LT coil fecked - options?

[olliewtf]

although the options is obvious, ie replace the LT coil, someone has suggested that another fault on my stator could be the cause for its premature failure.

basically scoot was fine, then the next day it wouldnt start easily then wouldnt rev.
traced it back to the LT coil, it had a reading of 360 ohm. when i stripped the stator off, the coil was clearly burnt out, all the paper wrap was stained brown.

so I figured just replace the coil, but someone has suggested there is a chance that the cause could be outside of the coil, and i could run into the same issue again.
It is an indian stator from scooter restorations and has only done 300 ish miles. pickup was replaced after 5 miles as it self destructed, which SR did for me.

so.

just replace coil or replace whole stator?

how likely is it that, for example, the wrong grade wire is creating too much or too little resistance and causing the coil to burn out prematurely?

Im no electrician you see....

ta!

[Architecten]

It can also be bad earthing. I recently changed both the LT coil and Pick up, re-soldered everything, tightened up rivets to earth tabs, created another earth connection and araldited the lot. Works fine now...

[coaster]

It would I think be very unusual for the LT coil to 'burn out' under normal circumstances. The wire used is very fine and is insulated with a coating of lacquer. There are a few thousand turn on the bobbin and during manufacture dollops of coil winding lacquer are also applied to hold the conductors together. Unfortunately, slapdash application of the lacquer results in some layers being missed out and are then prone to vibration induced rubbing through of the wire insulation. This has the effect of lowering the resistance and will increase the operating temp maybe to the point of causing scorching. Nothing outside of the coil would cause it to burn out, even a full short as that is how the ignition is shut down (shorted directly to earth via the 2nd green in the cdi.

A new coil should sort it out but try and get hold of a good quality one.

[Monty]

1 small point check the ends of the laminates are clean and have not been rubbing the magnate . If it's rubbing it will get hot. I have in the past had to dremal .5mm off as it touched. I put tip ex on the laminate and it rubbed off on to the magnate.

[olliewtf]

cool, so its as i originally thought new coil should sort it. when i say the coil was burnt out, it wasn't, but the white tape had signs of burning. the coil itself still had resistance but just way too low to work.
also the top bent over laminate where it rested against the metal washer had loads of burnt shite on it from where i think the plastic housing of the coil had melted slightly. now this couldve of occured when the pickup shredded to many fine pieces and could be unrelated.

what is a good LT coil? SR sell SIL ones but thats the same as what packed in on mine and vespa ones require removal of some laminates do they not? I dont want to completely dissasemble the whole thing rivets and all as i may as just re rivet my spare. its more down to lack of proper tools, right now i can easily resolder a LT coil back on, but sorting out the rivets on the 'better' stator would cost more. but it does need doing. but i also want to repair this stator too.

would it also be a waste of time swapping the pickups over? on my other stator it reads 20/30 ohms higher than the indian k2 pickup.....

cheers all!

[olliewtf]

oh and Monty youre talking about the laminate faces rubbing on the flywheel magnets? will check that out that makes a lot of sense.

[Architecten]

A 'heat sink' supposedly helps keep the LT Coil cool...

[Solerunner1]

You didn't by any chance ride in the rain or hit puddles the day before did you? I have a friend who had wiring grommet/gasket troubles and he would burn out LT coils any time it rained. 3 Rain storms=3 coils burnt. Would run fine for hundreds of miles in the dry though.

[olliewtf]

Regards to heat sink; the vespa conversion stator is set up like that but the Indian one isn't. There's a metal washer with a fibre one behind it which I think are meant to act like a heat sink but that looks better as it's actually fixed to the backing plate.
And yes, it stopped working the day after it chucked it down. If this is a possible cause, what is the solution?
I think i may try and resurrect the vespa stator as it reads higher and the heat sinks and e arths are better.
I will repair this one too as a spare.
Any other tips and tricks let me know, the more I understand these things the better!

Ta all