Single coil

wavelenght2

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Apr 13, 2024
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CNW single coil: fitting the CNW single coil on my 72 combat however sticking with the existing points system. will this work ?

secondly, does this make condensers, ballast resistor etc redundant? thirdly, what happens with the white and purple wire, so far I have joined it to the B/White and to B/Yellow. Thank you for your replies
 
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Well,..... I use a single 3 ohm dyna dual plug coil combined with a boyer microdigital electronic ignition... but anyway,... Points do require condensers and ballast resistors. As I recall, the electronic ignition allows you to remove those components and the coil has nothing to do with their requirement. I put a boyer in place of the points 40 years ago and never had an ignition problem or had to adjust anything, except when I upgraded from the analog boyer to the digital one... 40 years of no fuss...

Let me just say that, points require YOU to know something about how they work to use them..... so just get a used boyer off Ebay and call it good. There's nothing romantic about running points on a motorcycle. I even dropped a pertronix points replacement module in my '69 Ford. I haven't had to touch the ignition since...

Queue the "points fanatics" to chime in on how much less current they draw and how they once rode home with a dead battery at night with a flashlight taped to their handlebars...
 
wavelenght2 said:
CNW single coil: fitting the CNW single coil on my 72 combat however sticking with the existing points system. will this work ?
Click to expand...

Apparently it does.

wavelenght2 said:
secondly, does this make condensers, ballast resistor etc redundant?
Click to expand...

The ballast must be disconnected (as you want the system to run at 12V). I believe you can disconnect one condenser.

wavelenght2 said:
what happens with the white and purple wire, so far I have joined it to the B/White and to B/Yellow.
Click to expand...

No, don't do that, the white/purple should connect to one side of the coil, B/W and B/Y to the other.
 
marshg246 said:
Each set of points opens once every 720 degrees of crank rotation. When the points open, the coil fires. To use a single coil, you need to fire once every 360 degrees of crank rotation. One side of each set of points is connected to ground and one set is always closed then the other is open. You could use the Black/White and Black/Yellow as a virtual single set of points that open once per 360 degree of crank rotation.

I would throw away the ballast resistor and white/purple wire and connect the white/yellow from the kill button to the black/yellow of the points. If you don't want the kill button, then the Black/Yellow to any white wire.

In this case White/Yellow -> Black/Yellow (points) Black/White -> coil "-". "+" of the coil -> ground.

Personally, I wouldn't waste the money on a single coil with points. To me, the money would be better spent on an electronic ignition.
Click to expand...
Thanks for that, a wealth of excellent info, I will be sure to follow it.
 
marshg246 said:
Each set of points opens once every 720 degrees of crank rotation. When the points open, the coil fires. To use a single coil, you need to fire once every 360 degrees of crank rotation. One side of each set of points is connected to ground and one set is always closed then the other is open. You could use the Black/White and Black/Yellow as a virtual single set of points that open once per 360 degree of crank rotation.

I would throw away the ballast resistor and white/purple wire and connect the white/yellow from the kill button to the black/yellow of the points. If you don't want the kill button, then the Black/Yellow to any white wire.

In this case White/Yellow -> Black/Yellow (points) Black/White -> coil "-". "+" of the coil -> ground.

Personally, I wouldn't waste the money on a single coil with points. To me, the money would be better spent on an electronic ignition.
Click to expand...
I'm reading Grant Tillers rendering of Bill Turnbull 72 wiring diagram (2013) showing white /purple to ballast resistor >white
/blue >white/yellow > presume kill button?
 
If you follow Paul Henshaw on youtube he is currently going on about points v EI and how he doesn't like EI. To each his own but I wondered if his recent postings haven't (re)triggered the
argument. Pardon the poor pun.
 
marshg246 said:
Depends on where you look:
Master Switch -> White -> Kill Button -> White/Yellow -> Ballast Resistor -> White/Purple
Master Switch -> White -> Kill Button -> White/Yellow -> White/Blue -> Ballast Resistor -> White/Purple

In either case, throw away any White/Blue, White/Purple, and ballast resistor and connect the White/Yellow to the Black/Yellow. Or, to make it even simpler, connect any plain white wire to the Black/Yellow (eliminates the kill button).
Click to expand...
the point about the kill button has come up before: the original wiring relies on that button making contact when NOT pressed, so if it is a dodgy contact, can result in misfires when riding.
 
According to L.A.B. I'm wrong so follow his instructions in post #3.
 
Onder said:
If you follow Paul Henshaw on youtube he is currently going on about points v EI and how he doesn't like EI. To each his own but I wondered if his recent postings haven't (re)triggered the
argument. Pardon the poor pun.
Click to expand...
The misfiring A65 videos? I have been following those (even though I dont have an A65).
 
YING said:
IMHO,toss your points into your spare parts bin and go with an electronic replacement.Install once correctly and forget it.
Mike
Click to expand...
That's basically what I have done with nearly all the Brit bikes I have owned
But there are merits to both systems
 
YING said:
IMHO,toss your points into your spare parts bin and go with an electronic replacement.Install once correctly and forget it.
Mike
Click to expand...
I did this about 45 years ago, haven't touched it since, but with points I was always having to faff around with them. Can't see the point of staying with something so needy.
 
MichaelD said:
I did this about 45 years ago, haven't touched it since, but with points I was always having to faff around with them. Can't see the point of staying with something so needy.
Click to expand...
Lucas Rita?
 
My Boyer is not programmable, so if I ever want to develop the bike further I might replace it. It is very reliable. I would avoid using points on any bike. Even in a magneto, they can be a problem. If a Boyer drops dead, just buy another one. But do not fit the wrong lead to the battery, or the smoke might escape. My coil is off a CB750 Honda.
 
L.A.B. said:
Apparently it does.



The ballast must be disconnected (as you want the system to run at 12V). I believe you can disconnect one condenser.



No, don't do that, the white/purple should connect to one side of the coil, B/W and B/Y to the other.
Click to expand...
therefore the purple and white can still be connected to the blue and white wire that seems to connect to yellow and white in Bill Turnbulls Diagram - minus the ballast resistor?
 
wavelenght2 said:
therefore the purple and white can still be connected to the blue and white wire that seems to connect to yellow and white in Bill Turnbulls Diagram - minus the ballast resistor?
Click to expand...

Yes, or connect white/purple directly to white/yellow so bypassing the white/blue.
 
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