Temporary ignition system?

[unclerob]

I was just reading an old magazine picked up at a jumble and in the readers advice section I noticed this....
" If your magneto has a worn cam ring it should be rectified but you can find out whether or not its causing problems by rigging up a temporary total loss battery and coil system."
It was written by Roy Bacon and gives no other details but the tone suggests it was a common thing to do and seems to assume that the person asking the question would know how to do that...
I certainly haven't and was just wondering if anyone else had tried this?

 

[Greybeard]

" If your magneto has a worn cam ring it should be rectified but you can find out whether or not its causing problems by rigging up a temporary total loss battery and coil system."
It was written by Roy Bacon and gives no other details but the tone suggests it was a common thing to do and seems to assume that the person asking the question would know how to do that...

Yeh, back then riders knew a thing or three about their machines!

[Butch (cb)]

You’d imagine that you could just use the points for switching and wire around that as suggested. But if we’re talking a worn cam ring then the points timing would be compromised so you’d just be back where you started. Wouldn’t you?

[bsa-bill]

Yeh, back then riders knew a thing or three about their machines!

well yes a difference being they were regular transport for work not occasional leisure and the little difficulties we encounter would be common place and known to many together with cures

[Triton Thrasher]

You’d imagine that you could just use the points for switching and wire around that as suggested. But if we’re talking a worn cam ring then the points timing would be compromised so you’d just be back where you started. Wouldn’t you?

You're right. It doesn't make sense.

You don't need to put current through the points to know whether and when they open and shut.

What people including me did do was use the points in the mag in a jury rigged coil ignition, rather than get the magneto rewound.

[unclerob]

I've been thinking about this all day since I read it and my head is beginning to hurt! But I was thinking that he meant the cam ring was worn unevenly so if you somehow connected the points to a coil or pair of coils and timed it to one or other then it would no longer matter that they weren't 180 degrees apart? Or would it!
It certainly seemed to me that he was saying you could ride the bike that way and that it was a method of ruling out uneven cam wear as a cause of the problem....

[bsa-bill]

so if you somehow connected the points to a coil or pair of coils and timed it to one or other then it would no longer matter that they weren't 180 degrees apart? Or would it!

Would work if you fired both plugs together I think (redundant spark system)

[chaterlea25]

Hi,

Would work if you fired both plugs together I think (redundant spark system)

Yes, but the errant side would spark as well, if this was too advanced then both cylinders would be

If the HT side of the mag only is faulty, I have gotten bikes running by wiring a coil to the cutout wire 
the coil will spark  on the energy transfer principle 
A double ended 6vcoil worked on a Tri**^h  twin

John

[Triton Thrasher]

Hi,

Would work if you fired both plugs together I think (redundant spark system)

Yes, but the errant side would spark as well, if this was too advanced then both cylinders would be

No- with a double ended coil, when the points are opened by one cam ramp, both plugs spark but only one cylinder fires.  So the cylinders are still timed by their own respective bump on the cam ring. 

If the HT side of the mag only is faulty, I have gotten bikes running by wiring a coil to the cutout wire 
the coil will spark  on the energy transfer principle 
A double ended 6vcoil worked on a Tri**^h  twin

John

I found I had to insulate the points centre screw from the points plate and have a brass strip over it to contact the brush and conduct to the "stationary" point. That was with a brass points plate: might be different with the steel type.

[chaterlea25]

Hi TT,
ok you are correct on the way the timing would work

The system I described is self generating,
Insulating the centre screw from the internal wiring would be necessary when using a battery I think

John

[Triton Thrasher]

Yes your modification is different, now that I read it properly.

[Clive54bsa]

Or perhaps Roy Bacon, (I have most of his books), had, what I call, a brain fart.