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Discussion Starter · #1 ·
Didn't know what the hell was going on.Down to 1 turn out and still sooting up!The bike has always ran fine before now.Plugs are NGK B7ES's.
Then what did I notice?Coolant leaking from both coils,big time!Explains it all.When started from cold runs and ticks over fine,but as soon as i get moving and get the bike to do something that's it,coils get red hot.Bang,crack,splutter.......... dead.
The bike has just been completly re wired with Boyer ignition,the coils were new Lucas (yes I know :biglaugh:).
Does anyone know if something may have caused the coils to fail in this way,or have I just come across a faulty batch?:confused:
Any suggestions for replacement coils?
 

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'New' Lucas coils are actually a German (I think) coil (PZL ? ?) and not actually Lucas ... are they OLD Lucas coils? Been sitting for many years?

Anyway, I had a coil cook and start oozing once when the key got left on in my bike ... make sure your coils aren't staying 'hot' and are actually having their power supply switched off ...
 

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Discussion Starter · #3 ·
Just looked at the coils.They only have the Lucas MA12 sticker on them.As far as I can see,no reference to being made in Germany (that's not to say they aren't).Are you saying the German ones are something to try and avoid?
The power supply is definately being cut off on removal of the key.There's no question of dodgy wiring as the job was done for me by a reputable Brit Bike mechanic.
I'm not much of a mechanic (that's why I have the Thruxton too),I am right in thinking that the coils over heating are the root cause of my problem?
 

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Just looked at the coils.They only have the Lucas MA12 sticker on them.As far as I can see,no reference to being made in Germany (that's not to say they aren't).Are you saying the German ones are something to try and avoid?
The power supply is definately being cut off on removal of the key.There's no question of dodgy wiring as the job was done for me by a reputable Brit Bike mechanic.
I'm not much of a mechanic (that's why I have the Thruxton too),I am right in thinking that the coils over heating are the root cause of my problem?
Ton up,

I would say that the coils are the big problem you have over
there. The oil is the cooling medium for the coils, as it leaks out
the coil over heats. When it started to miss the wires actually
broke down in the coil. When they cool off it make a connection
again. That is why they work fine for a minute or two.

I could see one bad coil being had off a shelf, maybe two if you
are the unlucky type. But I would do a check to see what
the resistance of the coils primary winding is set at. I think the
Boyer system needed certain ohm reading.

Maybe someone with the system knows the answer and will chime
in on this matter.

Pookybear
 

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coil test

You can test one coil at at time on the bike. If one is a dud the other gets shorted. ref:Boyer trouble shooting guide.
 

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Discussion Starter · #6 ·
Thanks for your input guys.The ignition has gone to Boyer to be tested,this was a reccomendation by a few Brit parts dealerships (only £15 and it's replaced if it's faulty).I'll be getting new coils regardless.I'll keep you posted.
 
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