Dual points for R69S (or any twin with magneto ignition)

[wa1nca]

John
Good question

Each coil would fire 2 times (Compression-wasted spark
advance lobe #1 fires coil #1 on compression stroke and next on exhaust
advance lobe #2 fires coil #2 on exhaust stroke and next on compression stroke
So by changing the point gap(timing) on one set of points would advance/retard for that cylinder
to match the opposite sides timing

Yea I really don"t know if it would work
I have seen pic of slash/2 bikes in Europe with 2 external mounted coils and guess with only one set of points?

The disadvantage is you would have to mount 2 coils outside of the bike,modify the point plate with another set of points, a good charging generator to kept the battery charged,ignition on/off switch

Best is get a good advance unit (if possible)
Fix it like Dave/Kurt suggest
Install the Vape ignition/charging upgrade

I think 2-4 degrees of differential timing is ok?

Tommy

[schrader7032]

Vech has said something like up to 3/16 inch was acceptable. Some of the differentail timing is due to the sloppy fit of the taper fit bolt on the front of the engine. Richard Coyle gave me instructions on how to tap on the mounting bolt in the right direction to reduce the difference. Worked a treat!

[wa1nca]

Kurt
3/16 Inch from Vech that good news
Richard Coyle gave me instructions on how to tap on the mounting bolt in the right direction to reduce the difference. Worked a treat!

Can you forward those

Thanks

[vechorik1373]

How to get rid of differential timing:

You can do this using an Ohm meter, if you do not have a magneto electronic timing tool.
1. Temporarily disconnect the wire from the coil to the points.
2. attach one lead of the ohm meter to the little nut and bolt of the points, using an alligator clip. Attach the other lead anywhere on the engine case for a ground.
3. remove both spark plugs so the engine will turn easy.
4. get yourself a regular lead pencil, and put the ohm meter right next to the flywheel viewing hole, so you can watch the meter and the flywheel at the same time.
5. put an allen wrench in the socket head cap screw that holds the generator on the crankshaft so you can turn the engine s-l-o-w-l-y.

Now, the coil (and the spark plugs) fire the instant that the points crack open. It is supposed to crack the points open and the line above the letter "S". So for this test, turn the engine slowly, and the instant the ohm meter shows the points crack open, (which should be the line above the letter S, but for this test, when the points open, indicated by the meter, put a pencil mark on the flywheel, next to the stationary "notch" cut into the viewing hole. Then turn the engine one complete revolution, and when the meter indicates the points cracked open, put a second pencil mark.
Now, the linear distance between the first pencil mark and the second mark, shows you how bad the differential timing is.
BMW allowed 3 degrees differential timing. Linearly, on the flywheel, that's about 3/16 of an inch. To have NO differential timing, you must have NO difference, no space between the pencil marks. If you do have a difference, turn the engine until the most advanced pencil mark is in the window, at the stationary mark in the viewing hole, confirmed by the meter.
Take a flat punch, and place it on the side of the bolt head that holds the advance on and get a light hammer. The idea here, is to drive the head of the bolt AWAY from the points. And we are not driving nails, here. Try one light light tap on the side of the bolt. Turn the engine backwards just a little, and then bring it forward and see if the meter indicates any change in the position that the points open in relation to the flywheel pencil mark.
What will/should happen, is the most advanced pencil mark will have moved toward the retard and the retarded mark will be moving toward the advance. In other words the actual two spots that the meter reacts will have moved closer together.
For absolute perfection, maybe tapping a bit more with the hammer, until you get it the two pencil marks to merge into one, or very close, anyway, and then swivel the breaker plate the points are mounted on, (if it is now opening the points twice in a row to far advanced or too far retarded, until the points open at the line above the letter "S" twice in a row.

[vechorik1373]

And on the subject of dual points, in my opinion, there is NO need to do this, you would just be creating new problems and gain nothing.
You know the K.I.S.S. principle... Keep It Simple, Stupid!

There is absolutely nothing wrong with the magneto ignition, when you have a good coil, and most importantly, a GOOD advance with no wear and you understand how it works, and how to set it up properly and eliminate differential timing.

[schrader7032]

Differential timing...what Vech said!

[101-Scout]

Vech, thanks for the tap by tap approach to addressing my differential timing (DTs) concerns ( over 0.5mm).
I'll KISS goodbye to the dual point musings as a practical approach to fixing the DT issue.
Are new Automatic Advanced Mechanisms still available to purchase?

Thanks to all those other contributors to this interesting topic.
I have another question, that I'll now post, about R51/3 rear wheel alignment and tyre clearance to RHS mudguard area.

[FL54]

Thanks Vech for detailed explanation. Can this be done with a Pentacomm plate?

[schrader7032]

The Pentacomm setup only provides a convenient way of changing the gap/timing. Seems like any differential timing would still be there.

[wa1nca]

Kurt
One set of points/coil would be for left cylinder
The other set for Right cylinder
So changing the gap on one set of points would advance/retard the timing for that side to match the other side
As Vech says KISS