You're right! If the coil is connected directly to the plug rather than through the distributor cap, it should be fine.
Misc: Ignition Coil Ignition
- Thread starter Peter Holmes
- Start date
No, you don´t burn contacts just by having them closed for long time but you can wreck the coil by overheating. There just is no spark there in this condition for wearing the contacts and anyway only about 3-4 amps. You get more wear on contacts with battery ignition as positive is positive on the same contact all the time. With a twin magneto polarity changes so wear on contacts will be even for both sides. Yes, a twin coil and two lobes in the ignition is a good setup, no distributor needed, like with all BMW twins, magneto or battery ignition. Wasted spark no deal, same with singles with contact breaker on crankshaft end like single BMWs , Horex and all.
You cannot have a twin coil with only one spark plug operating and leave one ht lead unconnected, it will develop an internal short in time. In that case grind away one lobe for a single system.
Vic
You cannot have a twin coil with only one spark plug operating and leave one ht lead unconnected, it will develop an internal short in time. In that case grind away one lobe for a single system.
Vic
I am looking to put a spare ignition coil on the shelf as a spare, so it is there should I need it in a hurry anytime, I am looking at a Lucas 47276 12 volt as fitted to later British bikes, Triumph etc. 1968 onwards,
looking at the info it states that has a 4.8 ohm primary coil resistance and then an 8.9 k/ohm secondary coil resistance, all gobbledegook to me, what does it mean, is that a greedy coil, will my Lucas 12v converted dynamo keep up with demand, are there any other 12 volt coils that will do as good a job but consume less.
looking at the info it states that has a 4.8 ohm primary coil resistance and then an 8.9 k/ohm secondary coil resistance, all gobbledegook to me, what does it mean, is that a greedy coil, will my Lucas 12v converted dynamo keep up with demand, are there any other 12 volt coils that will do as good a job but consume less.
Basically you hook the ignition coil onto a battery and test the current/amps the coil draws. When you get a 6 V battery first you will not do any harm to any coil. A contact breaker will not like to do more than 4 amps for a long time so when you see around 3-4 amps the coil is a 6 V type. Same coil connected to a 12 battery will draw twice the current, that is 6-8 amps - not acceptable. A 12 V coil will have a higher resistance so on 12 v you will see 3-4 amps again, allright for 12 systems.
Coils for electronics got maybe half of resistance and draw twice the current again, so not suitable for battery ignition with contact breaker plus capacitor. So get a coil with max. 4 amps current in your syystem. I don´t see how you can save much of electric power in the ignition set, you´d get a poor spark. To be open, I would not want cdi electronics as the sparks look extremely poor compared to strong magnetos with their loud fat sparks - no , not the typical Lucas rotating coil devices, hopeless.
Vic
Coils for electronics got maybe half of resistance and draw twice the current again, so not suitable for battery ignition with contact breaker plus capacitor. So get a coil with max. 4 amps current in your syystem. I don´t see how you can save much of electric power in the ignition set, you´d get a poor spark. To be open, I would not want cdi electronics as the sparks look extremely poor compared to strong magnetos with their loud fat sparks - no , not the typical Lucas rotating coil devices, hopeless.
Vic
I think that will be fine, I always carry one in my tank bag !,
My 12v one got me out of trouble when one of my Rita 6v coils packed up on the ex L/ning,
It was a faulty coil, Almost new !.
You can do about a 100 miles on a 6v setup , "D" Distributor, With no charge !!,
From a fully charged battery.
If you have charging fault , Best to disconnect the charging system ?,
I lent a bloke my battery at Cadwell Park, So he could get back to London,
Told him to disconnect, But He didn't, Weeks later he gave me my battery back,
But it was Buggered !.
My 12v one got me out of trouble when one of my Rita 6v coils packed up on the ex L/ning,
It was a faulty coil, Almost new !.
You can do about a 100 miles on a 6v setup , "D" Distributor, With no charge !!,
From a fully charged battery.
If you have charging fault , Best to disconnect the charging system ?,
I lent a bloke my battery at Cadwell Park, So he could get back to London,
Told him to disconnect, But He didn't, Weeks later he gave me my battery back,
But it was Buggered !.
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Peter, Ohm's Law is your friend in this but to save you looking it up I calculate that the coil you mention will allow 2.5 amps to pass at 12 volts. That is 30 Watts. However, it is only taking this when the points are closed so, depending upon how long the points are open in any one ignition cycle, you might only use 75 - 80% of that. You would have to look at the cam profile in the distributor to get a better value. It depends upon how your dynamo was converted to 12 volts as to how much it will put out but supposing that it is still no more than 60 Watts, i.e. five amps then somewhere well under half the potential output will be taken by the coil. It will depend upon whether you ride all the time with the headlight on and what power of bulb you use as to whether you will be happy with it. If the dynamo conversion still gives out the original 10 amps then there should be no problem.
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OK lots of clever people on this forum, which is great, thats why I love it. So the replacement coil that I have fitted is a genuine Lucas 12 volt coil, but made in India, fingers crossed that it is made to the same standards as when they were made in England. So as a curious type of person, what other 12 volt coils are out there, I see oil filled are available, is there a benefit? also are there more efficient coils, ie put less in and get more out, or does that defy the laws of physics, or Ohm's law or something. I don't really need to know any of this stuff, but I just find it extremely interesting to know, whats that saying "knowledge is power"
Re: Vic's comments, which I will add that I am extremely grateful for, but when Vic denigrates the humble Lucas KVF magneto, I have done countless miles using those devices, true I have had one catastrophic breakdown whilst using one, most frustrating, but thankfully fairly close to home, and at an age when I was far more resilient to adversity that I would be now. Then I moved to modern day BT-H CDI unit or whatever it is, which has worked for me really well (this is on a twin, not the Comet) but the coils did fail on the Isle of Man in 2007 I think, but good old Bernie Draper bailed me out then, and I was able to resume the rally.
Re: Vic's comments, which I will add that I am extremely grateful for, but when Vic denigrates the humble Lucas KVF magneto, I have done countless miles using those devices, true I have had one catastrophic breakdown whilst using one, most frustrating, but thankfully fairly close to home, and at an age when I was far more resilient to adversity that I would be now. Then I moved to modern day BT-H CDI unit or whatever it is, which has worked for me really well (this is on a twin, not the Comet) but the coils did fail on the Isle of Man in 2007 I think, but good old Bernie Draper bailed me out then, and I was able to resume the rally.
Still got an old BTH Mag' on my Old Comet, Many years !,
But I have a "D" distributer ready , If it goes wrong,
But will have to fit my Walkernator,
Because I have a dead loss battery setup.
I think the "D" setup is the cheapest and the best.
But I have a "D" distributer ready , If it goes wrong,
But will have to fit my Walkernator,
Because I have a dead loss battery setup.
I think the "D" setup is the cheapest and the best.
I've used both coil and magnetos for road bikes and for racing.......They are as good and bad as each other......It's only a matter of when any of them can fail.......But 9 times out of 10 its poor or nil maintenance that can result in failure........Most folk are hopeless with electrics anyway so that does not help........Some set ups are definitely better than others.......as far as magnetos, well the Scintilla is the best of the ones made to suit the Vincent, but these are hard to find and harder to find parts for, so that rules them out........electronic ignitions are not without their faults as well.......The main thing i don't like about most of them is the lack of adjust-ability in the advance curve.......So when someone asks me which is better, it is hard to give an answer because they all have good and bad points to them. From a simplicity point of view, a properly rebuilt magneto is hard to better.......Battery or no battery, it will still get you home.