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Dual points for R69S (or any twin with magneto ignition)
Dual points for R69S (or any twin with magneto ignition)
Please see pic below.
I have seen this picture of a very tidy dual point layout and configuration. I am unaware of the author. Perhaps someone previously posted this on this forum?
Any help or contact with original designs much appreciated.
Also I welcome any feedback on dual points to rectify timing discrepancies between L & R cylinders.
Doug
R51/3
NSW
Australia
- schrader7032
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Re: Dual points for R69S (or any twin with magneto ignition)
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
Re: Dual points for R69S (or any twin with magneto ignition)
- schrader7032
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Re: Dual points for R69S (or any twin with magneto ignition)
Then there's the issue with the magneto and how it works. The magneto only provides maximum output at the "abrisz" point. I wonder how that timing works in this situation.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
Re: Dual points for R69S (or any twin with magneto ignition)
My understanding, is that with standard magneto ignition setup the single point open and spark fires to both plugs every revolution of camshaft. Please correct me if not the case.
The design benefit of this setup, is with two sets of points one designated for each cylinder, therefore timing of spark could be set precisely and independently for each cylinder.
I would like to contact this person who has made this with intention to communicate his/her experience.
Anybody used or know of such?
R51/3
NSW
Australia
Re: Dual points for R69S (or any twin with magneto ignition)
So, after further discussion:
with dual points, I would need modification to cater for extra set of points firing only at the correct phase of 4 stroke
Perhaps - single timing cam or ???
Any thoughts appreciated.
R51/3
NSW
Australia
Re: Dual points for R69S (or any twin with magneto ignition)
the 8-cylinder engines you refer to have a single set of points and a distributor, this set-up would be the other way around almost, two sets of points in series, on the primary winding of a single coil, if we were talking about a 180 degree twin, it might just work, but on a boxer or a 360 parallel twin, (Triumph, Norton, BSA, etc.) both sets of points would be opening almost, or actually, simultaneously, it would run, given that the coil would spark both plugs when the leading set of points open, but there would be no differential timing (which is the object), and therefore no point to it, the lagging set of points would do nothing, except wear out.
However, if two separate coils were used, it could be achieved.
Re: Dual points for R69S (or any twin with magneto ignition)
Dave
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Re: Dual points for R69S (or any twin with magneto ignition)
Yes 2 coils would be neededniall4473 wrote: ↑Thu Dec 21, 2023 4:08 amSchrader,
the 8-cylinder engines you refer to have a single set of points and a distributor, this set-up would be the other way around almost, two sets of points in series, on the primary winding of a single coil, if we were talking about a 180 degree twin, it might just work, but on a boxer or a 360 parallel twin, (Triumph, Norton, BSA, etc.) both sets of points would be opening almost, or actually, simultaneously, it would run, given that the coil would spark both plugs when the leading set of points open, but there would be no differential timing (which is the object), and therefore no point to it, the lagging set of points would do nothing, except wear out.
However, if two separate coils were used, it could be achieved.
When the 1st set of points open 1st coil would fire off of one lobe of the advance
Then when the 2nd set of points open 2nd coil would fire off the other lobe of the advance
Any differential timing could now be offset by changing the gap slightly on one set of points
54 R51/3, 55 R50/Velorex 560 sidecar, 64 R27, 68 R69US, 75 R75/6
Ashfield, Ma
USA
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Re: Dual points for R69S (or any twin with magneto ignition)
Inquiring minds want to know.