few thousand miles.......saying that my BGM stator never let me down and is still fitted as back up.

[kennystag]

Yes Anthony Tambs is your man for all things lammy electrics, top man and very helpful.

Stag

[jonno]

Got new stator from Mr Tambs.What do I need to check in order to use or not use the extra shims for the pickup?

[HxPaul]

Got new stator from Mr Tambs.What do I need to check in order to use or not use the extra shims for the pickup?

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